From 8f77453f7cdee7de088e14aa9782b1ff30aa9bf7 Mon Sep 17 00:00:00 2001
From: David Majnemer <david.majnemer@gmail.com>
Date: Tue, 4 Mar 2014 05:38:05 +0000
Subject: [PATCH] MS ABI: Mangle variable templates properly

We wouldn't recognize variable templates as being templates leading us
to leave the template arguments off of the mangled name.  This would
allow two unrelated templates to map to the same mangled name.

N.B.  While MSVC doesn't support variable templates as of this date,
this mangling is the most likely thing they will choose to use.  Their
demangler can successfully demangle our manglings with the template
arguments shown.

llvm-svn: 202789
---
 clang/lib/AST/MicrosoftMangle.cpp         | 8 +++++++-
 clang/test/CodeGenCXX/mangle-ms-cxx14.cpp | 8 ++++++++
 2 files changed, 15 insertions(+), 1 deletion(-)
 create mode 100644 clang/test/CodeGenCXX/mangle-ms-cxx14.cpp

diff --git a/clang/lib/AST/MicrosoftMangle.cpp b/clang/lib/AST/MicrosoftMangle.cpp
index 72ab3732e2d7..a610e157d906 100644
--- a/clang/lib/AST/MicrosoftMangle.cpp
+++ b/clang/lib/AST/MicrosoftMangle.cpp
@@ -562,6 +562,13 @@ isTemplate(const NamedDecl *ND, const TemplateArgumentList *&TemplateArgs) {
     return Spec->getSpecializedTemplate();
   }
 
+  // Check if we have a variable template.
+  if (const VarTemplateSpecializationDecl *Spec =
+          dyn_cast<VarTemplateSpecializationDecl>(ND)) {
+    TemplateArgs = &Spec->getTemplateArgs();
+    return Spec->getSpecializedTemplate();
+  }
+
   return 0;
 }
 
@@ -585,7 +592,6 @@ MicrosoftCXXNameMangler::mangleUnqualifiedName(const NamedDecl *ND,
       return;
     }
 
-    // We have a class template.
     // Here comes the tricky thing: if we need to mangle something like
     //   void foo(A::X<Y>, B::X<Y>),
     // the X<Y> part is aliased. However, if you need to mangle
diff --git a/clang/test/CodeGenCXX/mangle-ms-cxx14.cpp b/clang/test/CodeGenCXX/mangle-ms-cxx14.cpp
new file mode 100644
index 000000000000..5bf0e967a79c
--- /dev/null
+++ b/clang/test/CodeGenCXX/mangle-ms-cxx14.cpp
@@ -0,0 +1,8 @@
+// RUN: %clang_cc1 -std=c++1y -fms-extensions -emit-llvm %s -o - -triple=i386-pc-win32 | FileCheck %s
+
+template <typename> int x = 0;
+
+// CHECK: "\01??$x@X@@3HA"
+template <> int x<void>;
+// CHECK: "\01??$x@H@@3HA"
+template <> int x<int>;