2 files changed, 8 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;
 
diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
index b69cb5d8433..d31b48c122f 100644
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -4255,6 +4255,9 @@ static void handleGNUInlineAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
     return;
   }
 
+  if (S.LangOpts.CPlusPlus && Fn->getStorageClass() != SC_Extern)
+    S.Diag(AL.getLoc(), diag::warn_gnu_inline_cplusplus_without_extern);
+
   D->addAttr(::new (S.Context) GNUInlineAttr(S.Context, AL));
 }