vendor/clang/clang-trunk-r291476

33 files changed, 2035 insertions, 461 deletions

diff --git a/lib/AST/ExprConstant.cpp b/lib/AST/ExprConstant.cpp
index 6dcb705c44d3..fe77c7f6f3bf 100644
--- a/lib/AST/ExprConstant.cpp
+++ b/lib/AST/ExprConstant.cpp
@@ -4543,6 +4543,12 @@ public:
                              Call.getLValueBase().dyn_cast<const ValueDecl*>());
       if (!FD)
         return Error(Callee);
+      // Don't call function pointers which have been cast to some other type.
+      // Per DR (no number yet), the caller and callee can differ in noexcept.
+      if (!Info.Ctx.hasSameFunctionTypeIgnoringExceptionSpec(
+        CalleeType->getPointeeType(), FD->getType())) {
+        return Error(E);
+      }
 
       // Overloaded operator calls to member functions are represented as normal
       // calls with '*this' as the first argument.
@@ -4558,14 +4564,42 @@ public:
           return false;
         This = &ThisVal;
         Args = Args.slice(1);
+      } else if (MD && MD->isLambdaStaticInvoker()) {   
+        // Map the static invoker for the lambda back to the call operator.
+        // Conveniently, we don't have to slice out the 'this' argument (as is
+        // being done for the non-static case), since a static member function
+        // doesn't have an implicit argument passed in.
+        const CXXRecordDecl *ClosureClass = MD->getParent();
+        assert(
+            ClosureClass->captures_begin() == ClosureClass->captures_end() &&
+            "Number of captures must be zero for conversion to function-ptr");
+
+        const CXXMethodDecl *LambdaCallOp =
+            ClosureClass->getLambdaCallOperator();
+
+        // Set 'FD', the function that will be called below, to the call
+        // operator.  If the closure object represents a generic lambda, find
+        // the corresponding specialization of the call operator.
+
+        if (ClosureClass->isGenericLambda()) {
+          assert(MD->isFunctionTemplateSpecialization() &&
+                 "A generic lambda's static-invoker function must be a "
+                 "template specialization");
+          const TemplateArgumentList *TAL = MD->getTemplateSpecializationArgs();
+          FunctionTemplateDecl *CallOpTemplate =
+              LambdaCallOp->getDescribedFunctionTemplate();
+          void *InsertPos = nullptr;
+          FunctionDecl *CorrespondingCallOpSpecialization =
+              CallOpTemplate->findSpecialization(TAL->asArray(), InsertPos);
+          assert(CorrespondingCallOpSpecialization &&
+                 "We must always have a function call operator specialization "
+                 "that corresponds to our static invoker specialization");
+          FD = cast<CXXMethodDecl>(CorrespondingCallOpSpecialization);
+        } else
+          FD = LambdaCallOp;
       }
 
-      // Don't call function pointers which have been cast to some other type.
-      // Per DR (no number yet), the caller and callee can differ in noexcept.
-      if (!Info.Ctx.hasSameFunctionTypeIgnoringExceptionSpec(
-              CalleeType->getPointeeType(), FD->getType())) {
-        return Error(E);
-      }
+      
     } else
       return Error(E);
 
@@ -5834,6 +5868,7 @@ namespace {
     bool VisitCXXConstructExpr(const CXXConstructExpr *E) {
       return VisitCXXConstructExpr(E, E->getType());
     }
+    bool VisitLambdaExpr(const LambdaExpr *E);
     bool VisitCXXInheritedCtorInitExpr(const CXXInheritedCtorInitExpr *E);
     bool VisitCXXConstructExpr(const CXXConstructExpr *E, QualType T);
     bool VisitCXXStdInitializerListExpr(const CXXStdInitializerListExpr *E);
@@ -6168,6 +6203,21 @@ bool RecordExprEvaluator::VisitCXXStdInitializerListExpr(
   return true;
 }
 
+bool RecordExprEvaluator::VisitLambdaExpr(const LambdaExpr *E) {
+  const CXXRecordDecl *ClosureClass = E->getLambdaClass();
+  if (ClosureClass->isInvalidDecl()) return false;
+
+  if (Info.checkingPotentialConstantExpression()) return true;
+  if (E->capture_size()) {
+    Info.FFDiag(E, diag::note_unimplemented_constexpr_lambda_feature_ast)
+        << "can not evaluate lambda expressions with captures";
+    return false;
+  }
+  // FIXME: Implement captures.
+  Result = APValue(APValue::UninitStruct(), /*NumBases*/0, /*NumFields*/0);
+  return true;
+}
+
 static bool EvaluateRecord(const Expr *E, const LValue &This,
                            APValue &Result, EvalInfo &Info) {
   assert(E->isRValue() && E->getType()->isRecordType() &&
@@ -6217,6 +6267,9 @@ public:
   bool VisitCXXStdInitializerListExpr(const CXXStdInitializerListExpr *E) {
     return VisitConstructExpr(E);
   }
+  bool VisitLambdaExpr(const LambdaExpr *E) {
+    return VisitConstructExpr(E);
+  }
 };
 } // end anonymous namespace
 
@@ -10357,10 +10410,25 @@ bool Expr::isCXX11ConstantExpr(const ASTContext &Ctx, APValue *Result,
 
 bool Expr::EvaluateWithSubstitution(APValue &Value, ASTContext &Ctx,
                                     const FunctionDecl *Callee,
-                                    ArrayRef<const Expr*> Args) const {
+                                    ArrayRef<const Expr*> Args,
+                                    const Expr *This) const {
   Expr::EvalStatus Status;
   EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantExpressionUnevaluated);
 
+  LValue ThisVal;
+  const LValue *ThisPtr = nullptr;
+  if (This) {
+#ifndef NDEBUG
+    auto *MD = dyn_cast<CXXMethodDecl>(Callee);
+    assert(MD && "Don't provide `this` for non-methods.");
+    assert(!MD->isStatic() && "Don't provide `this` for static methods.");
+#endif
+    if (EvaluateObjectArgument(Info, This, ThisVal))
+      ThisPtr = &ThisVal;
+    if (Info.EvalStatus.HasSideEffects)
+      return false;
+  }
+
   ArgVector ArgValues(Args.size());
   for (ArrayRef<const Expr*>::iterator I = Args.begin(), E = Args.end();
        I != E; ++I) {
@@ -10373,7 +10441,7 @@ bool Expr::EvaluateWithSubstitution(APValue &Value, ASTContext &Ctx,
   }
 
   // Build fake call to Callee.
-  CallStackFrame Frame(Info, Callee->getLocation(), Callee, /*This*/nullptr,
+  CallStackFrame Frame(Info, Callee->getLocation(), Callee, ThisPtr,
                        ArgValues.data());
   return Evaluate(Value, Info, this) && !Info.EvalStatus.HasSideEffects;
 }
diff --git a/lib/AST/MicrosoftMangle.cpp b/lib/AST/MicrosoftMangle.cpp
index 911b8b471a05..76c368d7f04c 100644
--- a/lib/AST/MicrosoftMangle.cpp
+++ b/lib/AST/MicrosoftMangle.cpp
@@ -109,13 +109,13 @@ static const DeclContext *getEffectiveParentContext(const DeclContext *DC) {
 
 static const FunctionDecl *getStructor(const NamedDecl *ND) {
   if (const auto *FTD = dyn_cast<FunctionTemplateDecl>(ND))
-    return FTD->getTemplatedDecl();
+    return FTD->getTemplatedDecl()->getCanonicalDecl();
 
   const auto *FD = cast<FunctionDecl>(ND);
   if (const auto *FTD = FD->getPrimaryTemplate())
-    return FTD->getTemplatedDecl();
+    return FTD->getTemplatedDecl()->getCanonicalDecl();
 
-  return FD;
+  return FD->getCanonicalDecl();
 }
 
 /// MicrosoftMangleContextImpl - Overrides the default MangleContext for the
@@ -312,6 +312,10 @@ public:
   void mangleNestedName(const NamedDecl *ND);
 
 private:
+  bool isStructorDecl(const NamedDecl *ND) const {
+    return ND == Structor || getStructor(ND) == Structor;
+  }
+
   void mangleUnqualifiedName(const NamedDecl *ND) {
     mangleUnqualifiedName(ND, ND->getDeclName());
   }
@@ -898,7 +902,7 @@ void MicrosoftCXXNameMangler::mangleUnqualifiedName(const NamedDecl *ND,
       llvm_unreachable("Can't mangle Objective-C selector names here!");
 
     case DeclarationName::CXXConstructorName:
-      if (Structor == getStructor(ND)) {
+      if (isStructorDecl(ND)) {
         if (StructorType == Ctor_CopyingClosure) {
           Out << "?_O";
           return;
@@ -912,7 +916,7 @@ void MicrosoftCXXNameMangler::mangleUnqualifiedName(const NamedDecl *ND,
       return;
 
     case DeclarationName::CXXDestructorName:
-      if (ND == Structor)
+      if (isStructorDecl(ND))
         // If the named decl is the C++ destructor we're mangling,
         // use the type we were given.
         mangleCXXDtorType(static_cast<CXXDtorType>(StructorType));
@@ -1862,7 +1866,7 @@ void MicrosoftCXXNameMangler::mangleFunctionType(const FunctionType *T,
       IsStructor = true;
       IsCtorClosure = (StructorType == Ctor_CopyingClosure ||
                        StructorType == Ctor_DefaultClosure) &&
-                      getStructor(MD) == Structor;
+                      isStructorDecl(MD);
       if (IsCtorClosure)
         CC = getASTContext().getDefaultCallingConvention(
             /*IsVariadic=*/false, /*IsCXXMethod=*/true);
@@ -1883,7 +1887,7 @@ void MicrosoftCXXNameMangler::mangleFunctionType(const FunctionType *T,
   // <return-type> ::= <type>
   //               ::= @ # structors (they have no declared return type)
   if (IsStructor) {
-    if (isa<CXXDestructorDecl>(D) && D == Structor &&
+    if (isa<CXXDestructorDecl>(D) && isStructorDecl(D) &&
         StructorType == Dtor_Deleting) {
       // The scalar deleting destructor takes an extra int argument.
       // However, the FunctionType generated has 0 arguments.
diff --git a/lib/CodeGen/BackendUtil.cpp b/lib/CodeGen/BackendUtil.cpp
index ed09f3a45566..d2ce6ea48e41 100644
--- a/lib/CodeGen/BackendUtil.cpp
+++ b/lib/CodeGen/BackendUtil.cpp
@@ -312,7 +312,8 @@ void EmitAssemblyHelper::CreatePasses(legacy::PassManager &MPM,
   // At O0 and O1 we only run the always inliner which is more efficient. At
   // higher optimization levels we run the normal inliner.
   if (CodeGenOpts.OptimizationLevel <= 1) {
-    bool InsertLifetimeIntrinsics = CodeGenOpts.OptimizationLevel != 0;
+    bool InsertLifetimeIntrinsics = (CodeGenOpts.OptimizationLevel != 0 &&
+                                     !CodeGenOpts.DisableLifetimeMarkers);
     PMBuilder.Inliner = createAlwaysInlinerLegacyPass(InsertLifetimeIntrinsics);
   } else {
     PMBuilder.Inliner = createFunctionInliningPass(
@@ -519,11 +520,22 @@ void EmitAssemblyHelper::CreateTargetMachine(bool MustCreateTM) {
            .Case("dynamic-no-pic", llvm::Reloc::DynamicNoPIC);
   assert(RM.hasValue() && "invalid PIC model!");
 
-  CodeGenOpt::Level OptLevel = CodeGenOpt::Default;
+  CodeGenOpt::Level OptLevel;
   switch (CodeGenOpts.OptimizationLevel) {
-  default: break;
-  case 0: OptLevel = CodeGenOpt::None; break;
-  case 3: OptLevel = CodeGenOpt::Aggressive; break;
+  default:
+    llvm_unreachable("Invalid optimization level!");
+  case 0:
+    OptLevel = CodeGenOpt::None;
+    break;
+  case 1:
+    OptLevel = CodeGenOpt::Less;
+    break;
+  case 2:
+    OptLevel = CodeGenOpt::Default;
+    break; // O2/Os/Oz
+  case 3:
+    OptLevel = CodeGenOpt::Aggressive;
+    break;
   }
 
   llvm::TargetOptions Options;
@@ -849,21 +861,8 @@ void EmitAssemblyHelper::EmitAssemblyWithNewPassManager(
   }
 }
 
-static void runThinLTOBackend(const CodeGenOptions &CGOpts, Module *M,
+static void runThinLTOBackend(ModuleSummaryIndex *CombinedIndex, Module *M,
                               std::unique_ptr<raw_pwrite_stream> OS) {
-  // If we are performing a ThinLTO importing compile, load the function index
-  // into memory and pass it into thinBackend, which will run the function
-  // importer and invoke LTO passes.
-  Expected<std::unique_ptr<ModuleSummaryIndex>> IndexOrErr =
-      llvm::getModuleSummaryIndexForFile(CGOpts.ThinLTOIndexFile);
-  if (!IndexOrErr) {
-    logAllUnhandledErrors(IndexOrErr.takeError(), errs(),
-                          "Error loading index file '" +
-                              CGOpts.ThinLTOIndexFile + "': ");
-    return;
-  }
-  std::unique_ptr<ModuleSummaryIndex> CombinedIndex = std::move(*IndexOrErr);
-
   StringMap<std::map<GlobalValue::GUID, GlobalValueSummary *>>
       ModuleToDefinedGVSummaries;
   CombinedIndex->collectDefinedGVSummariesPerModule(ModuleToDefinedGVSummaries);
@@ -949,8 +948,26 @@ void clang::EmitBackendOutput(DiagnosticsEngine &Diags,
                               BackendAction Action,
                               std::unique_ptr<raw_pwrite_stream> OS) {
   if (!CGOpts.ThinLTOIndexFile.empty()) {
-    runThinLTOBackend(CGOpts, M, std::move(OS));
-    return;
+    // If we are performing a ThinLTO importing compile, load the function index
+    // into memory and pass it into runThinLTOBackend, which will run the
+    // function importer and invoke LTO passes.
+    Expected<std::unique_ptr<ModuleSummaryIndex>> IndexOrErr =
+        llvm::getModuleSummaryIndexForFile(CGOpts.ThinLTOIndexFile);
+    if (!IndexOrErr) {
+      logAllUnhandledErrors(IndexOrErr.takeError(), errs(),
+                            "Error loading index file '" +
+                            CGOpts.ThinLTOIndexFile + "': ");
+      return;
+    }
+    std::unique_ptr<ModuleSummaryIndex> CombinedIndex = std::move(*IndexOrErr);
+    // A null CombinedIndex means we should skip ThinLTO compilation
+    // (LLVM will optionally ignore empty index files, returning null instead
+    // of an error).
+    bool DoThinLTOBackend = CombinedIndex != nullptr;
+    if (DoThinLTOBackend) {
+      runThinLTOBackend(CombinedIndex.get(), M, std::move(OS));
+      return;
+    }
   }
 
   EmitAssemblyHelper AsmHelper(Diags, HeaderOpts, CGOpts, TOpts, LOpts, M);
diff --git a/lib/CodeGen/CGCleanup.h b/lib/CodeGen/CGCleanup.h
index 2166490ec1fd..105c5629d50c 100644
--- a/lib/CodeGen/CGCleanup.h
+++ b/lib/CodeGen/CGCleanup.h
@@ -616,6 +616,8 @@ struct EHPersonality {
   static const EHPersonality GNU_C_SJLJ;
   static const EHPersonality GNU_C_SEH;
   static const EHPersonality GNU_ObjC;
+  static const EHPersonality GNU_ObjC_SJLJ;
+  static const EHPersonality GNU_ObjC_SEH;
   static const EHPersonality GNUstep_ObjC;
   static const EHPersonality GNU_ObjCXX;
   static const EHPersonality NeXT_ObjC;
diff --git a/lib/CodeGen/CGException.cpp b/lib/CodeGen/CGException.cpp
index 7b7880e07a95..f908bf2b3b0a 100644
--- a/lib/CodeGen/CGException.cpp
+++ b/lib/CodeGen/CGException.cpp
@@ -97,6 +97,10 @@ EHPersonality::GNU_CPlusPlus_SEH = { "__gxx_personality_seh0", nullptr };
 const EHPersonality
 EHPersonality::GNU_ObjC = {"__gnu_objc_personality_v0", "objc_exception_throw"};
 const EHPersonality
+EHPersonality::GNU_ObjC_SJLJ = {"__gnu_objc_personality_sj0", "objc_exception_throw"};
+const EHPersonality
+EHPersonality::GNU_ObjC_SEH = {"__gnu_objc_personality_seh0", "objc_exception_throw"};
+const EHPersonality
 EHPersonality::GNU_ObjCXX = { "__gnustep_objcxx_personality_v0", nullptr };
 const EHPersonality
 EHPersonality::GNUstep_ObjC = { "__gnustep_objc_personality_v0", nullptr };
@@ -137,6 +141,10 @@ static const EHPersonality &getObjCPersonality(const llvm::Triple &T,
     // fallthrough
   case ObjCRuntime::GCC:
   case ObjCRuntime::ObjFW:
+    if (L.SjLjExceptions)
+      return EHPersonality::GNU_ObjC_SJLJ;
+    else if (useLibGCCSEHPersonality(T))
+      return EHPersonality::GNU_ObjC_SEH;
     return EHPersonality::GNU_ObjC;
   }
   llvm_unreachable("bad runtime kind");
diff --git a/lib/CodeGen/CodeGenFunction.cpp b/lib/CodeGen/CodeGenFunction.cpp
index 7cab13de923b..137c69420ddf 100644
--- a/lib/CodeGen/CodeGenFunction.cpp
+++ b/lib/CodeGen/CodeGenFunction.cpp
@@ -42,6 +42,9 @@ using namespace CodeGen;
 /// markers.
 static bool shouldEmitLifetimeMarkers(const CodeGenOptions &CGOpts,
                                       const LangOptions &LangOpts) {
+  if (CGOpts.DisableLifetimeMarkers)
+    return false;
+
   // Asan uses markers for use-after-scope checks.
   if (CGOpts.SanitizeAddressUseAfterScope)
     return true;
diff --git a/lib/Driver/ToolChains.cpp b/lib/Driver/ToolChains.cpp
index 789a2f0525be..547e660ae09b 100644
--- a/lib/Driver/ToolChains.cpp
+++ b/lib/Driver/ToolChains.cpp
@@ -3812,6 +3812,7 @@ ToolChain::CXXStdlibType NetBSD::GetDefaultCXXStdlibType() const {
   if (Major >= 7 || Major == 0) {
     switch (getArch()) {
     case llvm::Triple::aarch64:
+    case llvm::Triple::aarch64_be:
     case llvm::Triple::arm:
     case llvm::Triple::armeb:
     case llvm::Triple::thumb:
diff --git a/lib/Driver/Tools.cpp b/lib/Driver/Tools.cpp
index 8e02d45fcc4a..e267cdb2649f 100644
--- a/lib/Driver/Tools.cpp
+++ b/lib/Driver/Tools.cpp
@@ -9644,6 +9644,7 @@ void netbsd::Linker::ConstructJob(Compilation &C, const JobAction &JA,
   if (Major >= 7 || Major == 0) {
     switch (getToolChain().getArch()) {
     case llvm::Triple::aarch64:
+    case llvm::Triple::aarch64_be:
     case llvm::Triple::arm:
     case llvm::Triple::armeb:
     case llvm::Triple::thumb:
diff --git a/lib/Format/TokenAnnotator.cpp b/lib/Format/TokenAnnotator.cpp
index cf6373f45657..b5f7de280acd 100644
--- a/lib/Format/TokenAnnotator.cpp
+++ b/lib/Format/TokenAnnotator.cpp
@@ -1282,9 +1282,7 @@ private:
       return TT_UnaryOperator;
 
     const FormatToken *NextToken = Tok.getNextNonComment();
-    if (!NextToken ||
-        NextToken->isOneOf(tok::arrow, Keywords.kw_final, tok::equal,
-                           Keywords.kw_override) ||
+    if (!NextToken || NextToken->isOneOf(tok::arrow, tok::equal) ||
         (NextToken->is(tok::l_brace) && !NextToken->getNextNonComment()))
       return TT_PointerOrReference;
 
@@ -2088,9 +2086,9 @@ bool TokenAnnotator::spaceRequiredBetween(const AnnotatedLine &Line,
         !Line.IsMultiVariableDeclStmt)))
     return true;
   if (Left.is(TT_PointerOrReference))
-    return Right.Tok.isLiteral() ||
-           Right.isOneOf(TT_BlockComment, Keywords.kw_final,
-                         Keywords.kw_override) ||
+    return Right.Tok.isLiteral() || Right.is(TT_BlockComment) ||
+           (Right.isOneOf(Keywords.kw_override, Keywords.kw_final) &&
+            !Right.is(TT_StartOfName)) ||
            (Right.is(tok::l_brace) && Right.BlockKind == BK_Block) ||
            (!Right.isOneOf(TT_PointerOrReference, TT_ArraySubscriptLSquare,
                            tok::l_paren) &&
diff --git a/lib/Format/UnwrappedLineParser.cpp b/lib/Format/UnwrappedLineParser.cpp
index 370cf7afa330..8fc3b78aee01 100644
--- a/lib/Format/UnwrappedLineParser.cpp
+++ b/lib/Format/UnwrappedLineParser.cpp
@@ -737,7 +737,7 @@ void UnwrappedLineParser::readTokenWithJavaScriptASI() {
       return;
   }
   if (Next->is(tok::exclaim) && PreviousMustBeValue)
-    addUnwrappedLine();
+    return addUnwrappedLine();
   bool NextMustBeValue = mustBeJSIdentOrValue(Keywords, Next);
   bool NextEndsTemplateExpr =
       Next->is(TT_TemplateString) && Next->TokenText.startswith("}");
@@ -745,9 +745,10 @@ void UnwrappedLineParser::readTokenWithJavaScriptASI() {
       (PreviousMustBeValue ||
        Previous->isOneOf(tok::r_square, tok::r_paren, tok::plusplus,
                          tok::minusminus)))
-    addUnwrappedLine();
-  if (PreviousMustBeValue && isJSDeclOrStmt(Keywords, Next))
-    addUnwrappedLine();
+    return addUnwrappedLine();
+  if ((PreviousMustBeValue || Previous->is(tok::r_brace)) &&
+      isJSDeclOrStmt(Keywords, Next))
+    return addUnwrappedLine();
 }
 
 void UnwrappedLineParser::parseStructuralElement() {
@@ -1974,7 +1975,14 @@ void UnwrappedLineParser::parseJavaScriptEs6ImportExport() {
       !FormatTok->isStringLiteral())
     return;
 
-  while (!eof() && FormatTok->isNot(tok::semi)) {
+  while (!eof()) {
+    if (FormatTok->is(tok::semi))
+      return;
+    if (Line->Tokens.size() == 0) {
+      // Common issue: Automatic Semicolon Insertion wrapped the line, so the
+      // import statement should terminate.
+      return;
+    }
     if (FormatTok->is(tok::l_brace)) {
       FormatTok->BlockKind = BK_Block;
       parseBracedList();
diff --git a/lib/Frontend/CompilerInvocation.cpp b/lib/Frontend/CompilerInvocation.cpp
index 93bbcc42da1a..36f6b0a5111a 100644
--- a/lib/Frontend/CompilerInvocation.cpp
+++ b/lib/Frontend/CompilerInvocation.cpp
@@ -520,6 +520,7 @@ static bool ParseCodeGenArgs(CodeGenOptions &Opts, ArgList &Args, InputKind IK,
     Opts.EmitLLVMUseLists = A->getOption().getID() == OPT_emit_llvm_uselists;
 
