merge hasCLanguageLinkage and isExternC. Keep the shorter name.

I added hasCLanguageLinkage while fixing some language linkage bugs some
time ago so that I wouldn't have to check all users of isExternC. It turned
out to be a much longer detour than expected, but this patch finally
merges the two again. The isExternC function now implements just the
standard notion of having C language linkage.

llvm-svn: 175119

1 files changed, 22 insertions, 20 deletions

diff --git a/clang/lib/AST/ItaniumMangle.cpp b/clang/lib/AST/ItaniumMangle.cpp
index a7fc16aae36..e9a3b034836 100644
--- a/clang/lib/AST/ItaniumMangle.cpp
+++ b/clang/lib/AST/ItaniumMangle.cpp
@@ -366,20 +366,34 @@ bool ItaniumMangleContext::shouldMangleDeclName(const NamedDecl *D) {
   if (D->hasAttr<AsmLabelAttr>())
     return true;
 
-  // Clang's "overloadable" attribute extension to C/C++ implies name mangling
-  // (always) as does passing a C++ member function and a function
-  // whose name is not a simple identifier.
   const FunctionDecl *FD = dyn_cast<FunctionDecl>(D);
-  if (FD && (FD->hasAttr<OverloadableAttr>() || isa<CXXMethodDecl>(FD) ||
-             !FD->getDeclName().isIdentifier()))
-    return true;
+  if (FD) {
+    LanguageLinkage L = FD->getLanguageLinkage();
+    // Overloadable functions need mangling.
+    if (FD->hasAttr<OverloadableAttr>())
+      return true;
+
+    // C functions and "main" are not mangled.
+    if (FD->isMain() || L == CLanguageLinkage)
+      return false;
+
+    // C++ functions and those whose names are not a simple identifier need
+    // mangling.
+    if (!FD->getDeclName().isIdentifier() || L == CXXLanguageLinkage)
+      return true;
+  }
 
   // Otherwise, no mangling is done outside C++ mode.
   if (!getASTContext().getLangOpts().CPlusPlus)
     return false;
 
-  // Variables at global scope with non-internal linkage are not mangled
-  if (!FD) {
+  const VarDecl *VD = dyn_cast<VarDecl>(D);
+  if (VD) {
+    // C variables are not mangled.
+    if (VD->isExternC())
+      return false;
+
+    // Variables at global scope with non-internal linkage are not mangled
     const DeclContext *DC = getEffectiveDeclContext(D);
     // Check for extern variable declared locally.
     if (DC->isFunctionOrMethod() && D->hasLinkage())
@@ -389,18 +403,6 @@ bool ItaniumMangleContext::shouldMangleDeclName(const NamedDecl *D) {
       return false;
   }
 
-  // Class members are always mangled.
-  if (getEffectiveDeclContext(D)->isRecord())
-    return true;
-
-  // C functions and "main" are not mangled.
-  if (FD)
-    return !FD->isMain() && !FD->hasCLanguageLinkage();
-
-  // C variables are not mangled.
-  if (const VarDecl *VD = dyn_cast<VarDecl>(D))
-    return !VD->hasCLanguageLinkage();
-
   return true;
 }