Mangle extern "C" functions whose names are not simple identifiers.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@175166 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/AST/ItaniumMangle.cpp b/lib/AST/ItaniumMangle.cpp
index 1f95a2f..d427b08 100644
--- a/lib/AST/ItaniumMangle.cpp
+++ b/lib/AST/ItaniumMangle.cpp
@@ -373,8 +373,8 @@
     if (FD->hasAttr<OverloadableAttr>())
       return true;
 
-    // C functions and "main" are not mangled.
-    if (FD->isMain() || L == CLanguageLinkage)
+    // "main" is not mangled.
+    if (FD->isMain())
       return false;
 
     // C++ functions and those whose names are not a simple identifier need
@@ -382,6 +382,10 @@
     if (!FD->getDeclName().isIdentifier() || L == CXXLanguageLinkage)
       return true;
 
+    // C functions are not mangled.
+    if (L == CLanguageLinkage)
+      return false;
+
     // FIXME: Users assume they know the mangling of static functions
     // declared in extern "C" contexts, so we cannot always mangle them.
     // As an improvement, maybe we could mangle them only if they are actually