   Opts.DisableLLVMPasses = Args.hasArg(OPT_disable_llvm_passes);
+  Opts.DisableLifetimeMarkers = Args.hasArg(OPT_disable_lifetimemarkers);
   Opts.DisableRedZone = Args.hasArg(OPT_disable_red_zone);
   Opts.ForbidGuardVariables = Args.hasArg(OPT_fforbid_guard_variables);
   Opts.UseRegisterSizedBitfieldAccess = Args.hasArg(
diff --git a/lib/Frontend/FrontendActions.cpp b/lib/Frontend/FrontendActions.cpp
index eb91940cbbfc..f795a1d0475a 100644
--- a/lib/Frontend/FrontendActions.cpp
+++ b/lib/Frontend/FrontendActions.cpp
@@ -127,6 +127,12 @@ GeneratePCHAction::ComputeASTConsumerArguments(CompilerInstance &CI,
   return OS;
 }
 
+bool GeneratePCHAction::BeginSourceFileAction(CompilerInstance &CI,
+                                              StringRef Filename) {
+  CI.getLangOpts().CompilingPCH = true;
+  return true;
+}
+
 std::unique_ptr<ASTConsumer>
 GenerateModuleAction::CreateASTConsumer(CompilerInstance &CI,
                                         StringRef InFile) {
diff --git a/lib/Index/IndexSymbol.cpp b/lib/Index/IndexSymbol.cpp
index b2342453a916..be847e762091 100644
--- a/lib/Index/IndexSymbol.cpp
+++ b/lib/Index/IndexSymbol.cpp
@@ -53,6 +53,7 @@ SymbolInfo index::getSymbolInfo(const Decl *D) {
   assert(D);
   SymbolInfo Info;
   Info.Kind = SymbolKind::Unknown;
+  Info.SubKind = SymbolSubKind::None;
   Info.Properties = SymbolPropertySet();
   Info.Lang = SymbolLanguage::C;
 
@@ -183,10 +184,16 @@ SymbolInfo index::getSymbolInfo(const Decl *D) {
       Info.Kind = SymbolKind::NamespaceAlias;
       Info.Lang = SymbolLanguage::CXX;
       break;
-    case Decl::CXXConstructor:
+    case Decl::CXXConstructor: {
       Info.Kind = SymbolKind::Constructor;
       Info.Lang = SymbolLanguage::CXX;
+      auto *CD = cast<CXXConstructorDecl>(D);
+      if (CD->isCopyConstructor())
+        Info.SubKind = SymbolSubKind::CXXCopyConstructor;
+      else if (CD->isMoveConstructor())
+        Info.SubKind = SymbolSubKind::CXXMoveConstructor;
       break;
+    }
     case Decl::CXXDestructor:
       Info.Kind = SymbolKind::Destructor;
       Info.Lang = SymbolLanguage::CXX;
@@ -363,6 +370,15 @@ StringRef index::getSymbolKindString(SymbolKind K) {
   llvm_unreachable("invalid symbol kind");
 }
 
+StringRef index::getSymbolSubKindString(SymbolSubKind K) {
+  switch (K) {
+  case SymbolSubKind::None: return "<none>";
+  case SymbolSubKind::CXXCopyConstructor: return "cxx-copy-ctor";
+  case SymbolSubKind::CXXMoveConstructor: return "cxx-move-ctor";
+  }
+  llvm_unreachable("invalid symbol subkind");
+}
+
 StringRef index::getSymbolLanguageString(SymbolLanguage K) {
   switch (K) {
   case SymbolLanguage::C: return "C";
diff --git a/lib/Lex/PPDirectives.cpp b/lib/Lex/PPDirectives.cpp
index 85504de3d15d..9661e7b13f72 100644
--- a/lib/Lex/PPDirectives.cpp
+++ b/lib/Lex/PPDirectives.cpp
@@ -1996,10 +1996,12 @@ void Preprocessor::HandleIncludeDirective(SourceLocation HashLoc,
 
   // Ask HeaderInfo if we should enter this #include file.  If not, #including
   // this file will have no effect.
+  bool SkipHeader = false;
   if (ShouldEnter &&
       !HeaderInfo.ShouldEnterIncludeFile(*this, File, isImport,
                                          SuggestedModule.getModule())) {
     ShouldEnter = false;
+    SkipHeader = true;
     if (Callbacks)
       Callbacks->FileSkipped(*File, FilenameTok, FileCharacter);
   }
@@ -2008,6 +2010,14 @@ void Preprocessor::HandleIncludeDirective(SourceLocation HashLoc,
   if (!ShouldEnter) {
     // If this is a module import, make it visible if needed.
     if (auto *M = SuggestedModule.getModule()) {
+      // When building a pch, -fmodule-name tells the compiler to textually
+      // include headers in the specified module. But it is possible that
+      // ShouldEnter is false because we are skipping the header. In that
+      // case, We are not importing the specified module.
+      if (SkipHeader && getLangOpts().CompilingPCH &&
+          M->getTopLevelModuleName() == getLangOpts().CurrentModule)
+        return;
+
       makeModuleVisible(M, HashLoc);
 
       if (IncludeTok.getIdentifierInfo()->getPPKeywordID() !=
@@ -2032,6 +2042,13 @@ void Preprocessor::HandleIncludeDirective(SourceLocation HashLoc,
 
   // Determine if we're switching to building a new submodule, and which one.
   if (auto *M = SuggestedModule.getModule()) {
+    // When building a pch, -fmodule-name tells the compiler to textually
+    // include headers in the specified module. We are not building the
+    // specified module.
+    if (getLangOpts().CompilingPCH &&
+        M->getTopLevelModuleName() == getLangOpts().CurrentModule)
+      return;
+
     assert(!CurSubmodule && "should not have marked this as a module yet");
     CurSubmodule = M;
 
diff --git a/lib/Parse/ParseDecl.cpp b/lib/Parse/ParseDecl.cpp
index ba24adefe6b0..833d93e4548a 100644
--- a/lib/Parse/ParseDecl.cpp
+++ b/lib/Parse/ParseDecl.cpp
@@ -306,10 +306,11 @@ unsigned Parser::ParseAttributeArgsCommon(
 
     // Parse the non-empty comma-separated list of expressions.
     do {
-      bool ShouldEnter = attributeParsedArgsUnevaluated(*AttrName);
+      bool Uneval = attributeParsedArgsUnevaluated(*AttrName);
       EnterExpressionEvaluationContext Unevaluated(
-          Actions, Sema::Unevaluated, /*LambdaContextDecl=*/nullptr,
-          /*IsDecltype=*/false, ShouldEnter);
+          Actions, Uneval ? Sema::Unevaluated : Sema::ConstantEvaluated,
+          /*LambdaContextDecl=*/nullptr,
+          /*IsDecltype=*/false);
 
       ExprResult ArgExpr(
           Actions.CorrectDelayedTyposInExpr(ParseAssignmentExpression()));
diff --git a/lib/Parse/ParseInit.cpp b/lib/Parse/ParseInit.cpp
index 4a68942f6d2c..fa6b75daed92 100644
--- a/lib/Parse/ParseInit.cpp
+++ b/lib/Parse/ParseInit.cpp
@@ -404,6 +404,10 @@ ExprResult Parser::ParseBraceInitializer() {
     return Actions.ActOnInitList(LBraceLoc, None, ConsumeBrace());
   }
 
+  // Enter an appropriate expression evaluation context for an initializer list.
+  EnterExpressionEvaluationContext EnterContext(
+      Actions, EnterExpressionEvaluationContext::InitList);
+
   bool InitExprsOk = true;
 
   while (1) {
diff --git a/lib/Sema/SemaChecking.cpp b/lib/Sema/SemaChecking.cpp
index 9c902959233f..49208e20a49d 100644
--- a/lib/Sema/SemaChecking.cpp
+++ b/lib/Sema/SemaChecking.cpp
@@ -1242,7 +1242,8 @@ bool Sema::CheckNeonBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
     QualType RHSTy = RHS.get()->getType();
 
     llvm::Triple::ArchType Arch = Context.getTargetInfo().getTriple().getArch();
-    bool IsPolyUnsigned = Arch == llvm::Triple::aarch64;
+    bool IsPolyUnsigned = Arch == llvm::Triple::aarch64 ||
+                          Arch == llvm::Triple::aarch64_be;
     bool IsInt64Long =
         Context.getTargetInfo().getInt64Type() == TargetInfo::SignedLong;
     QualType EltTy =
diff --git a/lib/Sema/SemaDeclAttr.cpp b/lib/Sema/SemaDeclAttr.cpp
index f9b6a91a300f..c6a5bc74145c 100644
--- a/lib/Sema/SemaDeclAttr.cpp
+++ b/lib/Sema/SemaDeclAttr.cpp
@@ -32,6 +32,7 @@
 #include "clang/Sema/Lookup.h"
 #include "clang/Sema/Scope.h"
 #include "clang/Sema/SemaInternal.h"
+#include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/Support/MathExtras.h"
 
@@ -890,34 +891,117 @@ static void handleLocksExcludedAttr(Sema &S, Decl *D,
                                Attr.getAttributeSpellingListIndex()));
 }
 
-static void handleEnableIfAttr(Sema &S, Decl *D, const AttributeList &Attr) {
-  S.Diag(Attr.getLoc(), diag::ext_clang_enable_if);
-
-  Expr *Cond = Attr.getArgAsExpr(0);
+static bool checkFunctionConditionAttr(Sema &S, Decl *D,
+                                       const AttributeList &Attr,
+                                       Expr *&Cond, StringRef &Msg) {
+  Cond = Attr.getArgAsExpr(0);
   if (!Cond->isTypeDependent()) {
     ExprResult Converted = S.PerformContextuallyConvertToBool(Cond);
     if (Converted.isInvalid())
-      return;
+      return false;
     Cond = Converted.get();
   }
 
-  StringRef Msg;
   if (!S.checkStringLiteralArgumentAttr(Attr, 1, Msg))
-    return;
+    return false;
+
+  if (Msg.empty())
+    Msg = "<no message provided>";
 
   SmallVector<PartialDiagnosticAt, 8> Diags;
   if (!Cond->isValueDependent() &&
       !Expr::isPotentialConstantExprUnevaluated(Cond, cast<FunctionDecl>(D),
                                                 Diags)) {
-    S.Diag(Attr.getLoc(), diag::err_enable_if_never_constant_expr);
+    S.Diag(Attr.getLoc(), diag::err_attr_cond_never_constant_expr)
+        << Attr.getName();
     for (const PartialDiagnosticAt &PDiag : Diags)
       S.Diag(PDiag.first, PDiag.second);
+    return false;
+  }
+  return true;
+}
+
+static void handleEnableIfAttr(Sema &S, Decl *D, const AttributeList &Attr) {
+  S.Diag(Attr.getLoc(), diag::ext_clang_enable_if);
+
+  Expr *Cond;
+  StringRef Msg;
+  if (checkFunctionConditionAttr(S, D, Attr, Cond, Msg))
+    D->addAttr(::new (S.Context)
+                   EnableIfAttr(Attr.getRange(), S.Context, Cond, Msg,
+                                Attr.getAttributeSpellingListIndex()));
+}
+
+namespace {
+/// Determines if a given Expr references any of the given function's
+/// ParmVarDecls, or the function's implicit `this` parameter (if applicable).
+class ArgumentDependenceChecker
+    : public RecursiveASTVisitor<ArgumentDependenceChecker> {
+#ifndef NDEBUG
+  const CXXRecordDecl *ClassType;
+#endif
+  llvm::SmallPtrSet<const ParmVarDecl *, 16> Parms;
+  bool Result;
+
+public:
+  ArgumentDependenceChecker(const FunctionDecl *FD) {
+#ifndef NDEBUG
+    if (const auto *MD = dyn_cast<CXXMethodDecl>(FD))
+      ClassType = MD->getParent();
+    else
+      ClassType = nullptr;
+#endif
+    Parms.insert(FD->param_begin(), FD->param_end());
+  }
+
+  bool referencesArgs(Expr *E) {
+    Result = false;
+    TraverseStmt(E);
+    return Result;
+  }
+
+  bool VisitCXXThisExpr(CXXThisExpr *E) {
+    assert(E->getType()->getPointeeCXXRecordDecl() == ClassType &&
+           "`this` doesn't refer to the enclosing class?");
+    Result = true;
+    return false;
+  }
+
+  bool VisitDeclRefExpr(DeclRefExpr *DRE) {
+    if (const auto *PVD = dyn_cast<ParmVarDecl>(DRE->getDecl()))
+      if (Parms.count(PVD)) {
+        Result = true;
+        return false;
+      }
+    return true;
+  }
+};
+}
+
+static void handleDiagnoseIfAttr(Sema &S, Decl *D, const AttributeList &Attr) {
+  S.Diag(Attr.getLoc(), diag::ext_clang_diagnose_if);
+
+  Expr *Cond;
+  StringRef Msg;
+  if (!checkFunctionConditionAttr(S, D, Attr, Cond, Msg))
+    return;
+
+  StringRef DiagTypeStr;
+  if (!S.checkStringLiteralArgumentAttr(Attr, 2, DiagTypeStr))
+    return;
+
+  DiagnoseIfAttr::DiagnosticType DiagType;
+  if (!DiagnoseIfAttr::ConvertStrToDiagnosticType(DiagTypeStr, DiagType)) {
+    S.Diag(Attr.getArgAsExpr(2)->getLocStart(),
+           diag::err_diagnose_if_invalid_diagnostic_type);
     return;
   }
 
-  D->addAttr(::new (S.Context)
-             EnableIfAttr(Attr.getRange(), S.Context, Cond, Msg,
-                          Attr.getAttributeSpellingListIndex()));
+  auto *FD = cast<FunctionDecl>(D);
+  bool ArgDependent = ArgumentDependenceChecker(FD).referencesArgs(Cond);
+  D->addAttr(::new (S.Context) DiagnoseIfAttr(
+      Attr.getRange(), S.Context, Cond, Msg, DiagType, ArgDependent, FD,
+      Attr.getAttributeSpellingListIndex()));
 }
 
 static void handlePassObjectSizeAttr(Sema &S, Decl *D,
@@ -5682,6 +5766,9 @@ static void ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D,
   case AttributeList::AT_EnableIf:
     handleEnableIfAttr(S, D, Attr);
     break;
+  case AttributeList::AT_DiagnoseIf:
+    handleDiagnoseIfAttr(S, D, Attr);
+    break;
   case AttributeList::AT_ExtVectorType:
     handleExtVectorTypeAttr(S, scope, D, Attr);
     break;
diff --git a/lib/Sema/SemaDeclCXX.cpp b/lib/Sema/SemaDeclCXX.cpp
index a650621b573a..a70e16cce18c 100644
--- a/lib/Sema/SemaDeclCXX.cpp
+++ b/lib/Sema/SemaDeclCXX.cpp
@@ -5395,14 +5395,32 @@ static void ReferenceDllExportedMethods(Sema &S, CXXRecordDecl *Class) {
   }
 }
 
-static void checkForMultipleExportedDefaultConstructors(Sema &S, CXXRecordDecl *Class) {
+static void checkForMultipleExportedDefaultConstructors(Sema &S,
+                                                        CXXRecordDecl *Class) {
+  // Only the MS ABI has default constructor closures, so we don't need to do
+  // this semantic checking anywhere else.
+  if (!S.Context.getTargetInfo().getCXXABI().isMicrosoft())
+    return;
+
   CXXConstructorDecl *LastExportedDefaultCtor = nullptr;
   for (Decl *Member : Class->decls()) {
     // Look for exported default constructors.
     auto *CD = dyn_cast<CXXConstructorDecl>(Member);
-    if (!CD || !CD->isDefaultConstructor() || !CD->hasAttr<DLLExportAttr>())
+    if (!CD || !CD->isDefaultConstructor())
+      continue;
+    auto *Attr = CD->getAttr<DLLExportAttr>();
+    if (!Attr)
       continue;
 
+    // If the class is non-dependent, mark the default arguments as ODR-used so
+    // that we can properly codegen the constructor closure.
+    if (!Class->isDependentContext()) {
+      for (ParmVarDecl *PD : CD->parameters()) {
+        (void)S.CheckCXXDefaultArgExpr(Attr->getLocation(), CD, PD);
+        S.DiscardCleanupsInEvaluationContext();
+      }
+    }
+
     if (LastExportedDefaultCtor) {
       S.Diag(LastExportedDefaultCtor->getLocation(),
              diag::err_attribute_dll_ambiguous_default_ctor)
@@ -9135,6 +9153,16 @@ NamedDecl *Sema::BuildUsingDeclaration(Scope *S, AccessSpecifier AS,
   // invalid).
   if (R.empty() &&
       NameInfo.getName().getNameKind() != DeclarationName::CXXConstructorName) {
+    // HACK: Work around a bug in libstdc++'s detection of ::gets. Sometimes
+    // it will believe that glibc provides a ::gets in cases where it does not,
+    // and will try to pull it into namespace std with a using-declaration.
+    // Just ignore the using-declaration in that case.
+    auto *II = NameInfo.getName().getAsIdentifierInfo();
+    if (getLangOpts().CPlusPlus14 && II && II->isStr("gets") &&
+        CurContext->isStdNamespace() &&
+        isa<TranslationUnitDecl>(LookupContext) &&
+        getSourceManager().isInSystemHeader(UsingLoc))
+      return nullptr;
     if (TypoCorrection Corrected = CorrectTypo(
             R.getLookupNameInfo(), R.getLookupKind(), S, &SS,
             llvm::make_unique<UsingValidatorCCC>(
@@ -9828,9 +9856,14 @@ Sema::ComputeDefaultedDefaultCtorExceptionSpec(SourceLocation Loc,
   }
 
   // Field constructors.
-  for (const auto *F : ClassDecl->fields()) {
+  for (auto *F : ClassDecl->fields()) {
     if (F->hasInClassInitializer()) {
-      if (Expr *E = F->getInClassInitializer())
+      Expr *E = F->getInClassInitializer();
+      if (!E)
+        // FIXME: It's a little wasteful to build and throw away a
+        // CXXDefaultInitExpr here.
+        E = BuildCXXDefaultInitExpr(Loc, F).get();
+      if (E)
         ExceptSpec.CalledExpr(E);
     } else if (const RecordType *RecordTy
               = Context.getBaseElementType(F->getType())->getAs<RecordType>()) {
@@ -12291,6 +12324,10 @@ ExprResult Sema::BuildCXXDefaultInitExpr(SourceLocation Loc, FieldDecl *Field) {
   if (Field->getInClassInitializer())
     return CXXDefaultInitExpr::Create(Context, Loc, Field);
 
+  // If we might have already tried and failed to instantiate, don't try again.
+  if (Field->isInvalidDecl())
+    return ExprError();
+
   // Maybe we haven't instantiated the in-class initializer. Go check the
   // pattern FieldDecl to see if it has one.
   CXXRecordDecl *ParentRD = cast<CXXRecordDecl>(Field->getParent());
@@ -12320,8 +12357,11 @@ ExprResult Sema::BuildCXXDefaultInitExpr(SourceLocation Loc, FieldDecl *Field) {
     }
 
     if (InstantiateInClassInitializer(Loc, Field, Pattern,
-                                      getTemplateInstantiationArgs(Field)))
+                                      getTemplateInstantiationArgs(Field))) {
+      // Don't diagnose this again.
+      Field->setInvalidDecl();
       return ExprError();
+    }
     return CXXDefaultInitExpr::Create(Context, Loc, Field);
   }
 
@@ -12344,6 +12384,8 @@ ExprResult Sema::BuildCXXDefaultInitExpr(SourceLocation Loc, FieldDecl *Field) {
       << OutermostClass << Field;
   Diag(Field->getLocEnd(), diag::note_in_class_initializer_not_yet_parsed);
 
+  // Don't diagnose this again.
+  Field->setInvalidDecl();
   return ExprError();
 }
 
diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index 1509b22a9e5a..d62e8fd68b64 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -342,6 +342,7 @@ bool Sema::DiagnoseUseOfDecl(NamedDecl *D, SourceLocation Loc,
   }
 
   // See if this is a deleted function.
+  SmallVector<DiagnoseIfAttr *, 4> DiagnoseIfWarnings;
   if (FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
     if (FD->isDeleted()) {
       auto *Ctor = dyn_cast<CXXConstructorDecl>(FD);
@@ -363,6 +364,12 @@ bool Sema::DiagnoseUseOfDecl(NamedDecl *D, SourceLocation Loc,
 
     if (getLangOpts().CUDA && !CheckCUDACall(Loc, FD))
       return true;
+
+    if (const DiagnoseIfAttr *A =
+            checkArgIndependentDiagnoseIf(FD, DiagnoseIfWarnings)) {
+      emitDiagnoseIfDiagnostic(Loc, A);
+      return true;
+    }
   }
 
   // [OpenMP 4.0], 2.15 declare reduction Directive, Restrictions
@@ -377,6 +384,10 @@ bool Sema::DiagnoseUseOfDecl(NamedDecl *D, SourceLocation Loc,
     Diag(D->getLocation(), diag::note_entity_declared_at) << D;
     return true;
   }
+
+  for (const auto *W : DiagnoseIfWarnings)
+    emitDiagnoseIfDiagnostic(Loc, W);
+
   DiagnoseAvailabilityOfDecl(*this, D, Loc, UnknownObjCClass,
                              ObjCPropertyAccess);
 
@@ -5154,12 +5165,40 @@ static FunctionDecl *rewriteBuiltinFunctionDecl(Sema *Sema, ASTContext &Context,
   return OverloadDecl;
 }
 
-static bool isNumberOfArgsValidForCall(Sema &S, const FunctionDecl *Callee,
-                                       std::size_t NumArgs) {
-  if (S.TooManyArguments(Callee->getNumParams(), NumArgs,
-                         /*PartialOverloading=*/false))
-    return Callee->isVariadic();
-  return Callee->getMinRequiredArguments() <= NumArgs;
+static void checkDirectCallValidity(Sema &S, const Expr *Fn,
+                                    FunctionDecl *Callee,
+                                    MultiExprArg ArgExprs) {
+  // `Callee` (when called with ArgExprs) may be ill-formed. enable_if (and
+  // similar attributes) really don't like it when functions are called with an
+  // invalid number of args.
+  if (S.TooManyArguments(Callee->getNumParams(), ArgExprs.size(),
+                         /*PartialOverloading=*/false) &&
+      !Callee->isVariadic())
+    return;
+  if (Callee->getMinRequiredArguments() > ArgExprs.size())
+    return;
+
+  if (const EnableIfAttr *Attr = S.CheckEnableIf(Callee, ArgExprs, true)) {
+    S.Diag(Fn->getLocStart(),
+           isa<CXXMethodDecl>(Callee)
+               ? diag::err_ovl_no_viable_member_function_in_call
+               : diag::err_ovl_no_viable_function_in_call)
+        << Callee << Callee->getSourceRange();
+    S.Diag(Callee->getLocation(),
+           diag::note_ovl_candidate_disabled_by_function_cond_attr)
+        << Attr->getCond()->getSourceRange() << Attr->getMessage();
+    return;
+  }
+
+  SmallVector<DiagnoseIfAttr *, 4> Nonfatal;
+  if (const DiagnoseIfAttr *Attr = S.checkArgDependentDiagnoseIf(
+          Callee, ArgExprs, Nonfatal, /*MissingImplicitThis=*/true)) {
+    S.emitDiagnoseIfDiagnostic(Fn->getLocStart(), Attr);
+    return;
+  }
+
+  for (const auto *W : Nonfatal)
+    S.emitDiagnoseIfDiagnostic(Fn->getLocStart(), W);
 }
 
