Fix a bug in the mangler where in 'namespace std { extern "C" {X;} }', X would not be seen to be in ::std::.

Migrate two other places where the same logic is used to use the helper function that already exists.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@152022 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/AST/ItaniumMangle.cpp b/lib/AST/ItaniumMangle.cpp
index 48e2a62..b7b0443 100644
--- a/lib/AST/ItaniumMangle.cpp
+++ b/lib/AST/ItaniumMangle.cpp
@@ -553,8 +553,7 @@
     return;
   }
 
-  while (isa<LinkageSpecDecl>(DC))
-    DC = getEffectiveParentContext(DC);
+  DC = IgnoreLinkageSpecDecls(DC);
 
   if (DC->isTranslationUnit() || isStdNamespace(DC)) {
     // Check if we have a template.
@@ -594,7 +593,8 @@
 void CXXNameMangler::mangleUnscopedName(const NamedDecl *ND) {
   //  <unscoped-name> ::= <unqualified-name>
   //                  ::= St <unqualified-name>   # ::std::
-  if (isStdNamespace(getEffectiveDeclContext(ND)))
+
+  if (isStdNamespace(IgnoreLinkageSpecDecls(getEffectiveDeclContext(ND))))
     Out << "St";
 
   mangleUnqualifiedName(ND);
@@ -1393,8 +1393,7 @@
   //           ::= # empty
   //           ::= <substitution>
 
-  while (isa<LinkageSpecDecl>(DC))
-    DC = getEffectiveParentContext(DC);
+  DC = IgnoreLinkageSpecDecls(DC);
 
   if (DC->isTranslationUnit())
     return;
diff --git a/test/CodeGenCXX/mangle-std-externc.cpp b/test/CodeGenCXX/mangle-std-externc.cpp
new file mode 100644
index 0000000..a478dee
--- /dev/null
+++ b/test/CodeGenCXX/mangle-std-externc.cpp
@@ -0,0 +1,27 @@
+// RUN: %clang_cc1 %s -DNS=std -emit-llvm -o - | FileCheck %s --check-prefix=CHECK-STD
+// RUN: %clang_cc1 %s -DNS=n -emit-llvm -o - | FileCheck %s --check-prefix=CHECK-N
+
+// _ZNSt1DISt1CE1iE = std::D<std::C>::i
+// CHECK-STD: @_ZNSt1DISt1CE1iE = 
+
+// _ZN1n1DINS_1CEE1iE == n::D<n::C>::i
+// CHECK-N: @_ZN1n1DINS_1CEE1iE = 
+
+namespace NS {
+  extern "C" {
+    class C {
+    };
+  }
+
+  template <class T>
+  class D {
+  public:
+    static int i;
+  };
+
+}
+
+
+int f() {
+  return NS::D<NS::C>::i;
+}