-Wc++98-compat: warn if a SFINAE substitution in C++11 suppresses an access

control diagnostic.

llvm-svn: 142463

1 files changed, 25 insertions, 7 deletions

diff --git a/clang/lib/Sema/Sema.cpp b/clang/lib/Sema/Sema.cpp
index 4a9d8a5efbf..8346cc475ff 100644
--- a/clang/lib/Sema/Sema.cpp
+++ b/clang/lib/Sema/Sema.cpp
@@ -625,10 +625,19 @@ Sema::SemaDiagnosticBuilder::~SemaDiagnosticBuilder() {
   if (llvm::Optional<TemplateDeductionInfo*> Info = SemaRef.isSFINAEContext()) {
     switch (DiagnosticIDs::getDiagnosticSFINAEResponse(getDiagID())) {
     case DiagnosticIDs::SFINAE_Report:
-      // Fall through; we'll report the diagnostic below.
+      // We'll report the diagnostic below.
       break;
       
-    case DiagnosticIDs::SFINAE_AccessControl:
+    case DiagnosticIDs::SFINAE_SubstitutionFailure:
+      // Count this failure so that we know that template argument deduction
+      // has failed.
+      ++SemaRef.NumSFINAEErrors;
+      SemaRef.Diags.setLastDiagnosticIgnored();
+      SemaRef.Diags.Clear();
+      Clear();
+      return;
+      
+    case DiagnosticIDs::SFINAE_AccessControl: {
       // Per C++ Core Issue 1170, access control is part of SFINAE.
       // Additionally, the AccessCheckingSFINAE flag can be used to temporary
       // make access control a part of SFINAE for the purposes of checking
@@ -636,16 +645,25 @@ Sema::SemaDiagnosticBuilder::~SemaDiagnosticBuilder() {
       if (!SemaRef.AccessCheckingSFINAE &&
           !SemaRef.getLangOptions().CPlusPlus0x)
         break;
-        
-    case DiagnosticIDs::SFINAE_SubstitutionFailure:
-      // Count this failure so that we know that template argument deduction
-      // has failed.
+
+      SourceLocation Loc = getLocation();
+
+      // Suppress this diagnostic.
       ++SemaRef.NumSFINAEErrors;
       SemaRef.Diags.setLastDiagnosticIgnored();
       SemaRef.Diags.Clear();
       Clear();
+
+      // Now the diagnostic state is clear, produce a C++98 compatibility
+      // warning.
+      SemaRef.Diag(Loc, diag::warn_cxx98_compat_sfinae_access_control);
+
+      // The last diagnostic which Sema produced was ignored. Suppress any
+      // notes attached to it.
+      SemaRef.Diags.setLastDiagnosticIgnored();
       return;
-      
+    }
+
     case DiagnosticIDs::SFINAE_Suppress:
       // Make a copy of this suppressed diagnostic and store it with the
       // template-deduction information;