 /// ActOnCallExpr - Handle a call to Fn with the specified array of arguments.
@@ -5294,26 +5333,8 @@ ExprResult Sema::ActOnCallExpr(Scope *Scope, Expr *Fn, SourceLocation LParenLoc,
 
     if (getLangOpts().OpenCL && checkOpenCLDisabledDecl(*FD, *Fn))
       return ExprError();
-    
-    // CheckEnableIf assumes that the we're passing in a sane number of args for
-    // FD, but that doesn't always hold true here. This is because, in some
-    // cases, we'll emit a diag about an ill-formed function call, but then
-    // we'll continue on as if the function call wasn't ill-formed. So, if the
-    // number of args looks incorrect, don't do enable_if checks; we should've
-    // already emitted an error about the bad call.
-    if (FD->hasAttr<EnableIfAttr>() &&
-        isNumberOfArgsValidForCall(*this, FD, ArgExprs.size())) {
-      if (const EnableIfAttr *Attr = CheckEnableIf(FD, ArgExprs, true)) {
-        Diag(Fn->getLocStart(),
-             isa<CXXMethodDecl>(FD)
-                 ? diag::err_ovl_no_viable_member_function_in_call
-                 : diag::err_ovl_no_viable_function_in_call)
-            << FD << FD->getSourceRange();
-        Diag(FD->getLocation(),
-             diag::note_ovl_candidate_disabled_by_enable_if_attr)
-            << Attr->getCond()->getSourceRange() << Attr->getMessage();
-      }
-    }
+
+    checkDirectCallValidity(*this, Fn, FD, ArgExprs);
   }
 
   return BuildResolvedCallExpr(Fn, NDecl, LParenLoc, ArgExprs, RParenLoc,
@@ -13097,8 +13118,16 @@ void Sema::PopExpressionEvaluationContext() {
         //   evaluate [...] a lambda-expression.
         D = diag::err_lambda_in_constant_expression;
       }
-      for (const auto *L : Rec.Lambdas)
-        Diag(L->getLocStart(), D);
+
+      // C++1z allows lambda expressions as core constant expressions.
+      // FIXME: In C++1z, reinstate the restrictions on lambda expressions (CWG
+      // 1607) from appearing within template-arguments and array-bounds that
+      // are part of function-signatures.  Be mindful that P0315 (Lambdas in
+      // unevaluated contexts) might lift some of these restrictions in a 
+      // future version.
+      if (Rec.Context != ConstantEvaluated || !getLangOpts().CPlusPlus1z)
+        for (const auto *L : Rec.Lambdas)
+          Diag(L->getLocStart(), D);
     } else {
       // Mark the capture expressions odr-used. This was deferred
       // during lambda expression creation.
@@ -13150,41 +13179,63 @@ ExprResult Sema::HandleExprEvaluationContextForTypeof(Expr *E) {
   return TransformToPotentiallyEvaluated(E);
 }
 
-static bool IsPotentiallyEvaluatedContext(Sema &SemaRef) {
-  // Do not mark anything as "used" within a dependent context; wait for
-  // an instantiation.
-  if (SemaRef.CurContext->isDependentContext())
-    return false;
-
+/// Are we within a context in which some evaluation could be performed (be it
+/// constant evaluation or runtime evaluation)? Sadly, this notion is not quite
+/// captured by C++'s idea of an "unevaluated context".
+static bool isEvaluatableContext(Sema &SemaRef) {
   switch (SemaRef.ExprEvalContexts.back().Context) {
     case Sema::Unevaluated:
     case Sema::UnevaluatedAbstract:
-      // We are in an expression that is not potentially evaluated; do nothing.
-      // (Depending on how you read the standard, we actually do need to do
-      // something here for null pointer constants, but the standard's
-      // definition of a null pointer constant is completely crazy.)
+    case Sema::DiscardedStatement:
+      // Expressions in this context are never evaluated.
+      return false;
+
+    case Sema::UnevaluatedList:
+    case Sema::ConstantEvaluated:
+    case Sema::PotentiallyEvaluated:
+      // Expressions in this context could be evaluated.
+      return true;
+
+    case Sema::PotentiallyEvaluatedIfUsed:
+      // Referenced declarations will only be used if the construct in the
+      // containing expression is used, at which point we'll be given another
+      // turn to mark them.
       return false;
+  }
+  llvm_unreachable("Invalid context");
+}
 
+/// Are we within a context in which references to resolved functions or to
+/// variables result in odr-use?
+static bool isOdrUseContext(Sema &SemaRef, bool SkipDependentUses = true) {
+  // An expression in a template is not really an expression until it's been
+  // instantiated, so it doesn't trigger odr-use.
+  if (SkipDependentUses && SemaRef.CurContext->isDependentContext())
+    return false;
+
+  switch (SemaRef.ExprEvalContexts.back().Context) {
+    case Sema::Unevaluated:
+    case Sema::UnevaluatedList:
+    case Sema::UnevaluatedAbstract:
     case Sema::DiscardedStatement:
-      // These are technically a potentially evaluated but they have the effect
-      // of suppressing use marking.
       return false;
 
     case Sema::ConstantEvaluated:
     case Sema::PotentiallyEvaluated:
-      // We are in a potentially evaluated expression (or a constant-expression
-      // in C++03); we need to do implicit template instantiation, implicitly
-      // define class members, and mark most declarations as used.
       return true;
 
     case Sema::PotentiallyEvaluatedIfUsed:
-      // Referenced declarations will only be used if the construct in the
-      // containing expression is used.
       return false;
   }
   llvm_unreachable("Invalid context");
 }
 
+static bool isImplicitlyDefinableConstexprFunction(FunctionDecl *Func) {
+  CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(Func);
+  return Func->isConstexpr() &&
+         (Func->isImplicitlyInstantiable() || (MD && !MD->isUserProvided()));
+}
+
 /// \brief Mark a function referenced, and check whether it is odr-used
 /// (C++ [basic.def.odr]p2, C99 6.9p3)
 void Sema::MarkFunctionReferenced(SourceLocation Loc, FunctionDecl *Func,
@@ -13200,7 +13251,7 @@ void Sema::MarkFunctionReferenced(SourceLocation Loc, FunctionDecl *Func,
   //
   // We (incorrectly) mark overload resolution as an unevaluated context, so we
   // can just check that here.
-  bool OdrUse = MightBeOdrUse && IsPotentiallyEvaluatedContext(*this);
+  bool OdrUse = MightBeOdrUse && isOdrUseContext(*this);
 
   // Determine whether we require a function definition to exist, per
   // C++11 [temp.inst]p3:
@@ -13209,27 +13260,11 @@ void Sema::MarkFunctionReferenced(SourceLocation Loc, FunctionDecl *Func,
   //   specialization is implicitly instantiated when the specialization is
   //   referenced in a context that requires a function definition to exist.
   //
-  // We consider constexpr function templates to be referenced in a context
-  // that requires a definition to exist whenever they are referenced.
-  //
-  // FIXME: This instantiates constexpr functions too frequently. If this is
-  // really an unevaluated context (and we're not just in the definition of a
-  // function template or overload resolution or other cases which we
-  // incorrectly consider to be unevaluated contexts), and we're not in a
-  // subexpression which we actually need to evaluate (for instance, a
-  // template argument, array bound or an expression in a braced-init-list),
-  // we are not permitted to instantiate this constexpr function definition.
-  //
-  // FIXME: This also implicitly defines special members too frequently. They
-  // are only supposed to be implicitly defined if they are odr-used, but they
-  // are not odr-used from constant expressions in unevaluated contexts.
-  // However, they cannot be referenced if they are deleted, and they are
-  // deleted whenever the implicit definition of the special member would
-  // fail (with very few exceptions).
-  CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(Func);
+  // That is either when this is an odr-use, or when a usage of a constexpr
+  // function occurs within an evaluatable context.
   bool NeedDefinition =
-      OdrUse || (Func->isConstexpr() && (Func->isImplicitlyInstantiable() ||
-                                         (MD && !MD->isUserProvided())));
+      OdrUse || (isEvaluatableContext(*this) &&
+                 isImplicitlyDefinableConstexprFunction(Func));
 
   // C++14 [temp.expl.spec]p6:
   //   If a template [...] is explicitly specialized then that specialization
@@ -14123,47 +14158,11 @@ static void DoMarkVarDeclReferenced(Sema &SemaRef, SourceLocation Loc,
   Var->setReferenced();
 
   TemplateSpecializationKind TSK = Var->getTemplateSpecializationKind();
-  bool MarkODRUsed = true;
-
-  // If the context is not potentially evaluated, this is not an odr-use and
-  // does not trigger instantiation.
-  if (!IsPotentiallyEvaluatedContext(SemaRef)) {
-    if (SemaRef.isUnevaluatedContext())
-      return;
-
-    // If we don't yet know whether this context is going to end up being an
-    // evaluated context, and we're referencing a variable from an enclosing
-    // scope, add a potential capture.
-    //
-    // FIXME: Is this necessary? These contexts are only used for default
-    // arguments, where local variables can't be used.
-    const bool RefersToEnclosingScope =
-        (SemaRef.CurContext != Var->getDeclContext() &&
-         Var->getDeclContext()->isFunctionOrMethod() && Var->hasLocalStorage());
-    if (RefersToEnclosingScope) {
-      if (LambdaScopeInfo *const LSI =
-              SemaRef.getCurLambda(/*IgnoreCapturedRegions=*/true)) {
-        // If a variable could potentially be odr-used, defer marking it so
-        // until we finish analyzing the full expression for any
-        // lvalue-to-rvalue
-        // or discarded value conversions that would obviate odr-use.
-        // Add it to the list of potential captures that will be analyzed
-        // later (ActOnFinishFullExpr) for eventual capture and odr-use marking
-        // unless the variable is a reference that was initialized by a constant
-        // expression (this will never need to be captured or odr-used).
-        assert(E && "Capture variable should be used in an expression.");
-        if (!Var->getType()->isReferenceType() ||
-            !IsVariableNonDependentAndAConstantExpression(Var, SemaRef.Context))
-          LSI->addPotentialCapture(E->IgnoreParens());
-      }
-    }
 
-    if (!isTemplateInstantiation(TSK))
-      return;
-
-    // Instantiate, but do not mark as odr-used, variable templates.
-    MarkODRUsed = false;
-  }
+  bool OdrUseContext = isOdrUseContext(SemaRef);
+  bool NeedDefinition =
+      OdrUseContext || (isEvaluatableContext(SemaRef) &&
+                        Var->isUsableInConstantExpressions(SemaRef.Context));
 
   VarTemplateSpecializationDecl *VarSpec =
       dyn_cast<VarTemplateSpecializationDecl>(Var);
@@ -14173,14 +14172,15 @@ static void DoMarkVarDeclReferenced(Sema &SemaRef, SourceLocation Loc,
   // If this might be a member specialization of a static data member, check
   // the specialization is visible. We already did the checks for variable
   // template specializations when we created them.
-  if (TSK != TSK_Undeclared && !isa<VarTemplateSpecializationDecl>(Var))
+  if (NeedDefinition && TSK != TSK_Undeclared &&
+      !isa<VarTemplateSpecializationDecl>(Var))
     SemaRef.checkSpecializationVisibility(Loc, Var);
 
   // Perform implicit instantiation of static data members, static data member
   // templates of class templates, and variable template specializations. Delay
   // instantiations of variable templates, except for those that could be used
   // in a constant expression.
-  if (isTemplateInstantiation(TSK)) {
+  if (NeedDefinition && isTemplateInstantiation(TSK)) {
     bool TryInstantiating = TSK == TSK_ImplicitInstantiation;
 
     if (TryInstantiating && !isa<VarTemplateSpecializationDecl>(Var)) {
@@ -14219,9 +14219,6 @@ static void DoMarkVarDeclReferenced(Sema &SemaRef, SourceLocation Loc,
     }
   }
 
-  if (!MarkODRUsed)
-    return;
-
   // Per C++11 [basic.def.odr], a variable is odr-used "unless it satisfies
   // the requirements for appearing in a constant expression (5.19) and, if
   // it is an object, the lvalue-to-rvalue conversion (4.1)
@@ -14230,14 +14227,41 @@ static void DoMarkVarDeclReferenced(Sema &SemaRef, SourceLocation Loc,
   // Note that we use the C++11 definition everywhere because nothing in
   // C++03 depends on whether we get the C++03 version correct. The second
   // part does not apply to references, since they are not objects.
-  if (E && IsVariableAConstantExpression(Var, SemaRef.Context)) {
+  if (OdrUseContext && E &&
+      IsVariableAConstantExpression(Var, SemaRef.Context)) {
     // A reference initialized by a constant expression can never be
     // odr-used, so simply ignore it.
     if (!Var->getType()->isReferenceType())
       SemaRef.MaybeODRUseExprs.insert(E);
-  } else
+  } else if (OdrUseContext) {
     MarkVarDeclODRUsed(Var, Loc, SemaRef,
                        /*MaxFunctionScopeIndex ptr*/ nullptr);
+  } else if (isOdrUseContext(SemaRef, /*SkipDependentUses*/false)) {
+    // If this is a dependent context, we don't need to mark variables as
+    // odr-used, but we may still need to track them for lambda capture.
+    // FIXME: Do we also need to do this inside dependent typeid expressions
+    // (which are modeled as unevaluated at this point)?
+    const bool RefersToEnclosingScope =
+        (SemaRef.CurContext != Var->getDeclContext() &&
+         Var->getDeclContext()->isFunctionOrMethod() && Var->hasLocalStorage());
+    if (RefersToEnclosingScope) {
+      if (LambdaScopeInfo *const LSI =
+              SemaRef.getCurLambda(/*IgnoreCapturedRegions=*/true)) {
+        // If a variable could potentially be odr-used, defer marking it so
+        // until we finish analyzing the full expression for any
+        // lvalue-to-rvalue
+        // or discarded value conversions that would obviate odr-use.
+        // Add it to the list of potential captures that will be analyzed
+        // later (ActOnFinishFullExpr) for eventual capture and odr-use marking
+        // unless the variable is a reference that was initialized by a constant
+        // expression (this will never need to be captured or odr-used).
+        assert(E && "Capture variable should be used in an expression.");
+        if (!Var->getType()->isReferenceType() ||
+            !IsVariableNonDependentAndAConstantExpression(Var, SemaRef.Context))
+          LSI->addPotentialCapture(E->IgnoreParens());
+      }
+    }
+  }
 }
 
 /// \brief Mark a variable referenced, and check whether it is odr-used
@@ -14333,9 +14357,13 @@ void Sema::MarkAnyDeclReferenced(SourceLocation Loc, Decl *D,
 }
 
 namespace {
-  // Mark all of the declarations referenced
+  // Mark all of the declarations used by a type as referenced.
   // FIXME: Not fully implemented yet! We need to have a better understanding
-  // of when we're entering
+  // of when we're entering a context we should not recurse into.
+  // FIXME: This is and EvaluatedExprMarker are more-or-less equivalent to
+  // TreeTransforms rebuilding the type in a new context. Rather than
+  // duplicating the TreeTransform logic, we should consider reusing it here.
+  // Currently that causes problems when rebuilding LambdaExprs.
   class MarkReferencedDecls : public RecursiveASTVisitor<MarkReferencedDecls> {
     Sema &S;
     SourceLocation Loc;
@@ -14346,33 +14374,28 @@ namespace {
     MarkReferencedDecls(Sema &S, SourceLocation Loc) : S(S), Loc(Loc) { }
 
     bool TraverseTemplateArgument(const TemplateArgument &Arg);
-    bool TraverseRecordType(RecordType *T);
   };
 }
 
 bool MarkReferencedDecls::TraverseTemplateArgument(
     const TemplateArgument &Arg) {
-  if (Arg.getKind() == TemplateArgument::Declaration) {
-    if (Decl *D = Arg.getAsDecl())
-      S.MarkAnyDeclReferenced(Loc, D, true);
+  {
+    // A non-type template argument is a constant-evaluated context.
+    EnterExpressionEvaluationContext Evaluated(S, Sema::ConstantEvaluated);
+    if (Arg.getKind() == TemplateArgument::Declaration) {
+      if (Decl *D = Arg.getAsDecl())
+        S.MarkAnyDeclReferenced(Loc, D, true);
+    } else if (Arg.getKind() == TemplateArgument::Expression) {
+      S.MarkDeclarationsReferencedInExpr(Arg.getAsExpr(), false);
+    }
   }
 
   return Inherited::TraverseTemplateArgument(Arg);
 }
 
-bool MarkReferencedDecls::TraverseRecordType(RecordType *T) {
-  if (ClassTemplateSpecializationDecl *Spec
-                  = dyn_cast<ClassTemplateSpecializationDecl>(T->getDecl())) {
-    const TemplateArgumentList &Args = Spec->getTemplateArgs();
-    return TraverseTemplateArguments(Args.data(), Args.size());
-  }
-
-  return true;
-}
-
 void Sema::MarkDeclarationsReferencedInType(SourceLocation Loc, QualType T) {
   MarkReferencedDecls Marker(*this, Loc);
-  Marker.TraverseType(Context.getCanonicalType(T));
+  Marker.TraverseType(T);
 }
 
 namespace {
@@ -14479,6 +14502,7 @@ bool Sema::DiagRuntimeBehavior(SourceLocation Loc, const Stmt *Statement,
                                const PartialDiagnostic &PD) {
   switch (ExprEvalContexts.back().Context) {
   case Unevaluated:
+  case UnevaluatedList:
   case UnevaluatedAbstract:
   case DiscardedStatement:
     // The argument will never be evaluated, so don't complain.
diff --git a/lib/Sema/SemaExprMember.cpp b/lib/Sema/SemaExprMember.cpp
index 806a3d813ee8..c9aa99ee383c 100644
--- a/lib/Sema/SemaExprMember.cpp
+++ b/lib/Sema/SemaExprMember.cpp
@@ -134,6 +134,7 @@ static IMAKind ClassifyImplicitMemberAccess(Sema &SemaRef,
   assert(!AbstractInstanceResult);
   switch (SemaRef.ExprEvalContexts.back().Context) {
   case Sema::Unevaluated:
+  case Sema::UnevaluatedList:
     if (isField && SemaRef.getLangOpts().CPlusPlus11)
       AbstractInstanceResult = IMA_Field_Uneval_Context;
     break;
diff --git a/lib/Sema/SemaInit.cpp b/lib/Sema/SemaInit.cpp
index befee05713e0..45eff5ee6b62 100644
--- a/lib/Sema/SemaInit.cpp
+++ b/lib/Sema/SemaInit.cpp
@@ -6561,6 +6561,13 @@ InitializationSequence::Perform(Sema &S,
     break;
   }
 
+  // Promote from an unevaluated context to an unevaluated list context in
+  // C++11 list-initialization; we need to instantiate entities usable in
+  // constant expressions here in order to perform narrowing checks =(
+  EnterExpressionEvaluationContext Evaluated(
+      S, EnterExpressionEvaluationContext::InitList,
+      CurInit.get() && isa<InitListExpr>(CurInit.get()));
+
   // C++ [class.abstract]p2:
   //   no objects of an abstract class can be created except as subobjects
   //   of a class derived from it
diff --git a/lib/Sema/SemaLambda.cpp b/lib/Sema/SemaLambda.cpp
index 3bae69164ffd..a0d574915eba 100644
--- a/lib/Sema/SemaLambda.cpp
+++ b/lib/Sema/SemaLambda.cpp
@@ -1274,7 +1274,7 @@ static void addFunctionPointerConversion(Sema &S,
                                 ConvTy, 
                                 ConvTSI,
                                 /*isInline=*/true, /*isExplicit=*/false,
-                                /*isConstexpr=*/false, 
+                                /*isConstexpr=*/S.getLangOpts().CPlusPlus1z, 
                                 CallOperator->getBody()->getLocEnd());
   Conversion->setAccess(AS_public);
   Conversion->setImplicit(true);
@@ -1565,6 +1565,7 @@ ExprResult Sema::BuildLambdaExpr(SourceLocation StartLoc, SourceLocation EndLoc,
     //   A lambda-expression shall not appear in an unevaluated operand
     //   (Clause 5).
     case Unevaluated:
+    case UnevaluatedList:
     case UnevaluatedAbstract:
     // C++1y [expr.const]p2:
     //   A conditional-expression e is a core constant expression unless the
diff --git a/lib/Sema/SemaLookup.cpp b/lib/Sema/SemaLookup.cpp
index 38a7b8c127cc..883e2ae264e9 100644
--- a/lib/Sema/SemaLookup.cpp
+++ b/lib/Sema/SemaLookup.cpp
@@ -2960,6 +2960,7 @@ Sema::SpecialMemberOverloadResult *Sema::LookupSpecialMember(CXXRecordDecl *RD,
     if (CXXMethodDecl *M = dyn_cast<CXXMethodDecl>(Cand->getUnderlyingDecl())) {
       if (SM == CXXCopyAssignment || SM == CXXMoveAssignment)
         AddMethodCandidate(M, Cand, RD, ThisTy, Classification,
+                           /*ThisArg=*/nullptr,
                            llvm::makeArrayRef(&Arg, NumArgs), OCS, true);
       else if (CtorInfo)
         AddOverloadCandidate(CtorInfo.Constructor, CtorInfo.FoundDecl,
@@ -2972,7 +2973,7 @@ Sema::SpecialMemberOverloadResult *Sema::LookupSpecialMember(CXXRecordDecl *RD,
       if (SM == CXXCopyAssignment || SM == CXXMoveAssignment)
         AddMethodTemplateCandidate(
             Tmpl, Cand, RD, nullptr, ThisTy, Classification,
-            llvm::makeArrayRef(&Arg, NumArgs), OCS, true);
+            /*ThisArg=*/nullptr, llvm::makeArrayRef(&Arg, NumArgs), OCS, true);
       else if (CtorInfo)
         AddTemplateOverloadCandidate(
             CtorInfo.ConstructorTmpl, CtorInfo.FoundDecl, nullptr,
diff --git a/lib/Sema/SemaOverload.cpp b/lib/Sema/SemaOverload.cpp
index 33574b9aec35..41f4fa746fc6 100644
--- a/lib/Sema/SemaOverload.cpp
+++ b/lib/Sema/SemaOverload.cpp
@@ -29,6 +29,7 @@
 #include "clang/Sema/Template.h"
 #include "clang/Sema/TemplateDeduction.h"
 #include "llvm/ADT/DenseSet.h"
+#include "llvm/ADT/Optional.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/SmallString.h"
@@ -589,7 +590,6 @@ clang::MakeDeductionFailureInfo(ASTContext &Context,
   Result.Result = static_cast<unsigned>(TDK);
   Result.HasDiagnostic = false;
   switch (TDK) {
-  case Sema::TDK_Success:
   case Sema::TDK_Invalid:
   case Sema::TDK_InstantiationDepth:
   case Sema::TDK_TooManyArguments:
@@ -645,6 +645,10 @@ clang::MakeDeductionFailureInfo(ASTContext &Context,
       Result.HasDiagnostic = true;
     }
     break;
+
+  case Sema::TDK_Success:
+  case Sema::TDK_NonDependentConversionFailure:
+    llvm_unreachable("not a deduction failure");
   }
 
   return Result;
@@ -660,6 +664,7 @@ void DeductionFailureInfo::Destroy() {
   case Sema::TDK_TooFewArguments:
   case Sema::TDK_InvalidExplicitArguments:
   case Sema::TDK_CUDATargetMismatch:
+  case Sema::TDK_NonDependentConversionFailure:
     break;
 
   case Sema::TDK_Inconsistent:
@@ -704,6 +709,7 @@ TemplateParameter DeductionFailureInfo::getTemplateParameter() {
   case Sema::TDK_DeducedMismatchNested:
   case Sema::TDK_NonDeducedMismatch:
   case Sema::TDK_CUDATargetMismatch:
+  case Sema::TDK_NonDependentConversionFailure:
     return TemplateParameter();
 
   case Sema::TDK_Incomplete:
@@ -735,6 +741,7 @@ TemplateArgumentList *DeductionFailureInfo::getTemplateArgumentList() {
   case Sema::TDK_Underqualified:
   case Sema::TDK_NonDeducedMismatch:
   case Sema::TDK_CUDATargetMismatch:
+  case Sema::TDK_NonDependentConversionFailure:
     return nullptr;
 
   case Sema::TDK_DeducedMismatch:
@@ -763,6 +770,7 @@ const TemplateArgument *DeductionFailureInfo::getFirstArg() {
   case Sema::TDK_InvalidExplicitArguments:
   case Sema::TDK_SubstitutionFailure:
   case Sema::TDK_CUDATargetMismatch:
+  case Sema::TDK_NonDependentConversionFailure:
     return nullptr;
 
   case Sema::TDK_Inconsistent:
@@ -791,6 +799,7 @@ const TemplateArgument *DeductionFailureInfo::getSecondArg() {
   case Sema::TDK_InvalidExplicitArguments:
   case Sema::TDK_SubstitutionFailure:
   case Sema::TDK_CUDATargetMismatch:
+  case Sema::TDK_NonDependentConversionFailure:
     return nullptr;
 
   case Sema::TDK_Inconsistent:
@@ -821,8 +830,8 @@ llvm::Optional<unsigned> DeductionFailureInfo::getCallArgIndex() {
 
 void OverloadCandidateSet::destroyCandidates() {
   for (iterator i = begin(), e = end(); i != e; ++i) {
-    for (unsigned ii = 0, ie = i->NumConversions; ii != ie; ++ii)
-      i->Conversions[ii].~ImplicitConversionSequence();
+    for (auto &C : i->Conversions)
+      C.~ImplicitConversionSequence();
     if (!i->Viable && i->FailureKind == ovl_fail_bad_deduction)
       i->DeductionFailure.Destroy();
   }
@@ -830,12 +839,20 @@ void OverloadCandidateSet::destroyCandidates() {
 
 void OverloadCandidateSet::clear() {
   destroyCandidates();
-  ConversionSequenceAllocator.Reset();
-  NumInlineSequences = 0;
+  // DiagnoseIfAttrs are just pointers, so we don't need to destroy them.
+  SlabAllocator.Reset();
+  NumInlineBytesUsed = 0;
   Candidates.clear();
   Functions.clear();
 }
 
