4 files changed, 26 insertions, 16 deletions
diff --git a/include/clang/Basic/DiagnosticSemaKinds.td b/include/clang/Basic/DiagnosticSemaKinds.td
index 4507b2fd57..a07f00697b 100644
--- a/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/include/clang/Basic/DiagnosticSemaKinds.td
@@ -2997,11 +2997,14 @@ def warn_undefined_internal : Warning<
 def note_used_here : Note<"used here">;
 
 def warn_internal_in_extern_inline : ExtWarn<
-  "%select{function|variable}0 %1 %select{has internal linkage|is in an anonymous"
-  " namespace}2 but is used in an inline %select{function|method}3 with"
-  " external linkage">,
+  "%select{function|variable}0 %1 has internal linkage but is used in an "
+  "inline function with external linkage">,
   InGroup<DiagGroup<"internal-linkage-in-inline"> >;
 def ext_internal_in_extern_inline : Extension<
+  "%select{function|variable}0 %1 has internal linkage but is used in an "
+  "inline function with external linkage">,
+  InGroup<DiagGroup<"internal-linkage-in-inline"> >;
+def warn_internal_in_extern_inline_cxx : Warning<
   "%select{function|variable}0 %1 %select{has internal linkage|is in an anonymous"
   " namespace}2 but is used in an inline %select{function|method}3 with"
   " external linkage">,
diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index c9b1a694d0..49c84664fc 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -203,15 +203,23 @@ static void diagnoseUseOfInternalDeclInInlineFunction(Sema &S,
       return;
 
   // Don't warn unless -pedantic is on if the inline function is in the main
-  // source file. These functions will most likely not be inlined into another
-  // translation unit, so they're effectively internal.
+  // source file, and in C++ don't warn at all, since the one-definition rule is
+  // still satisfied. This function will most likely not be inlined into
+  // another translation unit, so it's effectively internal.
   bool IsInMainFile = S.getSourceManager().isFromMainFile(Loc);
-  S.Diag(Loc, IsInMainFile ? diag::ext_internal_in_extern_inline
-                           : diag::warn_internal_in_extern_inline)
-    << (bool)VD
-    << D
-    << (UsedLinkage == UniqueExternalLinkage)
-    << isa<CXXMethodDecl>(Current);
+  if (S.getLangOpts().CPlusPlus) {
+    if (IsInMainFile)
+      return;
+
+    S.Diag(Loc, diag::warn_internal_in_extern_inline_cxx)
+      << (bool)VD << D
+      << (UsedLinkage == UniqueExternalLinkage)
+      << isa<CXXMethodDecl>(Current);
+  } else {
+    S.Diag(Loc, IsInMainFile ? diag::ext_internal_in_extern_inline
+                             : diag::warn_internal_in_extern_inline)
+      << (bool)VD << D;
+  }
 
   // Suggest "static" on the inline function, if possible.
   if (!isa<CXXMethodDecl>(Current) &&
diff --git a/test/Sema/inline.c b/test/Sema/inline.c
index 99df8b1106..7f1815e467 100644
--- a/test/Sema/inline.c
+++ b/test/Sema/inline.c
@@ -1,5 +1,4 @@
 // RUN: %clang_cc1 -fsyntax-only -verify %s
-// RUN: %clang_cc1 -fsyntax-only -verify -x c++ %s
 
 #if defined(INCLUDE)
 // -------
diff --git a/test/SemaCXX/inline.cpp b/test/SemaCXX/inline.cpp
index 9ef0229c99..6f3570e3ca 100644
--- a/test/SemaCXX/inline.cpp
+++ b/test/SemaCXX/inline.cpp
@@ -95,14 +95,14 @@ inline int useStaticMainFile () {
   return staticVar; // no-warning
 }
 
-// Check that the warnings show up when explicitly requested.
+// Check that the warnings don't show up even when explicitly requested in C++.
 
 #pragma clang diagnostic push
 #pragma clang diagnostic warning "-Winternal-linkage-in-inline"
 
-inline int useStaticAgain () { // expected-note 2 {{use 'static' to give inline function 'useStaticAgain' internal linkage}}
-  anonFunction(); // expected-warning{{function 'anonFunction' is in an anonymous namespace but is used in an inline function with external linkage}}
-  return staticVar; // expected-warning{{variable 'staticVar' has internal linkage but is used in an inline function with external linkage}}
+inline int useStaticAgain () {
+  anonFunction(); // no-warning
+  return staticVar; // no-warning
 }
 
 #pragma clang diagnostic pop