[clang] [AST] Treat "inline gnu_inline" the same way as "extern inline gnu_inline" in C++ mode

This matches how GCC handles it, see e.g. https://gcc.godbolt.org/z/HPplnl.
GCC documents the gnu_inline attribute with "In C++, this attribute does
not depend on extern in any way, but it still requires the inline keyword
to enable its special behavior."

The previous behaviour of gnu_inline in C++, without the extern
keyword, can be traced back to the original commit that added
support for gnu_inline, SVN r69045.

Differential Revision: https://reviews.llvm.org/D67414

llvm-svn: 373078

1 files changed, 5 insertions, 3 deletions

diff --git a/clang/lib/AST/Decl.cpp b/clang/lib/AST/Decl.cpp
index e95338138fe..19a012b332d 100644
--- a/clang/lib/AST/Decl.cpp
+++ b/clang/lib/AST/Decl.cpp
@@ -3261,6 +3261,9 @@ bool FunctionDecl::doesDeclarationForceExternallyVisibleDefinition() const {
       return true;
   }
 
+  if (Context.getLangOpts().CPlusPlus)
+    return false;
+
   if (Context.getLangOpts().GNUInline || hasAttr<GNUInlineAttr>()) {
     // With GNU inlining, a declaration with 'inline' but not 'extern', forces
     // an externally visible definition.
@@ -3289,9 +3292,6 @@ bool FunctionDecl::doesDeclarationForceExternallyVisibleDefinition() const {
     return FoundBody;
   }
 
-  if (Context.getLangOpts().CPlusPlus)
-    return false;
-
   // C99 6.7.4p6:
   //   [...] If all of the file scope declarations for a function in a
   //   translation unit include the inline function specifier without extern,
@@ -3371,6 +3371,8 @@ bool FunctionDecl::isInlineDefinitionExternallyVisible() const {
     // If it's not the case that both 'inline' and 'extern' are
     // specified on the definition, then this inline definition is
     // externally visible.
+    if (Context.getLangOpts().CPlusPlus)
+      return false;
     if (!(isInlineSpecified() && getStorageClass() == SC_Extern))
       return true;