+DiagnoseIfAttr **
+OverloadCandidateSet::addDiagnoseIfComplaints(ArrayRef<DiagnoseIfAttr *> CA) {
+  auto *DIA = slabAllocate<DiagnoseIfAttr *>(CA.size());
+  std::uninitialized_copy(CA.begin(), CA.end(), DIA);
+  return DIA;
+}
+
 namespace {
   class UnbridgedCastsSet {
     struct Entry {
@@ -5814,6 +5831,28 @@ static bool IsAcceptableNonMemberOperatorCandidate(ASTContext &Context,
   return false;
 }
 
+static void initDiagnoseIfComplaint(Sema &S, OverloadCandidateSet &CandidateSet,
+                                    OverloadCandidate &Candidate,
+                                    FunctionDecl *Function,
+                                    ArrayRef<Expr *> Args,
+                                    bool MissingImplicitThis = false,
+                                    Expr *ExplicitThis = nullptr) {
+  SmallVector<DiagnoseIfAttr *, 8> Results;
+  if (DiagnoseIfAttr *DIA = S.checkArgDependentDiagnoseIf(
+          Function, Args, Results, MissingImplicitThis, ExplicitThis)) {
+    Results.clear();
+    Results.push_back(DIA);
+  }
+
+  Candidate.NumTriggeredDiagnoseIfs = Results.size();
+  if (Results.empty())
+    Candidate.DiagnoseIfInfo = nullptr;
+  else if (Results.size() == 1)
+    Candidate.DiagnoseIfInfo = Results[0];
+  else
+    Candidate.DiagnoseIfInfo = CandidateSet.addDiagnoseIfComplaints(Results);
+}
+
 /// AddOverloadCandidate - Adds the given function to the set of
 /// candidate functions, using the given function call arguments.  If
 /// @p SuppressUserConversions, then don't allow user-defined
@@ -5829,7 +5868,8 @@ Sema::AddOverloadCandidate(FunctionDecl *Function,
                            OverloadCandidateSet &CandidateSet,
                            bool SuppressUserConversions,
                            bool PartialOverloading,
-                           bool AllowExplicit) {
+                           bool AllowExplicit,
+                           ConversionSequenceList EarlyConversions) {
   const FunctionProtoType *Proto
     = dyn_cast<FunctionProtoType>(Function->getType()->getAs<FunctionType>());
   assert(Proto && "Functions without a prototype cannot be overloaded");
@@ -5845,10 +5885,11 @@ Sema::AddOverloadCandidate(FunctionDecl *Function,
       // function, e.g., X::f(). We use an empty type for the implied
       // object argument (C++ [over.call.func]p3), and the acting context
       // is irrelevant.
-      AddMethodCandidate(Method, FoundDecl, Method->getParent(),
-                         QualType(), Expr::Classification::makeSimpleLValue(),
-                         Args, CandidateSet, SuppressUserConversions,
-                         PartialOverloading);
+      AddMethodCandidate(Method, FoundDecl, Method->getParent(), QualType(),
+                         Expr::Classification::makeSimpleLValue(),
+                         /*ThisArg=*/nullptr, Args, CandidateSet,
+                         SuppressUserConversions, PartialOverloading,
+                         EarlyConversions);
       return;
     }
     // We treat a constructor like a non-member function, since its object
@@ -5881,7 +5922,8 @@ Sema::AddOverloadCandidate(FunctionDecl *Function,
   EnterExpressionEvaluationContext Unevaluated(*this, Sema::Unevaluated);
 
   // Add this candidate
-  OverloadCandidate &Candidate = CandidateSet.addCandidate(Args.size());
+  OverloadCandidate &Candidate =
+      CandidateSet.addCandidate(Args.size(), EarlyConversions);
   Candidate.FoundDecl = FoundDecl;
   Candidate.Function = Function;
   Candidate.Viable = true;
@@ -5945,7 +5987,10 @@ Sema::AddOverloadCandidate(FunctionDecl *Function,
   // Determine the implicit conversion sequences for each of the
   // arguments.
   for (unsigned ArgIdx = 0; ArgIdx < Args.size(); ++ArgIdx) {
-    if (ArgIdx < NumParams) {
+    if (Candidate.Conversions[ArgIdx].isInitialized()) {
+      // We already formed a conversion sequence for this parameter during
+      // template argument deduction.
+    } else if (ArgIdx < NumParams) {
       // (C++ 13.3.2p3): for F to be a viable function, there shall
       // exist for each argument an implicit conversion sequence
       // (13.3.3.1) that converts that argument to the corresponding
@@ -5971,6 +6016,31 @@ Sema::AddOverloadCandidate(FunctionDecl *Function,
     }
   }
 
+  // C++ [over.best.ics]p4+: (proposed DR resolution)
+  //   If the target is the first parameter of an inherited constructor when
+  //   constructing an object of type C with an argument list that has exactly
+  //   one expression, an implicit conversion sequence cannot be formed if C is
+  //   reference-related to the type that the argument would have after the
+  //   application of the user-defined conversion (if any) and before the final
+  //   standard conversion sequence. 
+  auto *Shadow = dyn_cast<ConstructorUsingShadowDecl>(FoundDecl.getDecl());
+  if (Shadow && Args.size() == 1 && !isa<InitListExpr>(Args.front())) {
+    bool DerivedToBase, ObjCConversion, ObjCLifetimeConversion;
+    QualType ConvertedArgumentType = Args.front()->getType();
+    if (Candidate.Conversions[0].isUserDefined())
+      ConvertedArgumentType =
+          Candidate.Conversions[0].UserDefined.After.getFromType();
+    if (CompareReferenceRelationship(Args.front()->getLocStart(),
+                                     Context.getRecordType(Shadow->getParent()),
+                                     ConvertedArgumentType, DerivedToBase,
+                                     ObjCConversion,
+                                     ObjCLifetimeConversion) >= Ref_Related) {
+      Candidate.Viable = false;
+      Candidate.FailureKind = ovl_fail_inhctor_slice;
+      return;
+    }
+  }
+
   if (EnableIfAttr *FailedAttr = CheckEnableIf(Function, Args)) {
     Candidate.Viable = false;
     Candidate.FailureKind = ovl_fail_enable_if;
@@ -5983,6 +6053,8 @@ Sema::AddOverloadCandidate(FunctionDecl *Function,
     Candidate.FailureKind = ovl_fail_ext_disabled;
     return;
   }
+
+  initDiagnoseIfComplaint(*this, CandidateSet, Candidate, Function, Args);
 }
 
 ObjCMethodDecl *
@@ -6095,66 +6167,87 @@ getOrderedEnableIfAttrs(const FunctionDecl *Function) {
   return Result;
 }
 
-EnableIfAttr *Sema::CheckEnableIf(FunctionDecl *Function, ArrayRef<Expr *> Args,
-                                  bool MissingImplicitThis) {
-  auto EnableIfAttrs = getOrderedEnableIfAttrs(Function);
-  if (EnableIfAttrs.empty())
-    return nullptr;
-
-  SFINAETrap Trap(*this);
-  SmallVector<Expr *, 16> ConvertedArgs;
-  bool InitializationFailed = false;
+static bool
+convertArgsForAvailabilityChecks(Sema &S, FunctionDecl *Function, Expr *ThisArg,
+                                 ArrayRef<Expr *> Args, Sema::SFINAETrap &Trap,
+                                 bool MissingImplicitThis, Expr *&ConvertedThis,
+                                 SmallVectorImpl<Expr *> &ConvertedArgs) {
+  if (ThisArg) {
+    CXXMethodDecl *Method = cast<CXXMethodDecl>(Function);
+    assert(!isa<CXXConstructorDecl>(Method) &&
+           "Shouldn't have `this` for ctors!");
+    assert(!Method->isStatic() && "Shouldn't have `this` for static methods!");
+    ExprResult R = S.PerformObjectArgumentInitialization(
+        ThisArg, /*Qualifier=*/nullptr, Method, Method);
+    if (R.isInvalid())
+      return false;
+    ConvertedThis = R.get();
+  } else {
+    if (auto *MD = dyn_cast<CXXMethodDecl>(Function)) {
+      (void)MD;
+      assert((MissingImplicitThis || MD->isStatic() ||
+              isa<CXXConstructorDecl>(MD)) &&
+             "Expected `this` for non-ctor instance methods");
+    }
+    ConvertedThis = nullptr;
+  }
 
   // Ignore any variadic arguments. Converting them is pointless, since the
-  // user can't refer to them in the enable_if condition.
+  // user can't refer to them in the function condition.
   unsigned ArgSizeNoVarargs = std::min(Function->param_size(), Args.size());
 
   // Convert the arguments.
   for (unsigned I = 0; I != ArgSizeNoVarargs; ++I) {
     ExprResult R;
-    if (I == 0 && !MissingImplicitThis && isa<CXXMethodDecl>(Function) &&
-        !cast<CXXMethodDecl>(Function)->isStatic() &&
-        !isa<CXXConstructorDecl>(Function)) {
-      CXXMethodDecl *Method = cast<CXXMethodDecl>(Function);
-      R = PerformObjectArgumentInitialization(Args[0], /*Qualifier=*/nullptr,
-                                              Method, Method);
-    } else {
-      R = PerformCopyInitialization(InitializedEntity::InitializeParameter(
-                                        Context, Function->getParamDecl(I)),
+    R = S.PerformCopyInitialization(InitializedEntity::InitializeParameter(
+                                        S.Context, Function->getParamDecl(I)),
                                     SourceLocation(), Args[I]);
-    }
 
-    if (R.isInvalid()) {
-      InitializationFailed = true;
-      break;
-    }
+    if (R.isInvalid())
+      return false;
 
     ConvertedArgs.push_back(R.get());
   }
 
-  if (InitializationFailed || Trap.hasErrorOccurred())
-    return EnableIfAttrs[0];
+  if (Trap.hasErrorOccurred())
+    return false;
 
   // Push default arguments if needed.
   if (!Function->isVariadic() && Args.size() < Function->getNumParams()) {
     for (unsigned i = Args.size(), e = Function->getNumParams(); i != e; ++i) {
       ParmVarDecl *P = Function->getParamDecl(i);
-      ExprResult R = PerformCopyInitialization(
-          InitializedEntity::InitializeParameter(Context,
+      ExprResult R = S.PerformCopyInitialization(
+          InitializedEntity::InitializeParameter(S.Context,
                                                  Function->getParamDecl(i)),
           SourceLocation(),
           P->hasUninstantiatedDefaultArg() ? P->getUninstantiatedDefaultArg()
                                            : P->getDefaultArg());
-      if (R.isInvalid()) {
-        InitializationFailed = true;
-        break;
-      }
+      if (R.isInvalid())
+        return false;
       ConvertedArgs.push_back(R.get());
     }
 
-    if (InitializationFailed || Trap.hasErrorOccurred())
-      return EnableIfAttrs[0];
+    if (Trap.hasErrorOccurred())
+      return false;
   }
+  return true;
+}
+
+EnableIfAttr *Sema::CheckEnableIf(FunctionDecl *Function, ArrayRef<Expr *> Args,
+                                  bool MissingImplicitThis) {
+  SmallVector<EnableIfAttr *, 4> EnableIfAttrs =
+      getOrderedEnableIfAttrs(Function);
+  if (EnableIfAttrs.empty())
+    return nullptr;
+
+  SFINAETrap Trap(*this);
+  SmallVector<Expr *, 16> ConvertedArgs;
+  // FIXME: We should look into making enable_if late-parsed.
+  Expr *DiscardedThis;
+  if (!convertArgsForAvailabilityChecks(
+          *this, Function, /*ThisArg=*/nullptr, Args, Trap,
+          /*MissingImplicitThis=*/true, DiscardedThis, ConvertedArgs))
+    return EnableIfAttrs[0];
 
   for (auto *EIA : EnableIfAttrs) {
     APValue Result;
@@ -6170,6 +6263,87 @@ EnableIfAttr *Sema::CheckEnableIf(FunctionDecl *Function, ArrayRef<Expr *> Args,
   return nullptr;
 }
 
+static bool gatherDiagnoseIfAttrs(FunctionDecl *Function, bool ArgDependent,
+                                  SmallVectorImpl<DiagnoseIfAttr *> &Errors,
+                                  SmallVectorImpl<DiagnoseIfAttr *> &Nonfatal) {
+  for (auto *DIA : Function->specific_attrs<DiagnoseIfAttr>())
+    if (ArgDependent == DIA->getArgDependent()) {
+      if (DIA->isError())
+        Errors.push_back(DIA);
+      else
+        Nonfatal.push_back(DIA);
+    }
+
+  return !Errors.empty() || !Nonfatal.empty();
+}
+
+template <typename CheckFn>
+static DiagnoseIfAttr *
+checkDiagnoseIfAttrsWith(const SmallVectorImpl<DiagnoseIfAttr *> &Errors,
+                         SmallVectorImpl<DiagnoseIfAttr *> &Nonfatal,
+                         CheckFn &&IsSuccessful) {
+  // Note that diagnose_if attributes are late-parsed, so they appear in the
+  // correct order (unlike enable_if attributes).
+  auto ErrAttr = llvm::find_if(Errors, IsSuccessful);
+  if (ErrAttr != Errors.end())
+    return *ErrAttr;
+
+  llvm::erase_if(Nonfatal, [&](DiagnoseIfAttr *A) { return !IsSuccessful(A); });
+  return nullptr;
+}
+
+DiagnoseIfAttr *
+Sema::checkArgDependentDiagnoseIf(FunctionDecl *Function, ArrayRef<Expr *> Args,
+                                  SmallVectorImpl<DiagnoseIfAttr *> &Nonfatal,
+                                  bool MissingImplicitThis,
+                                  Expr *ThisArg) {
+  SmallVector<DiagnoseIfAttr *, 4> Errors;
+  if (!gatherDiagnoseIfAttrs(Function, /*ArgDependent=*/true, Errors, Nonfatal))
+    return nullptr;
+
+  SFINAETrap Trap(*this);
+  SmallVector<Expr *, 16> ConvertedArgs;
+  Expr *ConvertedThis;
+  if (!convertArgsForAvailabilityChecks(*this, Function, ThisArg, Args, Trap,
+                                        MissingImplicitThis, ConvertedThis,
+                                        ConvertedArgs))
+    return nullptr;
+
+  return checkDiagnoseIfAttrsWith(Errors, Nonfatal, [&](DiagnoseIfAttr *DIA) {
+    APValue Result;
+    // It's sane to use the same ConvertedArgs for any redecl of this function,
+    // since EvaluateWithSubstitution only cares about the position of each
+    // argument in the arg list, not the ParmVarDecl* it maps to.
+    if (!DIA->getCond()->EvaluateWithSubstitution(
+            Result, Context, DIA->getParent(), ConvertedArgs, ConvertedThis))
+      return false;
+    return Result.isInt() && Result.getInt().getBoolValue();
+  });
+}
+
+DiagnoseIfAttr *Sema::checkArgIndependentDiagnoseIf(
+    FunctionDecl *Function, SmallVectorImpl<DiagnoseIfAttr *> &Nonfatal) {
+  SmallVector<DiagnoseIfAttr *, 4> Errors;
+  if (!gatherDiagnoseIfAttrs(Function, /*ArgDependent=*/false, Errors,
+                             Nonfatal))
+    return nullptr;
+
+  return checkDiagnoseIfAttrsWith(Errors, Nonfatal, [&](DiagnoseIfAttr *DIA) {
+    bool Result;
+    return DIA->getCond()->EvaluateAsBooleanCondition(Result, Context) &&
+           Result;
+  });
+}
+
+void Sema::emitDiagnoseIfDiagnostic(SourceLocation Loc,
+                                    const DiagnoseIfAttr *DIA) {
+  auto Code = DIA->isError() ? diag::err_diagnose_if_succeeded
+                             : diag::warn_diagnose_if_succeeded;
+  Diag(Loc, Code) << DIA->getMessage();
+  Diag(DIA->getLocation(), diag::note_from_diagnose_if)
+      << DIA->getParent() << DIA->getCond()->getSourceRange();
+}
+
 /// \brief Add all of the function declarations in the given function set to
 /// the overload candidate set.
 void Sema::AddFunctionCandidates(const UnresolvedSetImpl &Fns,
@@ -6185,7 +6359,7 @@ void Sema::AddFunctionCandidates(const UnresolvedSetImpl &Fns,
         AddMethodCandidate(cast<CXXMethodDecl>(FD), F.getPair(),
                            cast<CXXMethodDecl>(FD)->getParent(),
                            Args[0]->getType(), Args[0]->Classify(Context),
-                           Args.slice(1), CandidateSet,
+                           Args[0], Args.slice(1), CandidateSet,
                            SuppressUserConversions, PartialOverloading);
       else
         AddOverloadCandidate(FD, F.getPair(), Args, CandidateSet,
@@ -6194,13 +6368,12 @@ void Sema::AddFunctionCandidates(const UnresolvedSetImpl &Fns,
       FunctionTemplateDecl *FunTmpl = cast<FunctionTemplateDecl>(D);
       if (isa<CXXMethodDecl>(FunTmpl->getTemplatedDecl()) &&
           !cast<CXXMethodDecl>(FunTmpl->getTemplatedDecl())->isStatic())
-        AddMethodTemplateCandidate(FunTmpl, F.getPair(),
-                              cast<CXXRecordDecl>(FunTmpl->getDeclContext()),
-                                   ExplicitTemplateArgs,
-                                   Args[0]->getType(),
-                                   Args[0]->Classify(Context), Args.slice(1),
-                                   CandidateSet, SuppressUserConversions,
-                                   PartialOverloading);
+        AddMethodTemplateCandidate(
+            FunTmpl, F.getPair(),
+            cast<CXXRecordDecl>(FunTmpl->getDeclContext()),
+            ExplicitTemplateArgs, Args[0]->getType(),
+            Args[0]->Classify(Context), Args[0], Args.slice(1), CandidateSet,
+            SuppressUserConversions, PartialOverloading);
       else
         AddTemplateOverloadCandidate(FunTmpl, F.getPair(),
                                      ExplicitTemplateArgs, Args,
@@ -6215,6 +6388,7 @@ void Sema::AddFunctionCandidates(const UnresolvedSetImpl &Fns,
 void Sema::AddMethodCandidate(DeclAccessPair FoundDecl,
                               QualType ObjectType,
                               Expr::Classification ObjectClassification,
+                              Expr *ThisArg,
                               ArrayRef<Expr *> Args,
                               OverloadCandidateSet& CandidateSet,
                               bool SuppressUserConversions) {
@@ -6230,12 +6404,12 @@ void Sema::AddMethodCandidate(DeclAccessPair FoundDecl,
     AddMethodTemplateCandidate(TD, FoundDecl, ActingContext,
                                /*ExplicitArgs*/ nullptr,
                                ObjectType, ObjectClassification,
-                               Args, CandidateSet,
+                               ThisArg, Args, CandidateSet,
                                SuppressUserConversions);
   } else {
     AddMethodCandidate(cast<CXXMethodDecl>(Decl), FoundDecl, ActingContext,
                        ObjectType, ObjectClassification,
-                       Args,
+                       ThisArg, Args,
                        CandidateSet, SuppressUserConversions);
   }
 }
@@ -6251,10 +6425,11 @@ void
 Sema::AddMethodCandidate(CXXMethodDecl *Method, DeclAccessPair FoundDecl,
                          CXXRecordDecl *ActingContext, QualType ObjectType,
                          Expr::Classification ObjectClassification,
-                         ArrayRef<Expr *> Args,
+                         Expr *ThisArg, ArrayRef<Expr *> Args,
                          OverloadCandidateSet &CandidateSet,
                          bool SuppressUserConversions,
-                         bool PartialOverloading) {
+                         bool PartialOverloading,
+                         ConversionSequenceList EarlyConversions) {
   const FunctionProtoType *Proto
     = dyn_cast<FunctionProtoType>(Method->getType()->getAs<FunctionType>());
   assert(Proto && "Methods without a prototype cannot be overloaded");
@@ -6275,7 +6450,8 @@ Sema::AddMethodCandidate(CXXMethodDecl *Method, DeclAccessPair FoundDecl,
   EnterExpressionEvaluationContext Unevaluated(*this, Sema::Unevaluated);
 
