Itanium ABI: Template template parameters are usable as substitutions

Template template parameters weren't added to the list of substitutions.
This would make the substitution map contain inaccurate mappings,
leading to Clang violating the Itanium ABI and breaking compatibility
with GCC.

This fixes PR21351.

Differential Revision: http://reviews.llvm.org/D5959

llvm-svn: 220588

2 files changed, 29 insertions, 10 deletions

diff --git a/clang/lib/AST/ItaniumMangle.cpp b/clang/lib/AST/ItaniumMangle.cpp
index 5965ef05158..76664673d53 100644
--- a/clang/lib/AST/ItaniumMangle.cpp
+++ b/clang/lib/AST/ItaniumMangle.cpp
@@ -637,13 +637,11 @@ void CXXNameMangler::mangleUnscopedTemplateName(const TemplateDecl *ND) {
     return;
 
   // <template-template-param> ::= <template-param>
-  if (const TemplateTemplateParmDecl *TTP
-                                     = dyn_cast<TemplateTemplateParmDecl>(ND)) {
+  if (const auto *TTP = dyn_cast<TemplateTemplateParmDecl>(ND))
     mangleTemplateParameter(TTP->getIndex());
-    return;
-  }
+  else
+    mangleUnscopedName(ND->getTemplatedDecl());
 
-  mangleUnscopedName(ND->getTemplatedDecl());
   addSubstitution(ND);
 }
 
@@ -1563,14 +1561,13 @@ void CXXNameMangler::mangleTemplatePrefix(const TemplateDecl *ND,
     return;
 
   // <template-template-param> ::= <template-param>
-  if (const TemplateTemplateParmDecl *TTP
-                                     = dyn_cast<TemplateTemplateParmDecl>(ND)) {
+  if (const auto *TTP = dyn_cast<TemplateTemplateParmDecl>(ND)) {
     mangleTemplateParameter(TTP->getIndex());
-    return;
+  } else {
+    manglePrefix(getEffectiveDeclContext(ND), NoFunction);
+    mangleUnqualifiedName(ND->getTemplatedDecl());
   }
 
-  manglePrefix(getEffectiveDeclContext(ND), NoFunction);
-  mangleUnqualifiedName(ND->getTemplatedDecl());
   addSubstitution(ND);
 }
 
diff --git a/clang/test/CodeGenCXX/mangle.cpp b/clang/test/CodeGenCXX/mangle.cpp
index 9bdac7f1728..9af0d9da997 100644
--- a/clang/test/CodeGenCXX/mangle.cpp
+++ b/clang/test/CodeGenCXX/mangle.cpp
@@ -991,3 +991,25 @@ namespace test48 {
   template void f<S>(S::u *);
   // CHECK-LABEL: define weak_odr void @_ZN6test481fINS_1SEEEvPTuNT_1uE(%"union.test48::S::u"*)
 }
+
+namespace test49 {
+  template <int>
+  struct S {};
+
+  template <template <int> class T>
+  T<3> fin(T<3>);
+
+  auto v = fin<S>;
+  // CHECK-LABEL: declare void @_ZN6test493finINS_1SEEET_ILi3EES3_()
+}
+
+namespace test50 {
+  template <int>
+  struct S {};
+
+  template <template <int> class T>
+  T<3> fin(T<4>);
+
+  auto v = fin<S>;
+  // CHECK-LABEL: declare void @_ZN6test503finINS_1SEEET_ILi3EES2_ILi4EE()
+}