From 457e2815d43fa68f7ff7cd2f7e9d1bf7b6fdc653 Mon Sep 17 00:00:00 2001
From: Douglas Gregor <dgregor@apple.com>
Date: Wed, 28 Oct 2009 16:31:34 +0000
Subject: [PATCH] Mangle based on the declaration we're given, not the
 canonical declaration, since attributes that affect mangling may have been
 added to subsequent declarations. However, to determine the linkage of the
 declaration, we need to look at the canonical declaration. Fixes PR4412.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@85400 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/clang/AST/Redeclarable.h |  5 +++++
 lib/CodeGen/Mangle.cpp           |  3 ++-
 test/CodeGen/mangle.c            | 23 +++++++++++++++--------
 3 files changed, 22 insertions(+), 9 deletions(-)

diff --git a/include/clang/AST/Redeclarable.h b/include/clang/AST/Redeclarable.h
index 458af1f144..1e6871ff3b 100644
--- a/include/clang/AST/Redeclarable.h
+++ b/include/clang/AST/Redeclarable.h
@@ -88,6 +88,11 @@ public:
     return D;
   }
 
+  /// \brief Returns the most recent (re)declaration of this declaration.
+  const decl_type *getMostRecentDeclaration() const {
+    return getFirstDeclaration()->RedeclLink.getNext();
+  }
+  
   /// \brief Set the previous declaration. If PrevDecl is NULL, set this as the
   /// first and only declaration.
   void setPreviousDeclaration(decl_type *PrevDecl) {
diff --git a/lib/CodeGen/Mangle.cpp b/lib/CodeGen/Mangle.cpp
index b0015956be..40c11a5744 100644
--- a/lib/CodeGen/Mangle.cpp
+++ b/lib/CodeGen/Mangle.cpp
@@ -115,6 +115,7 @@ namespace {
 }
 
 static bool isInCLinkageSpecification(const Decl *D) {
+  D = D->getCanonicalDecl();
   for (const DeclContext *DC = D->getDeclContext();
        !DC->isTranslationUnit(); DC = DC->getParent()) {
     if (const LinkageSpecDecl *Linkage = dyn_cast<LinkageSpecDecl>(DC))
@@ -1362,7 +1363,7 @@ namespace clang {
                                    "Mangling declaration");
     
     CXXNameMangler Mangler(Context, os);
-    if (!Mangler.mangle(cast<NamedDecl>(D->getCanonicalDecl())))
+    if (!Mangler.mangle(D))
       return false;
 
     os.flush();
diff --git a/test/CodeGen/mangle.c b/test/CodeGen/mangle.c
index 17d74ba71f..6f42f6f649 100644
--- a/test/CodeGen/mangle.c
+++ b/test/CodeGen/mangle.c
@@ -1,22 +1,20 @@
-// RUN: clang-cc -triple i386-pc-linux-gnu -emit-llvm -o %t %s &&
-// RUN: grep '@_Z2f0i' %t &&
-// RUN: grep '@_Z2f0l' %t &&
+// RUN: clang-cc -triple i386-pc-linux-gnu -emit-llvm -o - %s | FileCheck %s
 
-// Make sure we mangle overloadable, even in C system headers.
+// CHECK: @"\01foo"
 
+// Make sure we mangle overloadable, even in C system headers.
 # 1 "somesystemheader.h" 1 3 4
+// CHECK: @_Z2f0i
 void __attribute__((__overloadable__)) f0(int a) {}
+// CHECK: @_Z2f0l
 void __attribute__((__overloadable__)) f0(long b) {}
 
-
+// CHECK: @"\01bar"
 
 // These should get merged.
 void foo() __asm__("bar");
 void foo2() __asm__("bar");
 
-// RUN: grep '@"\\01foo"' %t &&
-// RUN: grep '@"\\01bar"' %t
-
 int nux __asm__("foo");
 extern float nux2 __asm__("foo");
 
@@ -52,3 +50,12 @@ void foo6() {
 
 int foo7 __asm__("foo7") __attribute__((used));
 float foo8 __asm__("foo7") = 42;
+
+// PR4412
+int func(void);
+extern int func (void) __asm__ ("FUNC");
+
+// CHECK: @"\01FUNC"
+int func(void) {
+  return 42;
+}
-- 
2.40.0