   // Add this candidate
-  OverloadCandidate &Candidate = CandidateSet.addCandidate(Args.size() + 1);
+  OverloadCandidate &Candidate =
+      CandidateSet.addCandidate(Args.size() + 1, EarlyConversions);
   Candidate.FoundDecl = FoundDecl;
   Candidate.Function = Method;
   Candidate.IsSurrogate = false;
@@ -6337,7 +6513,10 @@ Sema::AddMethodCandidate(CXXMethodDecl *Method, DeclAccessPair FoundDecl,
   // Determine the implicit conversion sequences for each of the
   // arguments.
   for (unsigned ArgIdx = 0; ArgIdx < Args.size(); ++ArgIdx) {
-    if (ArgIdx < NumParams) {
+    if (Candidate.Conversions[ArgIdx + 1].isInitialized()) {
+      // We already formed a conversion sequence for this parameter during
+      // template argument deduction.
+    } else if (ArgIdx < NumParams) {
       // (C++ 13.3.2p3): for F to be a viable function, there shall
       // exist for each argument an implicit conversion sequence
       // (13.3.3.1) that converts that argument to the corresponding
@@ -6368,6 +6547,9 @@ Sema::AddMethodCandidate(CXXMethodDecl *Method, DeclAccessPair FoundDecl,
     Candidate.DeductionFailure.Data = FailedAttr;
     return;
   }
+
+  initDiagnoseIfComplaint(*this, CandidateSet, Candidate, Method, Args,
+                          /*MissingImplicitThis=*/!ThisArg, ThisArg);
 }
 
 /// \brief Add a C++ member function template as a candidate to the candidate
@@ -6380,6 +6562,7 @@ Sema::AddMethodTemplateCandidate(FunctionTemplateDecl *MethodTmpl,
                                  TemplateArgumentListInfo *ExplicitTemplateArgs,
                                  QualType ObjectType,
                                  Expr::Classification ObjectClassification,
+                                 Expr *ThisArg,
                                  ArrayRef<Expr *> Args,
                                  OverloadCandidateSet& CandidateSet,
                                  bool SuppressUserConversions,
@@ -6398,19 +6581,30 @@ Sema::AddMethodTemplateCandidate(FunctionTemplateDecl *MethodTmpl,
   //   functions.
   TemplateDeductionInfo Info(CandidateSet.getLocation());
   FunctionDecl *Specialization = nullptr;
-  if (TemplateDeductionResult Result
-      = DeduceTemplateArguments(MethodTmpl, ExplicitTemplateArgs, Args,
-                                Specialization, Info, PartialOverloading)) {
-    OverloadCandidate &Candidate = CandidateSet.addCandidate();
+  ConversionSequenceList Conversions;
+  if (TemplateDeductionResult Result = DeduceTemplateArguments(
+          MethodTmpl, ExplicitTemplateArgs, Args, Specialization, Info,
+          PartialOverloading, [&](ArrayRef<QualType> ParamTypes) {
+            return CheckNonDependentConversions(
+                MethodTmpl, ParamTypes, Args, CandidateSet, Conversions,
+                SuppressUserConversions, ActingContext, ObjectType,
+                ObjectClassification);
+          })) {
+    OverloadCandidate &Candidate =
+        CandidateSet.addCandidate(Conversions.size(), Conversions);
     Candidate.FoundDecl = FoundDecl;
     Candidate.Function = MethodTmpl->getTemplatedDecl();
     Candidate.Viable = false;
-    Candidate.FailureKind = ovl_fail_bad_deduction;
     Candidate.IsSurrogate = false;
     Candidate.IgnoreObjectArgument = false;
     Candidate.ExplicitCallArguments = Args.size();
-    Candidate.DeductionFailure = MakeDeductionFailureInfo(Context, Result,
-                                                          Info);
+    if (Result == TDK_NonDependentConversionFailure)
+      Candidate.FailureKind = ovl_fail_bad_conversion;
+    else {
+      Candidate.FailureKind = ovl_fail_bad_deduction;
+      Candidate.DeductionFailure = MakeDeductionFailureInfo(Context, Result,
+                                                            Info);
+    }
     return;
   }
 
@@ -6420,8 +6614,9 @@ Sema::AddMethodTemplateCandidate(FunctionTemplateDecl *MethodTmpl,
   assert(isa<CXXMethodDecl>(Specialization) &&
          "Specialization is not a member function?");
   AddMethodCandidate(cast<CXXMethodDecl>(Specialization), FoundDecl,
-                     ActingContext, ObjectType, ObjectClassification, Args,
-                     CandidateSet, SuppressUserConversions, PartialOverloading);
+                     ActingContext, ObjectType, ObjectClassification,
+                     /*ThisArg=*/ThisArg, Args, CandidateSet,
+                     SuppressUserConversions, PartialOverloading, Conversions);
 }
 
 /// \brief Add a C++ function template specialization as a candidate
@@ -6449,19 +6644,29 @@ Sema::AddTemplateOverloadCandidate(FunctionTemplateDecl *FunctionTemplate,
   //   functions.
   TemplateDeductionInfo Info(CandidateSet.getLocation());
   FunctionDecl *Specialization = nullptr;
-  if (TemplateDeductionResult Result
-        = DeduceTemplateArguments(FunctionTemplate, ExplicitTemplateArgs, Args,
-                                  Specialization, Info, PartialOverloading)) {
-    OverloadCandidate &Candidate = CandidateSet.addCandidate();
+  ConversionSequenceList Conversions;
+  if (TemplateDeductionResult Result = DeduceTemplateArguments(
+          FunctionTemplate, ExplicitTemplateArgs, Args, Specialization, Info,
+          PartialOverloading, [&](ArrayRef<QualType> ParamTypes) {
+            return CheckNonDependentConversions(FunctionTemplate, ParamTypes,
+                                                Args, CandidateSet, Conversions,
+                                                SuppressUserConversions);
+          })) {
+    OverloadCandidate &Candidate =
+        CandidateSet.addCandidate(Conversions.size(), Conversions);
     Candidate.FoundDecl = FoundDecl;
     Candidate.Function = FunctionTemplate->getTemplatedDecl();
     Candidate.Viable = false;
-    Candidate.FailureKind = ovl_fail_bad_deduction;
     Candidate.IsSurrogate = false;
     Candidate.IgnoreObjectArgument = false;
     Candidate.ExplicitCallArguments = Args.size();
-    Candidate.DeductionFailure = MakeDeductionFailureInfo(Context, Result,
-                                                          Info);
+    if (Result == TDK_NonDependentConversionFailure)
+      Candidate.FailureKind = ovl_fail_bad_conversion;
+    else {
+      Candidate.FailureKind = ovl_fail_bad_deduction;
+      Candidate.DeductionFailure = MakeDeductionFailureInfo(Context, Result,
+                                                            Info);
+    }
     return;
   }
 
@@ -6469,7 +6674,64 @@ Sema::AddTemplateOverloadCandidate(FunctionTemplateDecl *FunctionTemplate,
   // deduction as a candidate.
   assert(Specialization && "Missing function template specialization?");
   AddOverloadCandidate(Specialization, FoundDecl, Args, CandidateSet,
-                       SuppressUserConversions, PartialOverloading);
+                       SuppressUserConversions, PartialOverloading,
+                       /*AllowExplicit*/false, Conversions);
+}
+
+/// Check that implicit conversion sequences can be formed for each argument
+/// whose corresponding parameter has a non-dependent type, per DR1391's
+/// [temp.deduct.call]p10.
+bool Sema::CheckNonDependentConversions(
+    FunctionTemplateDecl *FunctionTemplate, ArrayRef<QualType> ParamTypes,
+    ArrayRef<Expr *> Args, OverloadCandidateSet &CandidateSet,
+    ConversionSequenceList &Conversions, bool SuppressUserConversions,
+    CXXRecordDecl *ActingContext, QualType ObjectType,
+    Expr::Classification ObjectClassification) {
+  // FIXME: The cases in which we allow explicit conversions for constructor
+  // arguments never consider calling a constructor template. It's not clear
+  // that is correct.
+  const bool AllowExplicit = false;
+
+  auto *FD = FunctionTemplate->getTemplatedDecl();
+  auto *Method = dyn_cast<CXXMethodDecl>(FD);
+  bool HasThisConversion = Method && !isa<CXXConstructorDecl>(Method);
+  unsigned ThisConversions = HasThisConversion ? 1 : 0;
+
+  Conversions =
+      CandidateSet.allocateConversionSequences(ThisConversions + Args.size());
+
+  // Overload resolution is always an unevaluated context.
+  EnterExpressionEvaluationContext Unevaluated(*this, Sema::Unevaluated);
+
+  // For a method call, check the 'this' conversion here too. DR1391 doesn't
+  // require that, but this check should never result in a hard error, and
+  // overload resolution is permitted to sidestep instantiations.
+  if (HasThisConversion && !cast<CXXMethodDecl>(FD)->isStatic() &&
+      !ObjectType.isNull()) {
+    Conversions[0] = TryObjectArgumentInitialization(
+        *this, CandidateSet.getLocation(), ObjectType, ObjectClassification,
+        Method, ActingContext);
+    if (Conversions[0].isBad())
+      return true;
+  }
+
+  for (unsigned I = 0, N = std::min(ParamTypes.size(), Args.size()); I != N;
+       ++I) {
+    QualType ParamType = ParamTypes[I];
+    if (!ParamType->isDependentType()) {
+      Conversions[ThisConversions + I]
+        = TryCopyInitialization(*this, Args[I], ParamType,
+                                SuppressUserConversions,
+                                /*InOverloadResolution=*/true,
+                                /*AllowObjCWritebackConversion=*/
+                                  getLangOpts().ObjCAutoRefCount,
+                                AllowExplicit);
+      if (Conversions[ThisConversions + I].isBad())
+        return true;
+    }
+  }
+
+  return false;
 }
 
 /// Determine whether this is an allowable conversion from the result
@@ -6677,6 +6939,8 @@ Sema::AddConversionCandidate(CXXConversionDecl *Conversion,
     Candidate.DeductionFailure.Data = FailedAttr;
     return;
   }
+
+  initDiagnoseIfComplaint(*this, CandidateSet, Candidate, Conversion, None, false, From);
 }
 
 /// \brief Adds a conversion function template specialization
@@ -6829,6 +7093,8 @@ void Sema::AddSurrogateCandidate(CXXConversionDecl *Conversion,
     Candidate.DeductionFailure.Data = FailedAttr;
     return;
   }
+
+  initDiagnoseIfComplaint(*this, CandidateSet, Candidate, Conversion, None);
 }
 
 /// \brief Add overload candidates for overloaded operators that are
@@ -6877,10 +7143,8 @@ void Sema::AddMemberOperatorCandidates(OverloadedOperatorKind Op,
          Oper != OperEnd;
          ++Oper)
       AddMethodCandidate(Oper.getPair(), Args[0]->getType(),
-                         Args[0]->Classify(Context), 
-                         Args.slice(1),
-                         CandidateSet,
-                         /* SuppressUserConversions = */ false);
+                         Args[0]->Classify(Context), Args[0], Args.slice(1),
+                         CandidateSet, /*SuppressUserConversions=*/false);
   }
 }
 
@@ -8708,8 +8972,8 @@ bool clang::isBetterOverloadCandidate(Sema &S, const OverloadCandidate &Cand1,
 
   // Define functions that don't require ill-formed conversions for a given
   // argument to be better candidates than functions that do.
-  unsigned NumArgs = Cand1.NumConversions;
-  assert(Cand2.NumConversions == NumArgs && "Overload candidate mismatch");
+  unsigned NumArgs = Cand1.Conversions.size();
+  assert(Cand2.Conversions.size() == NumArgs && "Overload candidate mismatch");
   bool HasBetterConversion = false;
   for (unsigned ArgIdx = StartArg; ArgIdx < NumArgs; ++ArgIdx) {
     bool Cand1Bad = IsIllFormedConversion(Cand1.Conversions[ArgIdx]);
@@ -8911,6 +9175,17 @@ void Sema::diagnoseEquivalentInternalLinkageDeclarations(
   }
 }
 
+static bool isCandidateUnavailableDueToDiagnoseIf(const OverloadCandidate &OC) {
+  ArrayRef<DiagnoseIfAttr *> Info = OC.getDiagnoseIfInfo();
+  if (!Info.empty() && Info[0]->isError())
+    return true;
+
+  assert(llvm::all_of(Info,
+                      [](const DiagnoseIfAttr *A) { return !A->isError(); }) &&
+         "DiagnoseIf info shouldn't have mixed warnings and errors.");
+  return false;
+}
+
 /// \brief Computes the best viable function (C++ 13.3.3)
 /// within an overload candidate set.
 ///
@@ -8989,13 +9264,19 @@ OverloadCandidateSet::BestViableFunction(Sema &S, SourceLocation Loc,
   // Best is the best viable function.
   if (Best->Function &&
       (Best->Function->isDeleted() ||
-       S.isFunctionConsideredUnavailable(Best->Function)))
+       S.isFunctionConsideredUnavailable(Best->Function) ||
+       isCandidateUnavailableDueToDiagnoseIf(*Best)))
     return OR_Deleted;
 
   if (!EquivalentCands.empty())
     S.diagnoseEquivalentInternalLinkageDeclarations(Loc, Best->Function,
                                                     EquivalentCands);
 
+  for (const auto *W : Best->getDiagnoseIfInfo()) {
+    assert(W->isWarning() && "Errors should've been caught earlier!");
+    S.emitDiagnoseIfDiagnostic(Loc, W);
+  }
+
   return OR_Success;
 }
 
@@ -9836,7 +10117,7 @@ static void DiagnoseFailedEnableIfAttr(Sema &S, OverloadCandidate *Cand) {
   EnableIfAttr *Attr = static_cast<EnableIfAttr*>(Cand->DeductionFailure.Data);
 
   S.Diag(Callee->getLocation(),
-         diag::note_ovl_candidate_disabled_by_enable_if_attr)
+         diag::note_ovl_candidate_disabled_by_function_cond_attr)
       << Attr->getCond()->getSourceRange() << Attr->getMessage();
 }
 
@@ -9866,21 +10147,28 @@ static void NoteFunctionCandidate(Sema &S, OverloadCandidate *Cand,
   FunctionDecl *Fn = Cand->Function;
 
   // Note deleted candidates, but only if they're viable.
-  if (Cand->Viable && (Fn->isDeleted() ||
-      S.isFunctionConsideredUnavailable(Fn))) {
-    std::string FnDesc;
-    OverloadCandidateKind FnKind =
+  if (Cand->Viable) {
+    if (Fn->isDeleted() || S.isFunctionConsideredUnavailable(Fn)) {
+      std::string FnDesc;
+      OverloadCandidateKind FnKind =
         ClassifyOverloadCandidate(S, Cand->FoundDecl, Fn, FnDesc);
 
-    S.Diag(Fn->getLocation(), diag::note_ovl_candidate_deleted)
-      << FnKind << FnDesc
-      << (Fn->isDeleted() ? (Fn->isDeletedAsWritten() ? 1 : 2) : 0);
-    MaybeEmitInheritedConstructorNote(S, Cand->FoundDecl);
-    return;
-  }
+      S.Diag(Fn->getLocation(), diag::note_ovl_candidate_deleted)
+        << FnKind << FnDesc
+        << (Fn->isDeleted() ? (Fn->isDeletedAsWritten() ? 1 : 2) : 0);
+      MaybeEmitInheritedConstructorNote(S, Cand->FoundDecl);
+      return;
+    }
+    if (isCandidateUnavailableDueToDiagnoseIf(*Cand)) {
+      auto *A = Cand->DiagnoseIfInfo.get<DiagnoseIfAttr *>();
+      assert(A->isError() && "Non-error diagnose_if disables a candidate?");
+      S.Diag(Cand->Function->getLocation(),
+             diag::note_ovl_candidate_disabled_by_function_cond_attr)
+          << A->getCond()->getSourceRange() << A->getMessage();
+      return;
+    }
 
-  // We don't really have anything else to say about viable candidates.
-  if (Cand->Viable) {
+    // We don't really have anything else to say about viable candidates.
     S.NoteOverloadCandidate(Cand->FoundDecl, Fn);
     return;
   }
@@ -9908,7 +10196,7 @@ static void NoteFunctionCandidate(Sema &S, OverloadCandidate *Cand,
 
   case ovl_fail_bad_conversion: {
     unsigned I = (Cand->IgnoreObjectArgument ? 1 : 0);
-    for (unsigned N = Cand->NumConversions; I != N; ++I)
+    for (unsigned N = Cand->Conversions.size(); I != N; ++I)
       if (Cand->Conversions[I].isBad())
         return DiagnoseBadConversion(S, Cand, I, TakingCandidateAddress);
 
@@ -9927,6 +10215,12 @@ static void NoteFunctionCandidate(Sema &S, OverloadCandidate *Cand,
   case ovl_fail_ext_disabled:
     return DiagnoseOpenCLExtensionDisabled(S, Cand);
 
+  case ovl_fail_inhctor_slice:
+    S.Diag(Fn->getLocation(),
+           diag::note_ovl_candidate_inherited_constructor_slice);
+    MaybeEmitInheritedConstructorNote(S, Cand->FoundDecl);
+    return;
+
   case ovl_fail_addr_not_available: {
     bool Available = checkAddressOfCandidateIsAvailable(S, Cand->Function);
     (void)Available;
@@ -9971,12 +10265,12 @@ static void NoteSurrogateCandidate(Sema &S, OverloadCandidate *Cand) {
 static void NoteBuiltinOperatorCandidate(Sema &S, StringRef Opc,
                                          SourceLocation OpLoc,
                                          OverloadCandidate *Cand) {
-  assert(Cand->NumConversions <= 2 && "builtin operator is not binary");
+  assert(Cand->Conversions.size() <= 2 && "builtin operator is not binary");
   std::string TypeStr("operator");
   TypeStr += Opc;
   TypeStr += "(";
   TypeStr += Cand->BuiltinTypes.ParamTypes[0].getAsString();
-  if (Cand->NumConversions == 1) {
+  if (Cand->Conversions.size() == 1) {
     TypeStr += ")";
     S.Diag(OpLoc, diag::note_ovl_builtin_unary_candidate) << TypeStr;
   } else {
@@ -9989,9 +10283,7 @@ static void NoteBuiltinOperatorCandidate(Sema &S, StringRef Opc,
 
 static void NoteAmbiguousUserConversions(Sema &S, SourceLocation OpLoc,
                                          OverloadCandidate *Cand) {
-  unsigned NoOperands = Cand->NumConversions;
-  for (unsigned ArgIdx = 0; ArgIdx < NoOperands; ++ArgIdx) {
-    const ImplicitConversionSequence &ICS = Cand->Conversions[ArgIdx];
+  for (const ImplicitConversionSequence &ICS : Cand->Conversions) {
     if (ICS.isBad()) break; // all meaningless after first invalid
     if (!ICS.isAmbiguous()) continue;
 
@@ -10011,7 +10303,8 @@ static SourceLocation GetLocationForCandidate(const OverloadCandidate *Cand) {
 static unsigned RankDeductionFailure(const DeductionFailureInfo &DFI) {
   switch ((Sema::TemplateDeductionResult)DFI.Result) {
   case Sema::TDK_Success:
-    llvm_unreachable("TDK_success while diagnosing bad deduction");
+  case Sema::TDK_NonDependentConversionFailure:
+    llvm_unreachable("non-deduction failure while diagnosing bad deduction");
 
   case Sema::TDK_Invalid:
   case Sema::TDK_Incomplete:
@@ -10114,11 +10407,11 @@ struct CompareOverloadCandidatesForDisplay {
 
         // If there's any ordering between the defined conversions...
         // FIXME: this might not be transitive.
-        assert(L->NumConversions == R->NumConversions);
+        assert(L->Conversions.size() == R->Conversions.size());
 
         int leftBetter = 0;
         unsigned I = (L->IgnoreObjectArgument || R->IgnoreObjectArgument);
-        for (unsigned E = L->NumConversions; I != E; ++I) {
+        for (unsigned E = L->Conversions.size(); I != E; ++I) {
           switch (CompareImplicitConversionSequences(S, Loc,
                                                      L->Conversions[I],
                                                      R->Conversions[I])) {
@@ -10167,7 +10460,8 @@ struct CompareOverloadCandidatesForDisplay {
 }
 
 /// CompleteNonViableCandidate - Normally, overload resolution only
-/// computes up to the first. Produces the FixIt set if possible.
+/// computes up to the first bad conversion. Produces the FixIt set if
+/// possible.
 static void CompleteNonViableCandidate(Sema &S, OverloadCandidate *Cand,
                                        ArrayRef<Expr *> Args) {
   assert(!Cand->Viable);
@@ -10180,30 +10474,24 @@ static void CompleteNonViableCandidate(Sema &S, OverloadCandidate *Cand,
   // Use a implicit copy initialization to check conversion fixes.
   Cand->Fix.setConversionChecker(TryCopyInitialization);
 
-  // Skip forward to the first bad conversion.
-  unsigned ConvIdx = (Cand->IgnoreObjectArgument ? 1 : 0);
-  unsigned ConvCount = Cand->NumConversions;
-  while (true) {
+  // Attempt to fix the bad conversion.
+  unsigned ConvCount = Cand->Conversions.size();
+  for (unsigned ConvIdx = (Cand->IgnoreObjectArgument ? 1 : 0); /**/;
+       ++ConvIdx) {
     assert(ConvIdx != ConvCount && "no bad conversion in candidate");
-    ConvIdx++;
-    if (Cand->Conversions[ConvIdx - 1].isBad()) {
-      Unfixable = !Cand->TryToFixBadConversion(ConvIdx - 1, S);
+    if (Cand->Conversions[ConvIdx].isInitialized() &&
+        Cand->Conversions[ConvIdx].isBad()) {
+      Unfixable = !Cand->TryToFixBadConversion(ConvIdx, S);
       break;
     }
   }
 
-  if (ConvIdx == ConvCount)
-    return;
-
-  assert(!Cand->Conversions[ConvIdx].isInitialized() &&
-         "remaining conversion is initialized?");
-
   // FIXME: this should probably be preserved from the overload
   // operation somehow.
   bool SuppressUserConversions = false;
 
-  const FunctionProtoType* Proto;
-  unsigned ArgIdx = ConvIdx;
+  const FunctionProtoType *Proto;
+  unsigned ArgIdx = 0;
 
   if (Cand->IsSurrogate) {
     QualType ConvType
@@ -10211,40 +10499,56 @@ static void CompleteNonViableCandidate(Sema &S, OverloadCandidate *Cand,
     if (const PointerType *ConvPtrType = ConvType->getAs<PointerType>())
       ConvType = ConvPtrType->getPointeeType();
     Proto = ConvType->getAs<FunctionProtoType>();
-    ArgIdx--;
+    ArgIdx = 1;
   } else if (Cand->Function) {
     Proto = Cand->Function->getType()->getAs<FunctionProtoType>();
     if (isa<CXXMethodDecl>(Cand->Function) &&
         !isa<CXXConstructorDecl>(Cand->Function))
-      ArgIdx--;
+      ArgIdx = 1;
   } else {
     // Builtin binary operator with a bad first conversion.
     assert(ConvCount <= 3);
-    for (; ConvIdx != ConvCount; ++ConvIdx)
-      Cand->Conversions[ConvIdx]
-        = TryCopyInitialization(S, Args[ConvIdx],
-                                Cand->BuiltinTypes.ParamTypes[ConvIdx],
-                                SuppressUserConversions,
-                                /*InOverloadResolution*/ true,
-                                /*AllowObjCWritebackConversion=*/
-                                  S.getLangOpts().ObjCAutoRefCount);
+    for (unsigned ConvIdx = (Cand->IgnoreObjectArgument ? 1 : 0);
+         ConvIdx != ConvCount; ++ConvIdx) {
+      if (Cand->Conversions[ConvIdx].isInitialized())
+        continue;
+      if (Cand->BuiltinTypes.ParamTypes[ConvIdx]->isDependentType())
+        Cand->Conversions[ConvIdx].setAsIdentityConversion(
+            Args[ConvIdx]->getType());
+      else
+        Cand->Conversions[ConvIdx] = TryCopyInitialization(
+            S, Args[ConvIdx], Cand->BuiltinTypes.ParamTypes[ConvIdx],
+            SuppressUserConversions,
+            /*InOverloadResolution*/ true,
+            /*AllowObjCWritebackConversion=*/
+            S.getLangOpts().ObjCAutoRefCount);
+      // FIXME: If the conversion is bad, try to fix it.
+    }
     return;
   }
 
