From b77cc7f4eb3d35189e8cd904eafe9d0fc817dcfc Mon Sep 17 00:00:00 2001
From: Richard Smith <richard-llvm@metafoo.co.uk>
Date: Mon, 11 May 2015 23:09:06 +0000
Subject: [PATCH] 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.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@237064 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Parse/ParseTemplate.cpp                   |  4 +++-
 lib/Sema/SemaTemplateInstantiateDecl.cpp      |  8 ++++++++
 test/SemaTemplate/instantiate-local-class.cpp | 15 +++++++++++++++
 3 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/lib/Parse/ParseTemplate.cpp b/lib/Parse/ParseTemplate.cpp
index 53de72cd3c..f1467fe553 100644
--- a/lib/Parse/ParseTemplate.cpp
+++ b/lib/Parse/ParseTemplate.cpp
@@ -14,6 +14,7 @@
 #include "clang/Parse/Parser.h"
 #include "RAIIObjectsForParser.h"
 #include "clang/AST/ASTConsumer.h"
+#include "clang/AST/ASTContext.h"
 #include "clang/AST/DeclTemplate.h"
 #include "clang/Parse/ParseDiagnostic.h"
 #include "clang/Sema/DeclSpec.h"
@@ -1301,7 +1302,8 @@ void Parser::ParseLateTemplatedFuncDef(LateParsedTemplate &LPT) {
   TemplateParameterDepthRAII CurTemplateDepthTracker(TemplateParameterDepth);
 
   // To restore the context after late parsing.
-  Sema::ContextRAII GlobalSavedContext(Actions, Actions.CurContext);
+  Sema::ContextRAII GlobalSavedContext(
+      Actions, Actions.Context.getTranslationUnitDecl());
 
   SmallVector<ParseScope*, 4> TemplateParamScopeStack;
 
diff --git a/lib/Sema/SemaTemplateInstantiateDecl.cpp b/lib/Sema/SemaTemplateInstantiateDecl.cpp
index a0e8c2373d..4a92efdaae 100644
--- a/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/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);
diff --git a/test/SemaTemplate/instantiate-local-class.cpp b/test/SemaTemplate/instantiate-local-class.cpp
index 3365c37407..ff6cf7923f 100644
--- a/test/SemaTemplate/instantiate-local-class.cpp
+++ b/test/SemaTemplate/instantiate-local-class.cpp
@@ -1,4 +1,6 @@
 // RUN: %clang_cc1 -verify -std=c++11 %s
+// RUN: %clang_cc1 -verify -std=c++11 -fdelayed-template-parsing %s
+
 template<typename T>
 void f0() {
   struct X;
@@ -342,3 +344,16 @@ namespace PR18653 {
   };
   template struct S06<int>;
 }
+
+namespace PR20625 {
+template <typename T>
+void f() {
+  struct N {
+    static constexpr int get() { return 42; }
+  };
+  constexpr int n = N::get();
+  static_assert(n == 42, "n == 42");
+}
+
+void g() { f<void>(); }
+}
-- 
2.50.1