6 files changed, 21 insertions, 5 deletions
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index 30d35f61c22..7671ab3f3a1 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -5012,7 +5012,7 @@ public:
                                          SourceLocation RBrac,
                                          AttributeList *AttrList);
   void ActOnFinishCXXMemberDecls();
-  void ActOnFinishCXXMethodDefs(Decl *D);
+  void ActOnFinishCXXMemberDefaultArgs(Decl *D);
 
   void ActOnReenterCXXMethodParameter(Scope *S, ParmVarDecl *Param);
   unsigned ActOnReenterTemplateScope(Scope *S, Decl *Template);
diff --git a/clang/lib/CodeGen/MicrosoftCXXABI.cpp b/clang/lib/CodeGen/MicrosoftCXXABI.cpp
index 6417b87444d..b09d658c820 100644
--- a/clang/lib/CodeGen/MicrosoftCXXABI.cpp
+++ b/clang/lib/CodeGen/MicrosoftCXXABI.cpp
@@ -3411,8 +3411,11 @@ MicrosoftCXXABI::getAddrOfCXXCtorClosure(const CXXConstructorDecl *CD,
 
   // Add the rest of the default arguments.
   std::vector<Stmt *> ArgVec;
-  for (unsigned I = IsCopy ? 1 : 0, E = CD->getNumParams(); I != E; ++I)
-    ArgVec.push_back(getContext().getDefaultArgExprForConstructor(CD, I));
+  for (unsigned I = IsCopy ? 1 : 0, E = CD->getNumParams(); I != E; ++I) {
+    Stmt *DefaultArg = getContext().getDefaultArgExprForConstructor(CD, I);
+    assert(DefaultArg && "sema forgot to instantiate default args");
+    ArgVec.push_back(DefaultArg);
+  }
 
   CodeGenFunction::RunCleanupsScope Cleanups(CGF);
 
diff --git a/clang/lib/Parse/ParseDeclCXX.cpp b/clang/lib/Parse/ParseDeclCXX.cpp
index d5497085f2d..c5655941187 100644
--- a/clang/lib/Parse/ParseDeclCXX.cpp
+++ b/clang/lib/Parse/ParseDeclCXX.cpp
@@ -2918,7 +2918,7 @@ void Parser::ParseCXXMemberSpecification(SourceLocation RecordLoc,
 
     // We've finished parsing everything, including default argument
     // initializers.
-    Actions.ActOnFinishCXXMethodDefs(TagDecl);
+    Actions.ActOnFinishCXXMemberDefaultArgs(TagDecl);
   }
 
   if (TagDecl)
diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index 4e64595e114..f7183bc2c4a 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -9449,7 +9449,7 @@ static void getDefaultArgExprsForConstructors(Sema &S, CXXRecordDecl *Class) {
   }
 }
 
-void Sema::ActOnFinishCXXMethodDefs(Decl *D) {
+void Sema::ActOnFinishCXXMemberDefaultArgs(Decl *D) {
   auto *RD = dyn_cast<CXXRecordDecl>(D);
 
   // Default constructors that are annotated with __declspec(dllexport) which
diff --git a/clang/lib/Sema/SemaTemplateInstantiate.cpp b/clang/lib/Sema/SemaTemplateInstantiate.cpp
index 8ea1e6be911..8e4fe85077f 100644
--- a/clang/lib/Sema/SemaTemplateInstantiate.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiate.cpp
@@ -2043,6 +2043,10 @@ Sema::InstantiateClass(SourceLocation PointOfInstantiation,
               SourceLocation(), SourceLocation(), nullptr);
   CheckCompletedCXXClass(Instantiation);
 
+  // Default arguments are parsed, if not instantiated. We can go instantiate
+  // default arg exprs for default constructors if necessary now.
+  ActOnFinishCXXMemberDefaultArgs(Instantiation);
+
   // Instantiate late parsed attributes, and attach them to their decls.
   // See Sema::InstantiateAttrs
   for (LateInstantiatedAttrVec::iterator I = LateAttrs.begin(),
diff --git a/clang/test/CodeGenCXX/dllexport.cpp b/clang/test/CodeGenCXX/dllexport.cpp
index c71ab5c67d2..c6ab232a760 100644
--- a/clang/test/CodeGenCXX/dllexport.cpp
+++ b/clang/test/CodeGenCXX/dllexport.cpp
@@ -523,6 +523,15 @@ struct __declspec(dllexport) NestedOuter {
 // M32-DAG: define weak_odr dllexport x86_thiscallcc void @"\01??_FNestedOuter@@QAEXXZ"
 // M32-DAG: define weak_odr dllexport x86_thiscallcc void @"\01??_FNestedInner@NestedOuter@@QAEXXZ"
 
+template <typename T>
+struct SomeTemplate {
+  SomeTemplate(T o = T()) : o(o) {}
+  T o;
+};
+struct __declspec(dllexport) InheritFromTemplate : SomeTemplate<int> {};
+
+// M32-DAG: define weak_odr dllexport x86_thiscallcc void @"\01??_F?$SomeTemplate@H@@QAEXXZ"
+
 struct __declspec(dllexport) T {
   // Copy assignment operator:
   // M32-DAG: define weak_odr dllexport x86_thiscallcc dereferenceable({{[0-9]+}}) %struct.T* @"\01??4T@@QAEAAU0@ABU0@@Z"