[PATCH] Disabling of "redefine_extname" pragma for C++ code

[Andrey Bokhanko]

Hi aaron.ballman, rsmith,

In response to Richard Smith's comment (http://lists.cs.uiuc.edu/pipermail/cfe-commits/Week-of-Mon-20150622/131782.html), this patch disables "redefine_extname" pragma for C++ code. Also, I added a test that this pragma doesn't apply to static declarations.

http://reviews.llvm.org/D10805

Files:
  lib/Sema/SemaDecl.cpp
  test/CodeGen/redefine_extname.c
  test/CodeGenCXX/redefine_extname.cpp

Index: test/CodeGenCXX/redefine_extname.cpp
===================================================================
--- test/CodeGenCXX/redefine_extname.cpp
+++ test/CodeGenCXX/redefine_extname.cpp
@@ -28,3 +28,9 @@
 // CHECK: define i32 @bar()
 }
 
+// Check that pragma redefine_extname applies to C code only, and shouldn't be
+// applied to C++.
+#pragma redefine_extname foo_cpp bar_cpp
+extern int foo_cpp() { return 1; }
+// CHECK-NOT: define i32 @bar_cpp()
+
Index: test/CodeGen/redefine_extname.c
===================================================================
--- test/CodeGen/redefine_extname.c
+++ test/CodeGen/redefine_extname.c
@@ -24,3 +24,9 @@
 extern int foo() { return 1; }
 // CHECK: define i32 @bar()
 
+// Check that pragma redefine_extname applies to external declarations only.
+#pragma redefine_extname foo_static bar_static
+static int foo_static() { return 1; }
+int baz() { return foo_static(); }
+// CHECK-NOT: call i32 @bar_static()
+
Index: lib/Sema/SemaDecl.cpp
===================================================================
--- lib/Sema/SemaDecl.cpp
+++ lib/Sema/SemaDecl.cpp
@@ -5525,15 +5525,16 @@
   return true;
 }
 
-/// \brief Returns true if given declaration is TU-scoped and externally
-/// visible.
-static bool isDeclTUScopedExternallyVisible(const Decl *D) {
+/// \brief Returns true if given declaration has external C language linkage.
+static bool isDeclExternC(const Decl *D) {
   if (auto *FD = dyn_cast<FunctionDecl>(D))
-    return (FD->getDeclContext()->isTranslationUnit() || FD->isExternC()) &&
-           FD->hasExternalFormalLinkage();
+  {
+    return FD->isExternC();
+  }
   else if (auto *VD = dyn_cast<VarDecl>(D))
-    return (VD->getDeclContext()->isTranslationUnit() || VD->isExternC()) &&
-           VD->hasExternalFormalLinkage();
+  {
+    return VD->isExternC();
+  }
 
   llvm_unreachable("Unknown type of decl!");
 }
@@ -5963,7 +5964,7 @@
     NewVD->addAttr(::new (Context) AsmLabelAttr(SE->getStrTokenLoc(0),
                                                 Context, Label, 0));
   } else if (!ExtnameUndeclaredIdentifiers.empty() &&
-             isDeclTUScopedExternallyVisible(NewVD)) {
+             isDeclExternC(NewVD)) {
     llvm::DenseMap<IdentifierInfo*,AsmLabelAttr*>::iterator I =
       ExtnameUndeclaredIdentifiers.find(NewVD->getIdentifier());
     if (I != ExtnameUndeclaredIdentifiers.end()) {
@@ -7491,7 +7492,7 @@
     NewFD->addAttr(::new (Context) AsmLabelAttr(SE->getStrTokenLoc(0), Context,
                                                 SE->getString(), 0));
   } else if (!ExtnameUndeclaredIdentifiers.empty() &&
-             isDeclTUScopedExternallyVisible(NewFD)) {
+             isDeclExternC(NewFD)) {
     llvm::DenseMap<IdentifierInfo*,AsmLabelAttr*>::iterator I =
       ExtnameUndeclaredIdentifiers.find(NewFD->getIdentifier());
     if (I != ExtnameUndeclaredIdentifiers.end()) {
@@ -14284,7 +14285,7 @@
   // already exists, add a label attribute to it.
   if (PrevDecl &&
       (isa<FunctionDecl>(PrevDecl) || isa<VarDecl>(PrevDecl)) &&
-      PrevDecl->hasExternalFormalLinkage())
+      isDeclExternC(PrevDecl))
     PrevDecl->addAttr(Attr);
   // Otherwise, add a label atttibute to ExtnameUndeclaredIdentifiers.
   else

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