   // Fill in the rest of the conversions.
   unsigned NumParams = Proto->getNumParams();
-  for (; ConvIdx != ConvCount; ++ConvIdx, ++ArgIdx) {
-    if (ArgIdx < NumParams) {
-      Cand->Conversions[ConvIdx] = TryCopyInitialization(
-          S, Args[ArgIdx], Proto->getParamType(ArgIdx), SuppressUserConversions,
-          /*InOverloadResolution=*/true,
-          /*AllowObjCWritebackConversion=*/
-          S.getLangOpts().ObjCAutoRefCount);
-      // Store the FixIt in the candidate if it exists.
-      if (!Unfixable && Cand->Conversions[ConvIdx].isBad())
-        Unfixable = !Cand->TryToFixBadConversion(ConvIdx, S);
-    }
-    else
+  for (unsigned ConvIdx = (Cand->IgnoreObjectArgument ? 1 : 0);
+       ConvIdx != ConvCount; ++ConvIdx, ++ArgIdx) {
+    if (Cand->Conversions[ConvIdx].isInitialized()) {
+      // Found the bad conversion.
+    } else if (ArgIdx < NumParams) {
+      if (Proto->getParamType(ArgIdx)->isDependentType())
+        Cand->Conversions[ConvIdx].setAsIdentityConversion(
+            Args[ArgIdx]->getType());
+      else {
+        Cand->Conversions[ConvIdx] =
+            TryCopyInitialization(S, Args[ArgIdx], Proto->getParamType(ArgIdx),
+                                  SuppressUserConversions,
+                                  /*InOverloadResolution=*/true,
+                                  /*AllowObjCWritebackConversion=*/
+                                  S.getLangOpts().ObjCAutoRefCount);
+        // Store the FixIt in the candidate if it exists.
+        if (!Unfixable && Cand->Conversions[ConvIdx].isBad())
+          Unfixable = !Cand->TryToFixBadConversion(ConvIdx, S);
+      }
+    } else
       Cand->Conversions[ConvIdx].setEllipsis();
   }
 }
@@ -12429,6 +12733,16 @@ Sema::BuildCallToMemberFunction(Scope *S, Expr *MemExprE,
       TemplateArgs = &TemplateArgsBuffer;
     }
 
+    // Poor-programmer's Lazy<Expr *>; isImplicitAccess requires stripping
+    // parens/casts, which would be nice to avoid potentially doing multiple
+    // times.
+    llvm::Optional<Expr *> UnresolvedBase;
+    auto GetUnresolvedBase = [&] {
+      if (!UnresolvedBase.hasValue())
+        UnresolvedBase =
+          UnresExpr->isImplicitAccess() ? nullptr : UnresExpr->getBase();
+      return *UnresolvedBase;
+    };
     for (UnresolvedMemberExpr::decls_iterator I = UnresExpr->decls_begin(),
            E = UnresExpr->decls_end(); I != E; ++I) {
 
@@ -12449,14 +12763,15 @@ Sema::BuildCallToMemberFunction(Scope *S, Expr *MemExprE,
           continue;
 
         AddMethodCandidate(Method, I.getPair(), ActingDC, ObjectType,
-                           ObjectClassification, Args, CandidateSet,
+                           ObjectClassification,
+                           /*ThisArg=*/GetUnresolvedBase(), Args, CandidateSet,
                            /*SuppressUserConversions=*/false);
       } else {
-        AddMethodTemplateCandidate(cast<FunctionTemplateDecl>(Func),
-                                   I.getPair(), ActingDC, TemplateArgs,
-                                   ObjectType,  ObjectClassification,
-                                   Args, CandidateSet,
-                                   /*SuppressUsedConversions=*/false);
+        AddMethodTemplateCandidate(
+            cast<FunctionTemplateDecl>(Func), I.getPair(), ActingDC,
+            TemplateArgs, ObjectType, ObjectClassification,
+            /*ThisArg=*/GetUnresolvedBase(), Args, CandidateSet,
+            /*SuppressUsedConversions=*/false);
       }
     }
 
@@ -12569,10 +12884,20 @@ Sema::BuildCallToMemberFunction(Scope *S, Expr *MemExprE,
            diag::err_ovl_no_viable_member_function_in_call)
           << Method << Method->getSourceRange();
       Diag(Method->getLocation(),
-           diag::note_ovl_candidate_disabled_by_enable_if_attr)
+           diag::note_ovl_candidate_disabled_by_function_cond_attr)
           << Attr->getCond()->getSourceRange() << Attr->getMessage();
       return ExprError();
     }
+
+    SmallVector<DiagnoseIfAttr *, 4> Nonfatal;
+    if (const DiagnoseIfAttr *Attr = checkArgDependentDiagnoseIf(
+            Method, Args, Nonfatal, false, MemE->getBase())) {
+      emitDiagnoseIfDiagnostic(MemE->getMemberLoc(), Attr);
+      return ExprError();
+    }
+
+    for (const auto *Attr : Nonfatal)
+      emitDiagnoseIfDiagnostic(MemE->getMemberLoc(), Attr);
   }
 
   if ((isa<CXXConstructorDecl>(CurContext) || 
@@ -12652,7 +12977,7 @@ Sema::BuildCallToObjectOfClassType(Scope *S, Expr *Obj,
        Oper != OperEnd; ++Oper) {
     AddMethodCandidate(Oper.getPair(), Object.get()->getType(),
                        Object.get()->Classify(Context),
-                       Args, CandidateSet,
+                       Object.get(), Args, CandidateSet,
                        /*SuppressUserConversions=*/ false);
   }
 
@@ -12928,7 +13253,8 @@ Sema::BuildOverloadedArrowExpr(Scope *S, Expr *Base, SourceLocation OpLoc,
   for (LookupResult::iterator Oper = R.begin(), OperEnd = R.end();
        Oper != OperEnd; ++Oper) {
     AddMethodCandidate(Oper.getPair(), Base->getType(), Base->Classify(Context),
-                       None, CandidateSet, /*SuppressUserConversions=*/false);
+                       Base, None, CandidateSet,
+                       /*SuppressUserConversions=*/false);
   }
 
   bool HadMultipleCandidates = (CandidateSet.size() > 1);
diff --git a/lib/Sema/SemaTemplate.cpp b/lib/Sema/SemaTemplate.cpp
index 66a10ef7993e..795e6025d96f 100644
--- a/lib/Sema/SemaTemplate.cpp
+++ b/lib/Sema/SemaTemplate.cpp
@@ -5158,6 +5158,11 @@ ExprResult Sema::CheckTemplateArgument(NonTypeTemplateParmDecl *Param,
     return Arg;
   }
 
+  // The initialization of the parameter from the argument is
+  // a constant-evaluated context.
+  EnterExpressionEvaluationContext ConstantEvaluated(*this,
+                                                     Sema::ConstantEvaluated);
+
   if (getLangOpts().CPlusPlus1z) {
     // C++1z [temp.arg.nontype]p1:
     //   A template-argument for a non-type template parameter shall be
diff --git a/lib/Sema/SemaTemplateDeduction.cpp b/lib/Sema/SemaTemplateDeduction.cpp
index b79904c0a703..93e796ee9668 100644
--- a/lib/Sema/SemaTemplateDeduction.cpp
+++ b/lib/Sema/SemaTemplateDeduction.cpp
@@ -669,6 +669,19 @@ public:
       Info.PendingDeducedPacks[Pack.Index] = Pack.Outer;
   }
 
+  /// Determine whether this pack has already been partially expanded into a
+  /// sequence of (prior) function parameters / template arguments.
+  bool isPartiallyExpanded() {
+    if (Packs.size() != 1 || !S.CurrentInstantiationScope)
+      return false;
+
+    auto *PartiallySubstitutedPack =
+        S.CurrentInstantiationScope->getPartiallySubstitutedPack();
+    return PartiallySubstitutedPack &&
+           getDepthAndIndex(PartiallySubstitutedPack) ==
+               std::make_pair(Info.getDeducedDepth(), Packs.front().Index);
+  }
+
   /// Move to deducing the next element in each pack that is being deduced.
   void nextPackElement() {
     // Capture the deduced template arguments for each parameter pack expanded
@@ -2552,6 +2565,12 @@ static bool isSimpleTemplateIdType(QualType T) {
   return false;
 }
 
+static void
+MarkUsedTemplateParameters(ASTContext &Ctx, QualType T,
+                           bool OnlyDeduced,
+                           unsigned Level,
+                           llvm::SmallBitVector &Deduced);
+
 /// \brief Substitute the explicitly-provided template arguments into the
 /// given function template according to C++ [temp.arg.explicit].
 ///
@@ -2613,7 +2632,7 @@ Sema::SubstituteExplicitTemplateArguments(
   // Enter a new template instantiation context where we check the
   // explicitly-specified template arguments against this function template,
   // and then substitute them into the function parameter types.
-  SmallVector<TemplateArgument, 4> DeducedArgs(Deduced.begin(), Deduced.end());
+  SmallVector<TemplateArgument, 4> DeducedArgs;
   InstantiatingTemplate Inst(*this, Info.getLocation(), FunctionTemplate,
                              DeducedArgs,
            ActiveTemplateInstantiation::ExplicitTemplateArgumentSubstitution,
@@ -2893,14 +2912,13 @@ static unsigned getPackIndexForParam(Sema &S,
 ///
 /// \param OriginalCallArgs If non-NULL, the original call arguments against
 /// which the deduced argument types should be compared.
-Sema::TemplateDeductionResult
-Sema::FinishTemplateArgumentDeduction(FunctionTemplateDecl *FunctionTemplate,
-                       SmallVectorImpl<DeducedTemplateArgument> &Deduced,
-                                      unsigned NumExplicitlySpecified,
-                                      FunctionDecl *&Specialization,
-                                      TemplateDeductionInfo &Info,
-        SmallVectorImpl<OriginalCallArg> const *OriginalCallArgs,
-                                      bool PartialOverloading) {
+Sema::TemplateDeductionResult Sema::FinishTemplateArgumentDeduction(
+    FunctionTemplateDecl *FunctionTemplate,
+    SmallVectorImpl<DeducedTemplateArgument> &Deduced,
+    unsigned NumExplicitlySpecified, FunctionDecl *&Specialization,
+    TemplateDeductionInfo &Info,
+    SmallVectorImpl<OriginalCallArg> const *OriginalCallArgs,
+    bool PartialOverloading, llvm::function_ref<bool()> CheckNonDependent) {
   // Unevaluated SFINAE context.
   EnterExpressionEvaluationContext Unevaluated(*this, Sema::Unevaluated);
   SFINAETrap Trap(*this);
@@ -2927,6 +2945,18 @@ Sema::FinishTemplateArgumentDeduction(FunctionTemplateDecl *FunctionTemplate,
           PartialOverloading))
     return Result;
 
+  // C++ [temp.deduct.call]p10: [DR1391]
+  //   If deduction succeeds for all parameters that contain
+  //   template-parameters that participate in template argument deduction,
+  //   and all template arguments are explicitly specified, deduced, or
+  //   obtained from default template arguments, remaining parameters are then
+  //   compared with the corresponding arguments. For each remaining parameter
+  //   P with a type that was non-dependent before substitution of any
+  //   explicitly-specified template arguments, if the corresponding argument
+  //   A cannot be implicitly converted to P, deduction fails.
+  if (CheckNonDependent())
+    return TDK_NonDependentConversionFailure;
+
   // Form the template argument list from the deduced template arguments.
   TemplateArgumentList *DeducedArgumentList
     = TemplateArgumentList::CreateCopy(Context, Builder);
@@ -3373,12 +3403,19 @@ static Sema::TemplateDeductionResult DeduceTemplateArgumentsFromCallArgument(
 /// \param Info the argument will be updated to provide additional information
 /// about template argument deduction.
 ///
+/// \param CheckNonDependent A callback to invoke to check conversions for
+/// non-dependent parameters, between deduction and substitution, per DR1391.
+/// If this returns true, substitution will be skipped and we return
+/// TDK_NonDependentConversionFailure. The callback is passed the parameter
+/// types (after substituting explicit template arguments).
+///
 /// \returns the result of template argument deduction.
 Sema::TemplateDeductionResult Sema::DeduceTemplateArguments(
     FunctionTemplateDecl *FunctionTemplate,
     TemplateArgumentListInfo *ExplicitTemplateArgs, ArrayRef<Expr *> Args,
     FunctionDecl *&Specialization, TemplateDeductionInfo &Info,
-    bool PartialOverloading) {
+    bool PartialOverloading,
+    llvm::function_ref<bool(ArrayRef<QualType>)> CheckNonDependent) {
   if (FunctionTemplate->isInvalidDecl())
     return TDK_Invalid;
 
@@ -3389,7 +3426,6 @@ Sema::TemplateDeductionResult Sema::DeduceTemplateArguments(
   //   Template argument deduction is done by comparing each function template
   //   parameter type (call it P) with the type of the corresponding argument
   //   of the call (call it A) as described below.
-  unsigned CheckArgs = Args.size();
   if (Args.size() < Function->getMinRequiredArguments() && !PartialOverloading)
     return TDK_TooFewArguments;
   else if (TooManyArguments(NumParams, Args.size(), PartialOverloading)) {
@@ -3397,9 +3433,7 @@ Sema::TemplateDeductionResult Sema::DeduceTemplateArguments(
       = Function->getType()->getAs<FunctionProtoType>();
     if (Proto->isTemplateVariadic())
       /* Do nothing */;
-    else if (Proto->isVariadic())
-      CheckArgs = NumParams;
-    else
+    else if (!Proto->isVariadic())
       return TDK_TooManyArguments;
   }
 
@@ -3409,7 +3443,7 @@ Sema::TemplateDeductionResult Sema::DeduceTemplateArguments(
   TemplateParameterList *TemplateParams
     = FunctionTemplate->getTemplateParameters();
   SmallVector<DeducedTemplateArgument, 4> Deduced;
-  SmallVector<QualType, 4> ParamTypes;
+  SmallVector<QualType, 8> ParamTypes;
   unsigned NumExplicitlySpecified = 0;
   if (ExplicitTemplateArgs) {
     TemplateDeductionResult Result =
@@ -3429,7 +3463,7 @@ Sema::TemplateDeductionResult Sema::DeduceTemplateArguments(
       ParamTypes.push_back(Function->getParamDecl(I)->getType());
   }
 
-  SmallVector<OriginalCallArg, 4> OriginalCallArgs;
+  SmallVector<OriginalCallArg, 8> OriginalCallArgs;
 
   // Deduce an argument of type ParamType from an expression with index ArgIdx.
   auto DeduceCallArgument = [&](QualType ParamType, unsigned ArgIdx) {
@@ -3448,6 +3482,7 @@ Sema::TemplateDeductionResult Sema::DeduceTemplateArguments(
 
   // Deduce template arguments from the function parameters.
   Deduced.resize(TemplateParams->size());
+  SmallVector<QualType, 8> ParamTypesForArgChecking;
   for (unsigned ParamIdx = 0, NumParamTypes = ParamTypes.size(), ArgIdx = 0;
        ParamIdx != NumParamTypes; ++ParamIdx) {
     QualType ParamType = ParamTypes[ParamIdx];
@@ -3456,51 +3491,68 @@ Sema::TemplateDeductionResult Sema::DeduceTemplateArguments(
         dyn_cast<PackExpansionType>(ParamType);
     if (!ParamExpansion) {
       // Simple case: matching a function parameter to a function argument.
-      if (ArgIdx >= CheckArgs)
+      if (ArgIdx >= Args.size())
         break;
 
+      ParamTypesForArgChecking.push_back(ParamType);
       if (auto Result = DeduceCallArgument(ParamType, ArgIdx++))
         return Result;
 
       continue;
     }
 
+    QualType ParamPattern = ParamExpansion->getPattern();
+    PackDeductionScope PackScope(*this, TemplateParams, Deduced, Info,
+                                 ParamPattern);
+
     // C++0x [temp.deduct.call]p1:
     //   For a function parameter pack that occurs at the end of the
     //   parameter-declaration-list, the type A of each remaining argument of
     //   the call is compared with the type P of the declarator-id of the
     //   function parameter pack. Each comparison deduces template arguments
     //   for subsequent positions in the template parameter packs expanded by
-    //   the function parameter pack. For a function parameter pack that does
-    //   not occur at the end of the parameter-declaration-list, the type of
-    //   the parameter pack is a non-deduced context.
-    // FIXME: This does not say that subsequent parameters are also non-deduced.
-    // See also DR1388 / DR1399, which effectively says we should keep deducing
-    // after the pack.
-    if (ParamIdx + 1 < NumParamTypes)
-      break;
-
-    QualType ParamPattern = ParamExpansion->getPattern();
-    PackDeductionScope PackScope(*this, TemplateParams, Deduced, Info,
-                                 ParamPattern);
-
-    for (; ArgIdx < Args.size(); PackScope.nextPackElement(), ++ArgIdx)
-      if (auto Result = DeduceCallArgument(ParamPattern, ArgIdx))
-        return Result;
+    //   the function parameter pack. When a function parameter pack appears
+    //   in a non-deduced context [not at the end of the list], the type of
+    //   that parameter pack is never deduced.
+    //
+    // FIXME: The above rule allows the size of the parameter pack to change
+    // after we skip it (in the non-deduced case). That makes no sense, so
+    // we instead notionally deduce the pack against N arguments, where N is
+    // the length of the explicitly-specified pack if it's expanded by the
+    // parameter pack and 0 otherwise, and we treat each deduction as a
+    // non-deduced context.
+    if (ParamIdx + 1 == NumParamTypes) {
+      for (; ArgIdx < Args.size(); PackScope.nextPackElement(), ++ArgIdx) {
+        ParamTypesForArgChecking.push_back(ParamPattern);
+        if (auto Result = DeduceCallArgument(ParamPattern, ArgIdx))
+          return Result;
+      }
+    } else {
+      // If the parameter type contains an explicitly-specified pack that we
+      // could not expand, skip the number of parameters notionally created
+      // by the expansion.
+      Optional<unsigned> NumExpansions = ParamExpansion->getNumExpansions();
+      if (NumExpansions && !PackScope.isPartiallyExpanded()) {
+        for (unsigned I = 0; I != *NumExpansions && ArgIdx < Args.size();
+             ++I, ++ArgIdx) {
+          ParamTypesForArgChecking.push_back(ParamPattern);
+          // FIXME: Should we add OriginalCallArgs for these? What if the
+          // corresponding argument is a list?
+          PackScope.nextPackElement();
+        }
+      }
+    }
 
     // Build argument packs for each of the parameter packs expanded by this
     // pack expansion.
     if (auto Result = PackScope.finish())
       return Result;
-
-    // After we've matching against a parameter pack, we're done.
-    break;
   }
 
-  return FinishTemplateArgumentDeduction(FunctionTemplate, Deduced,
-                                         NumExplicitlySpecified, Specialization,
-                                         Info, &OriginalCallArgs,
-                                         PartialOverloading);
+  return FinishTemplateArgumentDeduction(
+      FunctionTemplate, Deduced, NumExplicitlySpecified, Specialization, Info,
+      &OriginalCallArgs, PartialOverloading,
+      [&]() { return CheckNonDependent(ParamTypesForArgChecking); });
 }
 
 QualType Sema::adjustCCAndNoReturn(QualType ArgFunctionType,
@@ -4230,12 +4282,6 @@ bool Sema::DeduceReturnType(FunctionDecl *FD, SourceLocation Loc,
   return StillUndeduced;
 }
 
-static void
-MarkUsedTemplateParameters(ASTContext &Ctx, QualType T,
-                           bool OnlyDeduced,
-                           unsigned Level,
-                           llvm::SmallBitVector &Deduced);
-
 /// \brief If this is a non-static member function,
 static void
 AddImplicitObjectParameterType(ASTContext &Context,
diff --git a/lib/Sema/SemaTemplateInstantiate.cpp b/lib/Sema/SemaTemplateInstantiate.cpp
index 160c9f090788..ba4a5b7bc0d7 100644
--- a/lib/Sema/SemaTemplateInstantiate.cpp
+++ b/lib/Sema/SemaTemplateInstantiate.cpp
@@ -2280,16 +2280,18 @@ namespace {
   };
 }
 
-bool Sema::InstantiateClassTemplateSpecialization(
-    SourceLocation PointOfInstantiation,
+/// Get the instantiation pattern to use to instantiate the definition of a
+/// given ClassTemplateSpecializationDecl (either the pattern of the primary
+/// template or of a partial specialization).
+static CXXRecordDecl *
+getPatternForClassTemplateSpecialization(
+    Sema &S, SourceLocation PointOfInstantiation,
     ClassTemplateSpecializationDecl *ClassTemplateSpec,
     TemplateSpecializationKind TSK, bool Complain) {
-  // Perform the actual instantiation on the canonical declaration.
-  ClassTemplateSpec = cast<ClassTemplateSpecializationDecl>(
-                                         ClassTemplateSpec->getCanonicalDecl());
-  if (ClassTemplateSpec->isInvalidDecl())
-    return true;
-  
+  Sema::InstantiatingTemplate Inst(S, PointOfInstantiation, ClassTemplateSpec);
+  if (Inst.isInvalid() || Inst.isAlreadyInstantiating())
+    return nullptr;
+
   ClassTemplateDecl *Template = ClassTemplateSpec->getSpecializedTemplate();
   CXXRecordDecl *Pattern = nullptr;
 
@@ -2309,15 +2311,13 @@ bool Sema::InstantiateClassTemplateSpecialization(
   for (unsigned I = 0, N = PartialSpecs.size(); I != N; ++I) {
     ClassTemplatePartialSpecializationDecl *Partial = PartialSpecs[I];
     TemplateDeductionInfo Info(FailedCandidates.getLocation());
-    if (TemplateDeductionResult Result
-          = DeduceTemplateArguments(Partial,
-                                    ClassTemplateSpec->getTemplateArgs(),
-                                    Info)) {
+    if (Sema::TemplateDeductionResult Result = S.DeduceTemplateArguments(
+            Partial, ClassTemplateSpec->getTemplateArgs(), Info)) {
       // Store the failed-deduction information for use in diagnostics, later.
       // TODO: Actually use the failed-deduction info?
       FailedCandidates.addCandidate().set(
           DeclAccessPair::make(Template, AS_public), Partial,
-          MakeDeductionFailureInfo(Context, Result, Info));
+          MakeDeductionFailureInfo(S.Context, Result, Info));
       (void)Result;
     } else {
       Matched.push_back(PartialSpecMatchResult());
@@ -2347,9 +2347,8 @@ bool Sema::InstantiateClassTemplateSpecialization(
       for (SmallVectorImpl<MatchResult>::iterator P = Best + 1,
                                                PEnd = Matched.end();
            P != PEnd; ++P) {
-        if (getMoreSpecializedPartialSpecialization(P->Partial, Best->Partial,
-                                                    PointOfInstantiation) 
-              == P->Partial)
+        if (S.getMoreSpecializedPartialSpecialization(
+                P->Partial, Best->Partial, PointOfInstantiation) == P->Partial)
           Best = P;
       }
       
