1 files changed, 29 insertions, 26 deletions

diff --git a/lib/AST/Decl.cpp b/lib/AST/Decl.cpp
index 094e8dcff0886..0f2558e24ba56 100644
--- a/lib/AST/Decl.cpp
+++ b/lib/AST/Decl.cpp
@@ -2251,6 +2251,14 @@ bool VarDecl::checkInitIsICE() const {
   return Eval->IsICE;
 }
 
+template<typename DeclT>
+static DeclT *getDefinitionOrSelf(DeclT *D) {
+  assert(D);
+  if (auto *Def = D->getDefinition())
+    return Def;
+  return D;
+}
+
 VarDecl *VarDecl::getTemplateInstantiationPattern() const {
   // If it's a variable template specialization, find the template or partial
   // specialization from which it was instantiated.
@@ -2262,7 +2270,7 @@ VarDecl *VarDecl::getTemplateInstantiationPattern() const {
           break;
         VTD = NewVTD;
       }
-      return VTD->getTemplatedDecl()->getDefinition();
+      return getDefinitionOrSelf(VTD->getTemplatedDecl());
     }
     if (auto *VTPSD =
             From.dyn_cast<VarTemplatePartialSpecializationDecl *>()) {
@@ -2271,7 +2279,7 @@ VarDecl *VarDecl::getTemplateInstantiationPattern() const {
           break;
         VTPSD = NewVTPSD;
       }
-      return VTPSD->getDefinition();
+      return getDefinitionOrSelf<VarDecl>(VTPSD);
     }
   }
 
@@ -2280,23 +2288,18 @@ VarDecl *VarDecl::getTemplateInstantiationPattern() const {
       VarDecl *VD = getInstantiatedFromStaticDataMember();
       while (auto *NewVD = VD->getInstantiatedFromStaticDataMember())
         VD = NewVD;
-      return VD->getDefinition();
+      return getDefinitionOrSelf(VD);
     }
   }
 
   if (VarTemplateDecl *VarTemplate = getDescribedVarTemplate()) {
-
     while (VarTemplate->getInstantiatedFromMemberTemplate()) {
       if (VarTemplate->isMemberSpecialization())
         break;
       VarTemplate = VarTemplate->getInstantiatedFromMemberTemplate();
     }
 
-    assert((!VarTemplate->getTemplatedDecl() ||
-            !isTemplateInstantiation(getTemplateSpecializationKind())) &&
-           "couldn't find pattern for variable instantiation");
-
-    return VarTemplate->getTemplatedDecl();
+    return getDefinitionOrSelf(VarTemplate->getTemplatedDecl());
   }
   return nullptr;
 }
@@ -3198,9 +3201,12 @@ bool FunctionDecl::isTemplateInstantiation() const {
    
 FunctionDecl *FunctionDecl::getTemplateInstantiationPattern() const {
   // Handle class scope explicit specialization special case.
-  if (getTemplateSpecializationKind() == TSK_ExplicitSpecialization)
-    return getClassScopeSpecializationPattern();
-  
+  if (getTemplateSpecializationKind() == TSK_ExplicitSpecialization) {
+    if (auto *Spec = getClassScopeSpecializationPattern())
+      return getDefinitionOrSelf(Spec);
+    return nullptr;
+  }
+
   // If this is a generic lambda call operator specialization, its 
   // instantiation pattern is always its primary template's pattern
   // even if its primary template was instantiated from another 
@@ -3212,16 +3218,10 @@ FunctionDecl *FunctionDecl::getTemplateInstantiationPattern() const {
 
   if (isGenericLambdaCallOperatorSpecialization(
           dyn_cast<CXXMethodDecl>(this))) {
-    assert(getPrimaryTemplate() && "A generic lambda specialization must be "
-                                   "generated from a primary call operator "
-                                   "template");
-    assert(getPrimaryTemplate()->getTemplatedDecl()->getBody() &&
-           "A generic lambda call operator template must always have a body - "
-           "even if instantiated from a prototype (i.e. as written) member "
-           "template");
-    return getPrimaryTemplate()->getTemplatedDecl();
+    assert(getPrimaryTemplate() && "not a generic lambda call operator?");
+    return getDefinitionOrSelf(getPrimaryTemplate()->getTemplatedDecl());
   }
-  
+
   if (FunctionTemplateDecl *Primary = getPrimaryTemplate()) {
     while (Primary->getInstantiatedFromMemberTemplate()) {
       // If we have hit a point where the user provided a specialization of
@@ -3230,11 +3230,14 @@ FunctionDecl *FunctionDecl::getTemplateInstantiationPattern() const {
         break;
       Primary = Primary->getInstantiatedFromMemberTemplate();
     }
-    
-    return Primary->getTemplatedDecl();
+
+    return getDefinitionOrSelf(Primary->getTemplatedDecl());
   } 
-    
-  return getInstantiatedFromMemberFunction();
+
+  if (auto *MFD = getInstantiatedFromMemberFunction())
+    return getDefinitionOrSelf(MFD);
+
+  return nullptr;
 }
 
 FunctionTemplateDecl *FunctionDecl::getPrimaryTemplate() const {
@@ -3778,7 +3781,7 @@ EnumDecl *EnumDecl::getTemplateInstantiationPattern() const {
       EnumDecl *ED = getInstantiatedFromMemberEnum();
       while (auto *NewED = ED->getInstantiatedFromMemberEnum())
         ED = NewED;
-      return ED;
+      return getDefinitionOrSelf(ED);
     }
   }