From 234ff47366f6ae6acdd22b7b83ce91044561da60 Mon Sep 17 00:00:00 2001
From: Richard Smith <richard-llvm@metafoo.co.uk>
Date: Sat, 23 Aug 2014 00:49:01 +0000
Subject: [PATCH] [modules] Put class template declarations into the scope in
 which they're declared, rather than putting them into the template parameter
 scope. We previously had *no record* in the scope for class template
 declarations, once those declarations completed and their template parameter
 scopes were popped. This in turn caused us to be unable to merge class
 template declarations that were declared in the global scope (where we use
 scope lookup rather than DeclContext lookup for merging), when loading a
 module.

llvm-svn: 216311
---
 clang/lib/Sema/SemaTemplate.cpp                  | 10 +++++++---
 clang/test/Modules/Inputs/cxx-templates-common.h |  2 ++
 .../test/Modules/Inputs/cxx-templates-textual.h  |  2 ++
 clang/test/Modules/cxx-templates.cpp             | 16 ++++++++++++++++
 4 files changed, 27 insertions(+), 3 deletions(-)
 create mode 100644 clang/test/Modules/Inputs/cxx-templates-textual.h

diff --git a/clang/lib/Sema/SemaTemplate.cpp b/clang/lib/Sema/SemaTemplate.cpp
index 63581a44dbe5..fb05718ff1b5 100644
--- a/clang/lib/Sema/SemaTemplate.cpp
+++ b/clang/lib/Sema/SemaTemplate.cpp
@@ -1105,9 +1105,13 @@ Sema::CheckClassTemplate(Scope *S, unsigned TagSpec, TagUseKind TUK,
 
   AddPushedVisibilityAttribute(NewClass);
 
-  if (TUK != TUK_Friend)
-    PushOnScopeChains(NewTemplate, S);
-  else {
+  if (TUK != TUK_Friend) {
+    // Per C++ [basic.scope.temp]p2, skip the template parameter scopes.
+    Scope *Outer = S;
+    while ((Outer->getFlags() & Scope::TemplateParamScope) != 0)
+      Outer = Outer->getParent();
+    PushOnScopeChains(NewTemplate, Outer);
+  } else {
     if (PrevClassTemplate && PrevClassTemplate->getAccess() != AS_none) {
       NewTemplate->setAccess(PrevClassTemplate->getAccess());
       NewClass->setAccess(PrevClassTemplate->getAccess());
diff --git a/clang/test/Modules/Inputs/cxx-templates-common.h b/clang/test/Modules/Inputs/cxx-templates-common.h
index f7c083249f8a..f3c902230911 100644
--- a/clang/test/Modules/Inputs/cxx-templates-common.h
+++ b/clang/test/Modules/Inputs/cxx-templates-common.h
@@ -40,3 +40,5 @@ template<typename T> struct WithExplicitSpecialization;
 typedef WithExplicitSpecialization<int> WithExplicitSpecializationUse;
 
 template<typename T> struct WithImplicitSpecialMembers { int n; };
+
+#include "cxx-templates-textual.h"
diff --git a/clang/test/Modules/Inputs/cxx-templates-textual.h b/clang/test/Modules/Inputs/cxx-templates-textual.h
new file mode 100644
index 000000000000..8bffb8eddc28
--- /dev/null
+++ b/clang/test/Modules/Inputs/cxx-templates-textual.h
@@ -0,0 +1,2 @@
+template<typename T> struct MergeClassTemplateSpecializations_basic_string {};
+typedef MergeClassTemplateSpecializations_basic_string<char> MergeClassTemplateSpecializations_string;
diff --git a/clang/test/Modules/cxx-templates.cpp b/clang/test/Modules/cxx-templates.cpp
index c173d670802f..fedaa03ef4fc 100644
--- a/clang/test/Modules/cxx-templates.cpp
+++ b/clang/test/Modules/cxx-templates.cpp
@@ -3,6 +3,11 @@
 // RUN: not %clang_cc1 -x objective-c++ -fmodules -fno-modules-error-recovery -fmodules-cache-path=%t -I %S/Inputs %s -std=c++11 -ast-dump-lookups -ast-dump-filter N | FileCheck %s --check-prefix=CHECK-NAMESPACE-N
 // RUN: not %clang_cc1 -x objective-c++ -fmodules -fno-modules-error-recovery -fmodules-cache-path=%t -I %S/Inputs %s -std=c++11 -ast-dump | FileCheck %s --check-prefix=CHECK-DUMP
 // RUN: %clang_cc1 -x objective-c++ -fmodules -fno-modules-error-recovery -fmodules-cache-path=%t -I %S/Inputs %s -verify -std=c++11
+// RUN: %clang_cc1 -x objective-c++ -fmodules -fno-modules-error-recovery -fmodules-cache-path=%t -I %S/Inputs %s -verify -std=c++11 -DEARLY_IMPORT
+
+#ifdef EARLY_IMPORT
+#include "cxx-templates-textual.h"
+#endif
 
 @import cxx_templates_a;
 @import cxx_templates_b;
@@ -22,8 +27,14 @@ void g() {
   f<double>(1.0);
   f<int>();
   f(); // expected-error {{no matching function}}
+#ifdef EARLY_IMPORT
+  // FIXME: The textual inclusion above shouldn't affect this!
+  // expected-note@Inputs/cxx-templates-a.h:3 {{couldn't infer template argument}}
+  // expected-note@Inputs/cxx-templates-a.h:4 {{requires 1 argument}}
+#else
   // expected-note@Inputs/cxx-templates-b.h:3 {{couldn't infer template argument}}
   // expected-note@Inputs/cxx-templates-b.h:4 {{requires single argument}}
+#endif
 
   N::f(0);
   N::f<double>(1.0);
@@ -108,11 +119,15 @@ void g() {
   int *r = PartiallyInstantiatePartialSpec<int*>::bar();
 
   (void)&WithImplicitSpecialMembers<int>::n;
+
+  MergeClassTemplateSpecializations_string s;
 }
 
 static_assert(Outer<int>::Inner<int>::f() == 1, "");
 static_assert(Outer<int>::Inner<int>::g() == 2, "");
 
+#ifndef EARLY_IMPORT
+// FIXME: The textual inclusion above shouldn't cause this to fail!
 static_assert(MergeTemplateDefinitions<int>::f() == 1, "");
 static_assert(MergeTemplateDefinitions<int>::g() == 2, "");
 
@@ -126,6 +141,7 @@ MergeSpecializations<int[]>::partially_specialized_in_c spec_in_c_1;
 MergeSpecializations<char>::explicitly_specialized_in_a spec_in_a_2;
 MergeSpecializations<double>::explicitly_specialized_in_b spec_in_b_2;
 MergeSpecializations<bool>::explicitly_specialized_in_c spec_in_c_2;
+#endif
 
 @import cxx_templates_common;