@@ -2360,9 +2359,9 @@ bool Sema::InstantiateClassTemplateSpecialization(
                                                PEnd = Matched.end();
            P != PEnd; ++P) {
         if (P != Best &&
-            getMoreSpecializedPartialSpecialization(P->Partial, Best->Partial,
-                                                    PointOfInstantiation)
-              != Best->Partial) {
+            S.getMoreSpecializedPartialSpecialization(P->Partial, Best->Partial,
+                                                      PointOfInstantiation) !=
+                Best->Partial) {
           Ambiguous = true;
           break;
         }
@@ -2370,20 +2369,20 @@ bool Sema::InstantiateClassTemplateSpecialization(
        
       if (Ambiguous) {
         // Partial ordering did not produce a clear winner. Complain.
+        Inst.Clear();
         ClassTemplateSpec->setInvalidDecl();
-        Diag(PointOfInstantiation, diag::err_partial_spec_ordering_ambiguous)
+        S.Diag(PointOfInstantiation, diag::err_partial_spec_ordering_ambiguous)
           << ClassTemplateSpec;
         
         // Print the matching partial specializations.
         for (SmallVectorImpl<MatchResult>::iterator P = Matched.begin(),
                                                  PEnd = Matched.end();
              P != PEnd; ++P)
-          Diag(P->Partial->getLocation(), diag::note_partial_spec_match)
-            << getTemplateArgumentBindingsText(
-                                            P->Partial->getTemplateParameters(),
-                                               *P->Args);
+          S.Diag(P->Partial->getLocation(), diag::note_partial_spec_match)
+            << S.getTemplateArgumentBindingsText(
+                   P->Partial->getTemplateParameters(), *P->Args);
 
-        return true;
+        return nullptr;
       }
     }
     
@@ -2416,13 +2415,27 @@ bool Sema::InstantiateClassTemplateSpecialization(
     Pattern = OrigTemplate->getTemplatedDecl();
   }
 
-  bool Result = InstantiateClass(PointOfInstantiation, ClassTemplateSpec, 
-                                 Pattern,
-                                getTemplateInstantiationArgs(ClassTemplateSpec),
-                                 TSK,
-                                 Complain);
+  return Pattern;
+}
 
-  return Result;
+bool Sema::InstantiateClassTemplateSpecialization(
+    SourceLocation PointOfInstantiation,
+    ClassTemplateSpecializationDecl *ClassTemplateSpec,
+    TemplateSpecializationKind TSK, bool Complain) {
+  // Perform the actual instantiation on the canonical declaration.
+  ClassTemplateSpec = cast<ClassTemplateSpecializationDecl>(
+      ClassTemplateSpec->getCanonicalDecl());
+  if (ClassTemplateSpec->isInvalidDecl())
+    return true;
+
+  CXXRecordDecl *Pattern = getPatternForClassTemplateSpecialization(
+      *this, PointOfInstantiation, ClassTemplateSpec, TSK, Complain);
+  if (!Pattern)
+    return true;
+
+  return InstantiateClass(PointOfInstantiation, ClassTemplateSpec, Pattern,
+                          getTemplateInstantiationArgs(ClassTemplateSpec), TSK,
+                          Complain);
 }
 
 /// \brief Instantiates the definitions of all of the member
diff --git a/lib/Sema/SemaTemplateInstantiateDecl.cpp b/lib/Sema/SemaTemplateInstantiateDecl.cpp
index f4013b820641..d2a5e5cb5312 100644
--- a/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -168,39 +168,59 @@ static void instantiateDependentAlignValueAttr(
                         Aligned->getSpellingListIndex());
 }
 
-static void instantiateDependentEnableIfAttr(
+static Expr *instantiateDependentFunctionAttrCondition(
     Sema &S, const MultiLevelTemplateArgumentList &TemplateArgs,
-    const EnableIfAttr *A, const Decl *Tmpl, Decl *New) {
+    const Attr *A, Expr *OldCond, const Decl *Tmpl, FunctionDecl *New) {
   Expr *Cond = nullptr;
   {
-    EnterExpressionEvaluationContext Unevaluated(S, Sema::Unevaluated);
-    ExprResult Result = S.SubstExpr(A->getCond(), TemplateArgs);
+    Sema::ContextRAII SwitchContext(S, New);
+    EnterExpressionEvaluationContext Unevaluated(S, Sema::ConstantEvaluated);
+    ExprResult Result = S.SubstExpr(OldCond, TemplateArgs);
     if (Result.isInvalid())
-      return;
+      return nullptr;
     Cond = Result.getAs<Expr>();
   }
   if (!Cond->isTypeDependent()) {
     ExprResult Converted = S.PerformContextuallyConvertToBool(Cond);
     if (Converted.isInvalid())
-      return;
+      return nullptr;
     Cond = Converted.get();
   }
 
   SmallVector<PartialDiagnosticAt, 8> Diags;
-  if (A->getCond()->isValueDependent() && !Cond->isValueDependent() &&
-      !Expr::isPotentialConstantExprUnevaluated(Cond, cast<FunctionDecl>(New),
-                                                Diags)) {
-    S.Diag(A->getLocation(), diag::err_enable_if_never_constant_expr);
-    for (int I = 0, N = Diags.size(); I != N; ++I)
-      S.Diag(Diags[I].first, Diags[I].second);
-    return;
+  if (OldCond->isValueDependent() && !Cond->isValueDependent() &&
+      !Expr::isPotentialConstantExprUnevaluated(Cond, New, Diags)) {
+    S.Diag(A->getLocation(), diag::err_attr_cond_never_constant_expr) << A;
+    for (const auto &P : Diags)
+      S.Diag(P.first, P.second);
+    return nullptr;
   }
+  return Cond;
+}
 
-  EnableIfAttr *EIA = new (S.getASTContext())
-                        EnableIfAttr(A->getLocation(), S.getASTContext(), Cond,
-                                     A->getMessage(),
-                                     A->getSpellingListIndex());
-  New->addAttr(EIA);
+static void instantiateDependentEnableIfAttr(
+    Sema &S, const MultiLevelTemplateArgumentList &TemplateArgs,
+    const EnableIfAttr *EIA, const Decl *Tmpl, FunctionDecl *New) {
+  Expr *Cond = instantiateDependentFunctionAttrCondition(
+      S, TemplateArgs, EIA, EIA->getCond(), Tmpl, New);
+
+  if (Cond)
+    New->addAttr(new (S.getASTContext()) EnableIfAttr(
+        EIA->getLocation(), S.getASTContext(), Cond, EIA->getMessage(),
+        EIA->getSpellingListIndex()));
+}
+
+static void instantiateDependentDiagnoseIfAttr(
+    Sema &S, const MultiLevelTemplateArgumentList &TemplateArgs,
+    const DiagnoseIfAttr *DIA, const Decl *Tmpl, FunctionDecl *New) {
+  Expr *Cond = instantiateDependentFunctionAttrCondition(
+      S, TemplateArgs, DIA, DIA->getCond(), Tmpl, New);
+
+  if (Cond)
+    New->addAttr(new (S.getASTContext()) DiagnoseIfAttr(
+        DIA->getLocation(), S.getASTContext(), Cond, DIA->getMessage(),
+        DIA->getDiagnosticType(), DIA->getArgDependent(), New,
+        DIA->getSpellingListIndex()));
 }
 
 // Constructs and adds to New a new instance of CUDALaunchBoundsAttr using
@@ -334,7 +354,13 @@ void Sema::InstantiateAttrs(const MultiLevelTemplateArgumentList &TemplateArgs,
 
     if (const auto *EnableIf = dyn_cast<EnableIfAttr>(TmplAttr)) {
       instantiateDependentEnableIfAttr(*this, TemplateArgs, EnableIf, Tmpl,
-                                       New);
+                                       cast<FunctionDecl>(New));
+      continue;
+    }
+
+    if (const auto *DiagnoseIf = dyn_cast<DiagnoseIfAttr>(TmplAttr)) {
+      instantiateDependentDiagnoseIfAttr(*this, TemplateArgs, DiagnoseIf, Tmpl,
+                                         cast<FunctionDecl>(New));
       continue;
     }
 
diff --git a/lib/Serialization/ASTWriter.cpp b/lib/Serialization/ASTWriter.cpp
index 2a5eda436f09..39e842db2baa 100644
--- a/lib/Serialization/ASTWriter.cpp
+++ b/lib/Serialization/ASTWriter.cpp
@@ -4654,17 +4654,6 @@ uint64_t ASTWriter::WriteASTCore(Sema &SemaRef, StringRef isysroot,
   // If we're emitting a module, write out the submodule information.  
   if (WritingModule)
     WriteSubmodules(WritingModule);
-  else if (!getLangOpts().CurrentModule.empty()) {
-    // If we're building a PCH in the implementation of a module, we may need
-    // the description of the current module.
-    //
-    // FIXME: We may need other modules that we did not load from an AST file,
-    // such as if a module declares a 'conflicts' on a different module.
-    Module *M = PP.getHeaderSearchInfo().getModuleMap().findModule(
-        getLangOpts().CurrentModule);
-    if (M && !M->IsFromModuleFile)
-      WriteSubmodules(M);
-  }
 
   Stream.EmitRecord(SPECIAL_TYPES, SpecialTypes);
 
