1 files changed, 51 insertions, 3 deletions

diff --git a/clang/lib/Sema/SemaTemplate.cpp b/clang/lib/Sema/SemaTemplate.cpp
index ad4ea2d2593d..4f577a3cf748 100644
--- a/clang/lib/Sema/SemaTemplate.cpp
+++ b/clang/lib/Sema/SemaTemplate.cpp
@@ -46,6 +46,48 @@ clang::getTemplateParamsRange(TemplateParameterList const * const *Ps,
   return SourceRange(Ps[0]->getTemplateLoc(), Ps[N-1]->getRAngleLoc());
 }
 
+unsigned Sema::getTemplateDepth(Scope *S) const {
+  unsigned Depth = 0;
+
+  // Each template parameter scope represents one level of template parameter
+  // depth.
+  for (Scope *TempParamScope = S->getTemplateParamParent();
+       TempParamScope && !Depth;
+       TempParamScope = TempParamScope->getParent()->getTemplateParamParent()) {
+    ++Depth;
+  }
+
+  // Note that there are template parameters with the given depth.
+  auto ParamsAtDepth = [&](unsigned D) { Depth = std::max(Depth, D + 1); };
+
+  // Look for parameters of an enclosing generic lambda. We don't create a
+  // template parameter scope for these.
+  for (FunctionScopeInfo *FSI : getFunctionScopes()) {
+    if (auto *LSI = dyn_cast<LambdaScopeInfo>(FSI)) {
+      if (!LSI->TemplateParams.empty()) {
+        ParamsAtDepth(LSI->AutoTemplateParameterDepth);
+        break;
+      }
+      if (LSI->GLTemplateParameterList) {
+        ParamsAtDepth(LSI->GLTemplateParameterList->getDepth());
+        break;
+      }
+    }
+  }
+
+  // Look for parameters of an enclosing terse function template. We don't
+  // create a template parameter scope for these either.
+  for (const InventedTemplateParameterInfo &Info :
+       getInventedParameterInfos()) {
+    if (!Info.TemplateParams.empty()) {
+      ParamsAtDepth(Info.AutoTemplateParameterDepth);
+      break;
+    }
+  }
+
+  return Depth;
+}
+
 /// \brief Determine whether the declaration found is acceptable as the name
 /// of a template and, if so, return that template declaration. Otherwise,
 /// returns null.
@@ -2173,9 +2215,15 @@ private:
     // constructor.
     ExprResult NewDefArg;
     if (OldParam->hasDefaultArg()) {
-      NewDefArg = SemaRef.SubstExpr(OldParam->getDefaultArg(), Args);
-      if (NewDefArg.isInvalid())
-        return nullptr;
+      // We don't care what the value is (we won't use it); just create a
+      // placeholder to indicate there is a default argument.
+      QualType ParamTy = NewDI->getType();
+      NewDefArg = new (SemaRef.Context)
+          OpaqueValueExpr(OldParam->getDefaultArg()->getBeginLoc(),
+                          ParamTy.getNonLValueExprType(SemaRef.Context),
+                          ParamTy->isLValueReferenceType() ? VK_LValue :
+                          ParamTy->isRValueReferenceType() ? VK_XValue :
+                          VK_RValue);
     }
 
     ParmVarDecl *NewParam = ParmVarDecl::Create(SemaRef.Context, DC,