PR20625: Instantiate static constexpr member function of a local struct in a function template earlier.

This is necessary in order to allow the use of a constexpr member function, or
a member function with deduced return type, of a local class within a
surrounding instantiated function template specialization.

Patch by Michael Park!

This re-commits r236063, which was reverted in r236134, along with a fix for a
delayed template parsing bug that was exposed by this change.

llvm-svn: 237064

1 files changed, 8 insertions, 0 deletions

diff --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
index a0e8c2373da..4a92efdaae2 100644
--- a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -1302,11 +1302,19 @@ Decl *TemplateDeclInstantiator::VisitCXXRecordDecl(CXXRecordDecl *D) {
   // DR1484 clarifies that the members of a local class are instantiated as part
   // of the instantiation of their enclosing entity.
   if (D->isCompleteDefinition() && D->isLocalClass()) {
+    Sema::SavePendingLocalImplicitInstantiationsRAII
+        SavedPendingLocalImplicitInstantiations(SemaRef);
+
     SemaRef.InstantiateClass(D->getLocation(), Record, D, TemplateArgs,
                              TSK_ImplicitInstantiation,
                              /*Complain=*/true);
+
     SemaRef.InstantiateClassMembers(D->getLocation(), Record, TemplateArgs,
                                     TSK_ImplicitInstantiation);
+
+    // This class may have local implicit instantiations that need to be
+    // performed within this scope.
+    SemaRef.PerformPendingInstantiations(/*LocalOnly=*/true);
   }
 
   SemaRef.DiagnoseUnusedNestedTypedefs(Record);