diff --git a/lib/StaticAnalyzer/Checkers/CMakeLists.txt b/lib/StaticAnalyzer/Checkers/CMakeLists.txt
index 41415f0376c0..05505ec38600 100644
--- a/lib/StaticAnalyzer/Checkers/CMakeLists.txt
+++ b/lib/StaticAnalyzer/Checkers/CMakeLists.txt
@@ -39,6 +39,7 @@ add_clang_library(clangStaticAnalyzerCheckers
   GenericTaintChecker.cpp
   GTestChecker.cpp
   IdenticalExprChecker.cpp
+  IteratorPastEndChecker.cpp
   IvarInvalidationChecker.cpp
   LLVMConventionsChecker.cpp
   LocalizationChecker.cpp
diff --git a/lib/StaticAnalyzer/Checkers/IteratorPastEndChecker.cpp b/lib/StaticAnalyzer/Checkers/IteratorPastEndChecker.cpp
new file mode 100644
index 000000000000..531054aa7887
--- /dev/null
+++ b/lib/StaticAnalyzer/Checkers/IteratorPastEndChecker.cpp
@@ -0,0 +1,842 @@
+//===-- IteratorPastEndChecker.cpp --------------------------------*- C++ -*--//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Defines a checker for using iterators outside their range (past end). Usage
+// means here dereferencing, incrementing etc.
+//
+//===----------------------------------------------------------------------===//
+
+#include "ClangSACheckers.h"
+#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
+#include "clang/StaticAnalyzer/Core/Checker.h"
+#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
+#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
+
+#include <utility>
+
+using namespace clang;
+using namespace ento;
+
+namespace {
+struct IteratorPosition {
+private:
+  enum Kind { InRange, OutofRange } K;
+  IteratorPosition(Kind InK) : K(InK) {}
+
+public:
+  bool isInRange() const { return K == InRange; }
+  bool isOutofRange() const { return K == OutofRange; }
+
+  static IteratorPosition getInRange() { return IteratorPosition(InRange); }
+  static IteratorPosition getOutofRange() {
+    return IteratorPosition(OutofRange);
+  }
+
+  bool operator==(const IteratorPosition &X) const { return K == X.K; }
+  bool operator!=(const IteratorPosition &X) const { return K != X.K; }
+  void Profile(llvm::FoldingSetNodeID &ID) const { ID.AddInteger(K); }
+};
+
+typedef llvm::PointerUnion<const MemRegion *, SymbolRef> RegionOrSymbol;
+
+struct IteratorComparison {
+private:
+  RegionOrSymbol Left, Right;
+  bool Equality;
+
+public:
+  IteratorComparison(RegionOrSymbol L, RegionOrSymbol R, bool Eq)
+      : Left(L), Right(R), Equality(Eq) {}
+
+  RegionOrSymbol getLeft() const { return Left; }
+  RegionOrSymbol getRight() const { return Right; }
+  bool isEquality() const { return Equality; }
+  bool operator==(const IteratorComparison &X) const {
+    return Left == X.Left && Right == X.Right && Equality == X.Equality;
+  }
+  bool operator!=(const IteratorComparison &X) const {
+    return Left != X.Left || Right != X.Right || Equality != X.Equality;
+  }
+  void Profile(llvm::FoldingSetNodeID &ID) const { ID.AddInteger(Equality); }
+};
+
+class IteratorPastEndChecker
+    : public Checker<
+          check::PreCall, check::PostCall, check::PreStmt<CXXOperatorCallExpr>,
+          check::PostStmt<CXXConstructExpr>, check::PostStmt<DeclStmt>,
+          check::PostStmt<MaterializeTemporaryExpr>, check::BeginFunction,
+          check::DeadSymbols, eval::Assume, eval::Call> {
+  mutable IdentifierInfo *II_find = nullptr,
+                         *II_find_end = nullptr, *II_find_first_of = nullptr,
+                         *II_find_if = nullptr, *II_find_if_not = nullptr,
+                         *II_lower_bound = nullptr, *II_upper_bound = nullptr,
+                         *II_search = nullptr, *II_search_n = nullptr;
+
+  std::unique_ptr<BugType> PastEndBugType;
+
+  void handleComparison(CheckerContext &C, const SVal &RetVal, const SVal &LVal,
+                        const SVal &RVal, OverloadedOperatorKind Op) const;
+  void handleAccess(CheckerContext &C, const SVal &Val) const;
+  void handleDecrement(CheckerContext &C, const SVal &Val) const;
+  void handleEnd(CheckerContext &C, const SVal &RetVal) const;
+
+  bool evalFind(CheckerContext &C, const CallExpr *CE) const;
+  bool evalFindEnd(CheckerContext &C, const CallExpr *CE) const;
+  bool evalFindFirstOf(CheckerContext &C, const CallExpr *CE) const;
+  bool evalFindIf(CheckerContext &C, const CallExpr *CE) const;
+  bool evalFindIfNot(CheckerContext &C, const CallExpr *CE) const;
+  bool evalLowerBound(CheckerContext &C, const CallExpr *CE) const;
+  bool evalUpperBound(CheckerContext &C, const CallExpr *CE) const;
+  bool evalSearch(CheckerContext &C, const CallExpr *CE) const;
+  bool evalSearchN(CheckerContext &C, const CallExpr *CE) const;
+  void Find(CheckerContext &C, const CallExpr *CE) const;
+
+  void reportPastEndBug(const StringRef &Message, const SVal &Val,
+                        CheckerContext &C, ExplodedNode *ErrNode) const;
+  void initIdentifiers(ASTContext &Ctx) const;
+
+public:
+  IteratorPastEndChecker();
+
+  void checkPreCall(const CallEvent &Call, CheckerContext &C) const;
+  void checkPostCall(const CallEvent &Call, CheckerContext &C) const;
+  void checkPreStmt(const CXXOperatorCallExpr *COCE, CheckerContext &C) const;
+  void checkBeginFunction(CheckerContext &C) const;
+  void checkPostStmt(const CXXConstructExpr *CCE, CheckerContext &C) const;
+  void checkPostStmt(const DeclStmt *DS, CheckerContext &C) const;
+  void checkPostStmt(const MaterializeTemporaryExpr *MTE,
+                     CheckerContext &C) const;
+  void checkDeadSymbols(SymbolReaper &SR, CheckerContext &C) const;
+  ProgramStateRef evalAssume(ProgramStateRef State, SVal Cond,
+                             bool Assumption) const;
+  bool evalCall(const CallExpr *CE, CheckerContext &C) const;
+};
+}
+
+REGISTER_MAP_WITH_PROGRAMSTATE(IteratorSymbolMap, SymbolRef, IteratorPosition)
+REGISTER_MAP_WITH_PROGRAMSTATE(IteratorRegionMap, const MemRegion *,
+                               IteratorPosition)
+
+REGISTER_MAP_WITH_PROGRAMSTATE(IteratorComparisonMap, const SymExpr *,
+                               IteratorComparison)
+
+#define INIT_ID(Id)                                                            \
+  if (!II_##Id)                                                                \
+  II_##Id = &Ctx.Idents.get(#Id)
+
+namespace {
+
+bool isIteratorType(const QualType &Type);
+bool isIterator(const CXXRecordDecl *CRD);
+bool isEndCall(const FunctionDecl *Func);
+bool isSimpleComparisonOperator(OverloadedOperatorKind OK);
+bool isAccessOperator(OverloadedOperatorKind OK);
+bool isDecrementOperator(OverloadedOperatorKind OK);
+BinaryOperator::Opcode getOpcode(const SymExpr *SE);
+const RegionOrSymbol getRegionOrSymbol(const SVal &Val);
+const ProgramStateRef processComparison(ProgramStateRef State,
+                                        RegionOrSymbol LVal,
+                                        RegionOrSymbol RVal, bool Equal);
+const ProgramStateRef saveComparison(ProgramStateRef State,
+                                     const SymExpr *Condition, const SVal &LVal,
+                                     const SVal &RVal, bool Eq);
+const IteratorComparison *loadComparison(ProgramStateRef State,
+                                         const SymExpr *Condition);
+const IteratorPosition *getIteratorPosition(ProgramStateRef State,
+                                            const SVal &Val);
+const IteratorPosition *getIteratorPosition(ProgramStateRef State,
+                                            RegionOrSymbol RegOrSym);
+ProgramStateRef setIteratorPosition(ProgramStateRef State, const SVal &Val,
+                                    IteratorPosition Pos);
+ProgramStateRef setIteratorPosition(ProgramStateRef State,
+                                    RegionOrSymbol RegOrSym,
+                                    IteratorPosition Pos);
+ProgramStateRef adjustIteratorPosition(ProgramStateRef State,
+                                       RegionOrSymbol RegOrSym,
+                                       IteratorPosition Pos, bool Equal);
+bool contradictingIteratorPositions(IteratorPosition Pos1,
+                                    IteratorPosition Pos2, bool Equal);
+}
+
+IteratorPastEndChecker::IteratorPastEndChecker() {
+  PastEndBugType.reset(
+      new BugType(this, "Iterator Past End", "Misuse of STL APIs"));
+  PastEndBugType->setSuppressOnSink(true);
+}
+
+void IteratorPastEndChecker::checkPreCall(const CallEvent &Call,
+                                          CheckerContext &C) const {
+  // Check for access past end
+  const auto *Func = Call.getDecl()->getAsFunction();
+  if (!Func)
+    return;
+  if (Func->isOverloadedOperator()) {
+    if (isAccessOperator(Func->getOverloadedOperator())) {
+      if (const auto *InstCall = dyn_cast<CXXInstanceCall>(&Call)) {
+        handleAccess(C, InstCall->getCXXThisVal());
+      } else {
+        handleAccess(C, Call.getArgSVal(0));
+      }
+    }
+  }
+}
+
+void IteratorPastEndChecker::checkPostCall(const CallEvent &Call,
+                                           CheckerContext &C) const {
+  // Record end() iterators, iterator decrementation and comparison
+  const auto *Func = Call.getDecl()->getAsFunction();
+  if (!Func)
+    return;
+  if (Func->isOverloadedOperator()) {
+    const auto Op = Func->getOverloadedOperator();
+    if (isSimpleComparisonOperator(Op)) {
+      if (Func->isCXXInstanceMember()) {
+        const auto &InstCall = static_cast<const CXXInstanceCall &>(Call);
+        handleComparison(C, InstCall.getReturnValue(), InstCall.getCXXThisVal(),
+                         InstCall.getArgSVal(0), Op);
+      } else {
+        handleComparison(C, Call.getReturnValue(), Call.getArgSVal(0),
+                         Call.getArgSVal(1), Op);
+      }
+    } else if (isDecrementOperator(Func->getOverloadedOperator())) {
+      if (Func->isCXXInstanceMember()) {
+        const auto &InstCall = static_cast<const CXXInstanceCall &>(Call);
+        handleDecrement(C, InstCall.getCXXThisVal());
+      } else {
+        handleDecrement(C, Call.getArgSVal(0));
+      }
+    }
+  } else if (Func->isCXXInstanceMember()) {
+    if (!isEndCall(Func))
+      return;
+    if (!isIteratorType(Call.getResultType()))
+      return;
+    handleEnd(C, Call.getReturnValue());
+  }
+}
+
+void IteratorPastEndChecker::checkPreStmt(const CXXOperatorCallExpr *COCE,
+                                          CheckerContext &C) const {
+  const auto *ThisExpr = COCE->getArg(0);
+
+  auto State = C.getState();
+  const auto *LCtx = C.getPredecessor()->getLocationContext();
+
+  const auto CurrentThis = State->getSVal(ThisExpr, LCtx);
+  if (const auto *Reg = CurrentThis.getAsRegion()) {
+    if (!Reg->getAs<CXXTempObjectRegion>())
+      return;
+    const auto OldState = C.getPredecessor()->getFirstPred()->getState();
+    const auto OldThis = OldState->getSVal(ThisExpr, LCtx);
+    const auto *Pos = getIteratorPosition(OldState, OldThis);
+    if (!Pos)
+      return;
+    State = setIteratorPosition(State, CurrentThis, *Pos);
+    C.addTransition(State);
+  }
+}
+
+void IteratorPastEndChecker::checkBeginFunction(CheckerContext &C) const {
+  // Copy state of iterator arguments to iterator parameters
+  auto State = C.getState();
+  const auto *LCtx = C.getLocationContext();
+
+  const auto *Site = cast<StackFrameContext>(LCtx)->getCallSite();
+  if (!Site)
+    return;
+
+  const auto *FD = dyn_cast<FunctionDecl>(LCtx->getDecl());
+  if (!FD)
+    return;
+
+  const auto *CE = dyn_cast<CallExpr>(Site);
+  if (!CE)
+    return;
+
+  bool Change = false;
+  int idx = 0;
+  for (const auto P : FD->parameters()) {
+    auto Param = State->getLValue(P, LCtx);
+    auto Arg = State->getSVal(CE->getArg(idx++), LCtx->getParent());
+    const auto *Pos = getIteratorPosition(State, Arg);
+    if (!Pos)
+      continue;
+    State = setIteratorPosition(State, Param, *Pos);
+    Change = true;
+  }
+  if (Change) {
+    C.addTransition(State);
+  }
+}
+
+void IteratorPastEndChecker::checkPostStmt(const CXXConstructExpr *CCE,
+                                           CheckerContext &C) const {
+  // Transfer iterator state in case of copy or move by constructor
+  const auto *ctr = CCE->getConstructor();
+  if (!ctr->isCopyOrMoveConstructor())
+    return;
+  const auto *RHSExpr = CCE->getArg(0);
+
+  auto State = C.getState();
+  const auto *LCtx = C.getLocationContext();
+
+  const auto RetVal = State->getSVal(CCE, LCtx);
+
+  const auto RHSVal = State->getSVal(RHSExpr, LCtx);
+  const auto *RHSPos = getIteratorPosition(State, RHSVal);
+  if (!RHSPos)
+    return;
+  State = setIteratorPosition(State, RetVal, *RHSPos);
+  C.addTransition(State);
+}
+
+void IteratorPastEndChecker::checkPostStmt(const DeclStmt *DS,
+                                           CheckerContext &C) const {
+  // Transfer iterator state to new variable declaration
+  for (const auto *D : DS->decls()) {
+    const auto *VD = dyn_cast<VarDecl>(D);
+    if (!VD || !VD->hasInit())
+      continue;
+
+    auto State = C.getState();
+    const auto *LCtx = C.getPredecessor()->getLocationContext();
+    const auto *Pos =
+        getIteratorPosition(State, State->getSVal(VD->getInit(), LCtx));
+    if (!Pos)
+      continue;
+    State = setIteratorPosition(State, State->getLValue(VD, LCtx), *Pos);
+    C.addTransition(State);
+  }
+}
+
+void IteratorPastEndChecker::checkPostStmt(const MaterializeTemporaryExpr *MTE,
+                                           CheckerContext &C) const {
+  /* Transfer iterator state for to temporary objects */
+  auto State = C.getState();
+  const auto *LCtx = C.getPredecessor()->getLocationContext();
+  const auto *Pos =
+      getIteratorPosition(State, State->getSVal(MTE->GetTemporaryExpr(), LCtx));
+  if (!Pos)
+    return;
+  State = setIteratorPosition(State, State->getSVal(MTE, LCtx), *Pos);
+  C.addTransition(State);
+}
+
+void IteratorPastEndChecker::checkDeadSymbols(SymbolReaper &SR,
+                                              CheckerContext &C) const {
+  auto State = C.getState();
+
+  auto RegionMap = State->get<IteratorRegionMap>();
+  for (const auto Reg : RegionMap) {
+    if (!SR.isLiveRegion(Reg.first)) {
+      State = State->remove<IteratorRegionMap>(Reg.first);
+    }
+  }
+
+  auto SymbolMap = State->get<IteratorSymbolMap>();
+  for (const auto Sym : SymbolMap) {
+    if (SR.isDead(Sym.first)) {
+      State = State->remove<IteratorSymbolMap>(Sym.first);
+    }
+  }
+
+  auto ComparisonMap = State->get<IteratorComparisonMap>();
+  for (const auto Comp : ComparisonMap) {
+    if (SR.isDead(Comp.first)) {
+      State = State->remove<IteratorComparisonMap>(Comp.first);
+    }
+  }
+}
+
+ProgramStateRef IteratorPastEndChecker::evalAssume(ProgramStateRef State,
+                                                   SVal Cond,
+                                                   bool Assumption) const {
+  // Load recorded comparison and transfer iterator state between sides
+  // according to comparison operator and assumption
+  const auto *SE = Cond.getAsSymExpr();
+  if (!SE)
+    return State;
+
+  auto Opc = getOpcode(SE);
+  if (Opc != BO_EQ && Opc != BO_NE)
+    return State;
+
+  bool Negated = false;
+  const auto *Comp = loadComparison(State, SE);
+  if (!Comp) {
+    // Try negated comparison, which is a SymExpr to 0 integer comparison
+    const auto *SIE = dyn_cast<SymIntExpr>(SE);
+    if (!SIE)
+      return State;
+
+    if (SIE->getRHS() != 0)
+      return State;
+
+    SE = SIE->getLHS();
+    Negated = SIE->getOpcode() == BO_EQ; // Equal to zero means negation
+    Opc = getOpcode(SE);
+    if (Opc != BO_EQ && Opc != BO_NE)
+      return State;
+
+    Comp = loadComparison(State, SE);
+    if (!Comp)
+      return State;
+  }
+
+  return processComparison(State, Comp->getLeft(), Comp->getRight(),
+                           (Comp->isEquality() == Assumption) != Negated);
+}
+
+// FIXME: Evaluation of these STL calls should be moved to StdCLibraryFunctions
+//       checker (see patch r284960) or another similar checker for C++ STL
+//       functions (e.g. StdCXXLibraryFunctions or StdCppLibraryFunctions).
+bool IteratorPastEndChecker::evalCall(const CallExpr *CE,
+                                      CheckerContext &C) const {
+  const FunctionDecl *FD = C.getCalleeDecl(CE);
+  if (!FD)
+    return false;
+
+  ASTContext &Ctx = C.getASTContext();
+  initIdentifiers(Ctx);
+
+  if (FD->getKind() == Decl::Function) {
+    if (FD->isInStdNamespace()) {
+      if (FD->getIdentifier() == II_find) {
+        return evalFind(C, CE);
+      } else if (FD->getIdentifier() == II_find_end) {
+        return evalFindEnd(C, CE);
+      } else if (FD->getIdentifier() == II_find_first_of) {
+        return evalFindFirstOf(C, CE);
+      } else if (FD->getIdentifier() == II_find_if) {
+        return evalFindIf(C, CE);
+      } else if (FD->getIdentifier() == II_find_if) {
+        return evalFindIf(C, CE);
+      } else if (FD->getIdentifier() == II_find_if_not) {
+        return evalFindIfNot(C, CE);
+      } else if (FD->getIdentifier() == II_upper_bound) {
+        return evalUpperBound(C, CE);
+      } else if (FD->getIdentifier() == II_lower_bound) {
+        return evalLowerBound(C, CE);
+      } else if (FD->getIdentifier() == II_search) {
+        return evalSearch(C, CE);
+      } else if (FD->getIdentifier() == II_search_n) {
+        return evalSearchN(C, CE);
+      }
+    }
+  }
+
+  return false;
+}
+
+void IteratorPastEndChecker::handleComparison(CheckerContext &C,
+                                              const SVal &RetVal,
+                                              const SVal &LVal,
+                                              const SVal &RVal,
+                                              OverloadedOperatorKind Op) const {
+  // Record the operands and the operator of the comparison for the next
+  // evalAssume, if the result is a symbolic expression. If it is a concrete
+  // value (only one branch is possible), then transfer the state between
+  // the operands according to the operator and the result
+  auto State = C.getState();
+  if (const auto *Condition = RetVal.getAsSymbolicExpression()) {
+    const auto *LPos = getIteratorPosition(State, LVal);
+    const auto *RPos = getIteratorPosition(State, RVal);
+    if (!LPos && !RPos)
+      return;
+    State = saveComparison(State, Condition, LVal, RVal, Op == OO_EqualEqual);
+    C.addTransition(State);
+  } else if (const auto TruthVal = RetVal.getAs<nonloc::ConcreteInt>()) {
+    if ((State = processComparison(
+             State, getRegionOrSymbol(LVal), getRegionOrSymbol(RVal),
+             (Op == OO_EqualEqual) == (TruthVal->getValue() != 0)))) {
+      C.addTransition(State);
+    } else {
+      C.generateSink(State, C.getPredecessor());
+    }
+  }
+}
+
+void IteratorPastEndChecker::handleAccess(CheckerContext &C,
+                                          const SVal &Val) const {
+  auto State = C.getState();
+  const auto *Pos = getIteratorPosition(State, Val);
+  if (Pos && Pos->isOutofRange()) {
+    auto *N = C.generateNonFatalErrorNode(State);
+    if (!N) {
+      return;
+    }
+    reportPastEndBug("Iterator accessed past its end.", Val, C, N);
+  }
+}
+
+void IteratorPastEndChecker::handleDecrement(CheckerContext &C,
+                                             const SVal &Val) const {
+  auto State = C.getState();
+  const auto *Pos = getIteratorPosition(State, Val);
+  if (Pos && Pos->isOutofRange()) {
+    State = setIteratorPosition(State, Val, IteratorPosition::getInRange());
+    // FIXME: We could also check for iterators ahead of their beginnig in the
+    //       future, but currently we do not care for such errors. We also
+    //       assume that the iterator is not past its end by more then one
+    //       position.
+    C.addTransition(State);
+  }
+}
+
+void IteratorPastEndChecker::handleEnd(CheckerContext &C,
+                                       const SVal &RetVal) const {
+  auto State = C.getState();
+  State = setIteratorPosition(State, RetVal, IteratorPosition::getOutofRange());
+  C.addTransition(State);
+}
+
+bool IteratorPastEndChecker::evalFind(CheckerContext &C,
+                                      const CallExpr *CE) const {
+  if (CE->getNumArgs() == 3 && isIteratorType(CE->getArg(0)->getType()) &&
+      isIteratorType(CE->getArg(1)->getType())) {
+    Find(C, CE);
+    return true;
+  }
+  return false;
+}
+
+bool IteratorPastEndChecker::evalFindEnd(CheckerContext &C,
+                                         const CallExpr *CE) const {
+  if ((CE->getNumArgs() == 4 || CE->getNumArgs() == 5) &&
+      isIteratorType(CE->getArg(0)->getType()) &&
+      isIteratorType(CE->getArg(1)->getType()) &&
+      isIteratorType(CE->getArg(2)->getType()) &&
+      isIteratorType(CE->getArg(3)->getType())) {
+    Find(C, CE);
+    return true;
+  }
+  return false;
+}
+
+bool IteratorPastEndChecker::evalFindFirstOf(CheckerContext &C,
+                                             const CallExpr *CE) const {
+  if ((CE->getNumArgs() == 4 || CE->getNumArgs() == 5) &&
+      isIteratorType(CE->getArg(0)->getType()) &&
+      isIteratorType(CE->getArg(1)->getType()) &&
+      isIteratorType(CE->getArg(2)->getType()) &&
+      isIteratorType(CE->getArg(3)->getType())) {
+    Find(C, CE);
+    return true;
+  }
+  return false;
+}
+
+bool IteratorPastEndChecker::evalFindIf(CheckerContext &C,
+                                        const CallExpr *CE) const {
+  if (CE->getNumArgs() == 3 && isIteratorType(CE->getArg(0)->getType()) &&
+      isIteratorType(CE->getArg(1)->getType())) {
+    Find(C, CE);
+    return true;
+  }
+  return false;
+}
+
+bool IteratorPastEndChecker::evalFindIfNot(CheckerContext &C,
+                                           const CallExpr *CE) const {
+  if (CE->getNumArgs() == 3 && isIteratorType(CE->getArg(0)->getType()) &&
+      isIteratorType(CE->getArg(1)->getType())) {
+    Find(C, CE);
+    return true;
+  }
+  return false;
+}
+
+bool IteratorPastEndChecker::evalLowerBound(CheckerContext &C,
+                                            const CallExpr *CE) const {
+  if ((CE->getNumArgs() == 3 || CE->getNumArgs() == 4) &&
+      isIteratorType(CE->getArg(0)->getType()) &&
+      isIteratorType(CE->getArg(1)->getType())) {
+    Find(C, CE);
+    return true;
+  }
+  return false;
+}
+
+bool IteratorPastEndChecker::evalUpperBound(CheckerContext &C,
+                                            const CallExpr *CE) const {
+  if ((CE->getNumArgs() == 3 || CE->getNumArgs() == 4) &&
+      isIteratorType(CE->getArg(0)->getType()) &&
+      isIteratorType(CE->getArg(1)->getType())) {
+    Find(C, CE);
+    return true;
+  }
+  return false;
+}
+
+bool IteratorPastEndChecker::evalSearch(CheckerContext &C,
+                                        const CallExpr *CE) const {
+  if ((CE->getNumArgs() == 4 || CE->getNumArgs() == 5) &&
+      isIteratorType(CE->getArg(0)->getType()) &&
+      isIteratorType(CE->getArg(1)->getType()) &&
+      isIteratorType(CE->getArg(2)->getType()) &&
+      isIteratorType(CE->getArg(3)->getType())) {
+    Find(C, CE);
+    return true;
+  }
+  return false;
+}
+
+bool IteratorPastEndChecker::evalSearchN(CheckerContext &C,
+                                         const CallExpr *CE) const {
+  if ((CE->getNumArgs() == 4 || CE->getNumArgs() == 5) &&
+      isIteratorType(CE->getArg(0)->getType()) &&
+      isIteratorType(CE->getArg(1)->getType())) {
+    Find(C, CE);
+    return true;
+  }
+  return false;
+}
+
+void IteratorPastEndChecker::Find(CheckerContext &C, const CallExpr *CE) const {
+  auto state = C.getState();
+  auto &svalBuilder = C.getSValBuilder();
+  const auto *LCtx = C.getLocationContext();
+
+  auto RetVal = svalBuilder.conjureSymbolVal(nullptr, CE, LCtx, C.blockCount());
+  auto SecondParam = state->getSVal(CE->getArg(1), LCtx);
+
+  auto stateFound = state->BindExpr(CE, LCtx, RetVal);
+  auto stateNotFound = state->BindExpr(CE, LCtx, SecondParam);
+
+  C.addTransition(stateFound);
+  C.addTransition(stateNotFound);
+}
+
+void IteratorPastEndChecker::reportPastEndBug(const StringRef &Message,
+                                              const SVal &Val,
+                                              CheckerContext &C,
+                                              ExplodedNode *ErrNode) const {
+  auto R = llvm::make_unique<BugReport>(*PastEndBugType, Message, ErrNode);
+  R->markInteresting(Val);
+  C.emitReport(std::move(R));
+}
+
+void IteratorPastEndChecker::initIdentifiers(ASTContext &Ctx) const {
+  INIT_ID(find);
+  INIT_ID(find_end);
+  INIT_ID(find_first_of);
+  INIT_ID(find_if);
+  INIT_ID(find_if_not);
+  INIT_ID(lower_bound);
+  INIT_ID(upper_bound);
+  INIT_ID(search);
+  INIT_ID(search_n);
+}
+
+namespace {
+
+bool isIteratorType(const QualType &Type) {
+  if (Type->isPointerType())
+    return true;
+
+  const auto *CRD = Type->getUnqualifiedDesugaredType()->getAsCXXRecordDecl();
+  return isIterator(CRD);
+}
+
+bool isIterator(const CXXRecordDecl *CRD) {
+  if (!CRD)
+    return false;
+
+  const auto Name = CRD->getName();
+  if (!(Name.endswith_lower("iterator") || Name.endswith_lower("iter") ||
+        Name.endswith_lower("it")))
+    return false;
+
+  bool HasCopyCtor = false, HasCopyAssign = true, HasDtor = false,
+       HasPreIncrOp = false, HasPostIncrOp = false, HasDerefOp = false;
+  for (const auto *Method : CRD->methods()) {
+    if (const auto *Ctor = dyn_cast<CXXConstructorDecl>(Method)) {
+      if (Ctor->isCopyConstructor()) {
+        HasCopyCtor = !Ctor->isDeleted() && Ctor->getAccess() == AS_public;
+      }
+      continue;
+    }
+    if (const auto *Dtor = dyn_cast<CXXDestructorDecl>(Method)) {
+      HasDtor = !Dtor->isDeleted() && Dtor->getAccess() == AS_public;
+      continue;
+    }
+    if (Method->isCopyAssignmentOperator()) {
+      HasCopyAssign = !Method->isDeleted() && Method->getAccess() == AS_public;
+      continue;
+    }
+    if (!Method->isOverloadedOperator())
+      continue;
+    const auto OPK = Method->getOverloadedOperator();
+    if (OPK == OO_PlusPlus) {
+      HasPreIncrOp = HasPreIncrOp || (Method->getNumParams() == 0);
+      HasPostIncrOp = HasPostIncrOp || (Method->getNumParams() == 1);
+      continue;
+    }
+    if (OPK == OO_Star) {
+      HasDerefOp = (Method->getNumParams() == 0);
+      continue;
+    }
+  }
+
+  return HasCopyCtor && HasCopyAssign && HasDtor && HasPreIncrOp &&
+         HasPostIncrOp && HasDerefOp;
+}
+
+bool isEndCall(const FunctionDecl *Func) {
+  const auto *IdInfo = Func->getIdentifier();
+  if (!IdInfo)
+    return false;
+  return IdInfo->getName().endswith_lower("end");
+}
+
+bool isSimpleComparisonOperator(OverloadedOperatorKind OK) {
+  return OK == OO_EqualEqual || OK == OO_ExclaimEqual;
+}
+
+bool isAccessOperator(OverloadedOperatorKind OK) {
+  return OK == OO_Star || OK == OO_Arrow || OK == OO_ArrowStar ||
+         OK == OO_Plus || OK == OO_PlusEqual || OK == OO_PlusPlus ||
+         OK == OO_Subscript;
+}
+
+bool isDecrementOperator(OverloadedOperatorKind OK) {
+  return OK == OO_MinusEqual || OK == OO_MinusMinus;
+}
+
+BinaryOperator::Opcode getOpcode(const SymExpr *SE) {
+  if (const auto *BSE = dyn_cast<BinarySymExpr>(SE)) {
+    return BSE->getOpcode();
+  } else if (const auto *SC = dyn_cast<SymbolConjured>(SE)) {
+    const auto *COE = dyn_cast<CXXOperatorCallExpr>(SC->getStmt());
+    if (!COE)
+      return BO_Comma; // Extremal value, neither EQ nor NE
+    if (COE->getOperator() == OO_EqualEqual) {
+      return BO_EQ;
+    } else if (COE->getOperator() == OO_ExclaimEqual) {
+      return BO_NE;
+    }
+    return BO_Comma; // Extremal value, neither EQ nor NE
+  }
+  return BO_Comma; // Extremal value, neither EQ nor NE
+}
+
+const RegionOrSymbol getRegionOrSymbol(const SVal &Val) {
+  if (const auto Reg = Val.getAsRegion()) {
+    return Reg;
+  } else if (const auto Sym = Val.getAsSymbol()) {
+    return Sym;
+  } else if (const auto LCVal = Val.getAs<nonloc::LazyCompoundVal>()) {
+    return LCVal->getRegion();
+  }
+  return RegionOrSymbol();
+}
+
+const ProgramStateRef processComparison(ProgramStateRef State,
+                                        RegionOrSymbol LVal,
+                                        RegionOrSymbol RVal, bool Equal) {
+  const auto *LPos = getIteratorPosition(State, LVal);
+  const auto *RPos = getIteratorPosition(State, RVal);
+  if (LPos && !RPos) {
+    State = adjustIteratorPosition(State, RVal, *LPos, Equal);
+  } else if (!LPos && RPos) {
+    State = adjustIteratorPosition(State, LVal, *RPos, Equal);
+  } else if (LPos && RPos) {
+    if (contradictingIteratorPositions(*LPos, *RPos, Equal)) {
+      return nullptr;
+    }
+  }
+  return State;
+}
+
+const ProgramStateRef saveComparison(ProgramStateRef State,
+                                     const SymExpr *Condition, const SVal &LVal,
+                                     const SVal &RVal, bool Eq) {
+  const auto Left = getRegionOrSymbol(LVal);
+  const auto Right = getRegionOrSymbol(RVal);
+  if (!Left || !Right)
+    return State;
+  return State->set<IteratorComparisonMap>(Condition,
+                                           IteratorComparison(Left, Right, Eq));
+}
+
+const IteratorComparison *loadComparison(ProgramStateRef State,
+                                         const SymExpr *Condition) {
+  return State->get<IteratorComparisonMap>(Condition);
+}
+
+const IteratorPosition *getIteratorPosition(ProgramStateRef State,
+                                            const SVal &Val) {
+  if (const auto Reg = Val.getAsRegion()) {
+    return State->get<IteratorRegionMap>(Reg);
+  } else if (const auto Sym = Val.getAsSymbol()) {
+    return State->get<IteratorSymbolMap>(Sym);
+  } else if (const auto LCVal = Val.getAs<nonloc::LazyCompoundVal>()) {
+    return State->get<IteratorRegionMap>(LCVal->getRegion());
+  }
+  return nullptr;
+}
+
+const IteratorPosition *getIteratorPosition(ProgramStateRef State,
+                                            RegionOrSymbol RegOrSym) {
+  if (RegOrSym.is<const MemRegion *>()) {
+    return State->get<IteratorRegionMap>(RegOrSym.get<const MemRegion *>());
+  } else if (RegOrSym.is<SymbolRef>()) {
+    return State->get<IteratorSymbolMap>(RegOrSym.get<SymbolRef>());
+  }
+  return nullptr;
+}
+
+ProgramStateRef setIteratorPosition(ProgramStateRef State, const SVal &Val,
+                                    IteratorPosition Pos) {
+  if (const auto Reg = Val.getAsRegion()) {
+    return State->set<IteratorRegionMap>(Reg, Pos);
+  } else if (const auto Sym = Val.getAsSymbol()) {
+    return State->set<IteratorSymbolMap>(Sym, Pos);
+  } else if (const auto LCVal = Val.getAs<nonloc::LazyCompoundVal>()) {
+    return State->set<IteratorRegionMap>(LCVal->getRegion(), Pos);
+  }
+  return nullptr;
+}
+
+ProgramStateRef setIteratorPosition(ProgramStateRef State,
+                                    RegionOrSymbol RegOrSym,
+                                    IteratorPosition Pos) {
+  if (RegOrSym.is<const MemRegion *>()) {
+    return State->set<IteratorRegionMap>(RegOrSym.get<const MemRegion *>(),
+                                         Pos);
+  } else if (RegOrSym.is<SymbolRef>()) {
+    return State->set<IteratorSymbolMap>(RegOrSym.get<SymbolRef>(), Pos);
+  }
+  return nullptr;
+}
+
+ProgramStateRef adjustIteratorPosition(ProgramStateRef State,
+                                       RegionOrSymbol RegOrSym,
+                                       IteratorPosition Pos, bool Equal) {
+
+  if ((Pos.isInRange() && Equal) || (Pos.isOutofRange() && !Equal)) {
+    return setIteratorPosition(State, RegOrSym, IteratorPosition::getInRange());
+  } else if (Pos.isOutofRange() && Equal) {
+    return setIteratorPosition(State, RegOrSym,
+                               IteratorPosition::getOutofRange());
+  } else {
+    return State;
+  }
+}
+
+bool contradictingIteratorPositions(IteratorPosition Pos1,
+                                    IteratorPosition Pos2, bool Equal) {
+  return ((Pos1 != Pos2) && Equal) ||
+         ((Pos1.isOutofRange() && Pos2.isOutofRange()) && !Equal);
+}
+}
+
+void ento::registerIteratorPastEndChecker(CheckerManager &Mgr) {
+  Mgr.registerChecker<IteratorPastEndChecker>();
+}
diff --git a/lib/StaticAnalyzer/Core/ExprEngine.cpp b/lib/StaticAnalyzer/Core/ExprEngine.cpp
index 707168b4de0a..7e7e329dc4d7 100644
--- a/lib/StaticAnalyzer/Core/ExprEngine.cpp
+++ b/lib/StaticAnalyzer/Core/ExprEngine.cpp
@@ -1248,7 +1248,14 @@ void ExprEngine::Visit(const Stmt *S, ExplodedNode *Pred,
     case Expr::MaterializeTemporaryExprClass: {
       Bldr.takeNodes(Pred);
       const MaterializeTemporaryExpr *MTE = cast<MaterializeTemporaryExpr>(S);
-      CreateCXXTemporaryObject(MTE, Pred, Dst);
+      ExplodedNodeSet dstPrevisit;
+      getCheckerManager().runCheckersForPreStmt(dstPrevisit, Pred, MTE, *this);
+      ExplodedNodeSet dstExpr;
+      for (ExplodedNodeSet::iterator i = dstPrevisit.begin(),
+                                     e = dstPrevisit.end(); i != e ; ++i) {
+        CreateCXXTemporaryObject(MTE, *i, dstExpr);
+      }
+      getCheckerManager().runCheckersForPostStmt(Dst, dstExpr, MTE, *this);
       Bldr.addNodes(Dst);
       break;
     }