Implement C++1y decltype(auto).

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@180610 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 41 insertions, 2 deletions

diff --git a/lib/Sema/DeclSpec.cpp b/lib/Sema/DeclSpec.cpp
index 7a69eef2bb..998e2c0c36 100644
--- a/lib/Sema/DeclSpec.cpp
+++ b/lib/Sema/DeclSpec.cpp
@@ -294,6 +294,11 @@ bool Declarator::isDeclarationOfFunction() const {
     case TST_event_t:
       return false;
 
+    case TST_decltype_auto:
+      // This must have an initializer, so can't be a function declaration,
+      // even if the initializer has function type.
+      return false;
+
     case TST_decltype:
     case TST_typeofExpr:
       if (Expr *E = DS.getRepAsExpr())
@@ -434,6 +439,7 @@ const char *DeclSpec::getSpecifierName(DeclSpec::TST T) {
   case DeclSpec::TST_typeofExpr:  return "typeof";
   case DeclSpec::TST_auto:        return "auto";
   case DeclSpec::TST_decltype:    return "(decltype)";
+  case DeclSpec::TST_decltype_auto: return "decltype(auto)";
   case DeclSpec::TST_underlyingType: return "__underlying_type";
   case DeclSpec::TST_unknown_anytype: return "__unknown_anytype";
   case DeclSpec::TST_atomic: return "_Atomic";
@@ -494,7 +500,7 @@ bool DeclSpec::SetStorageClassSpec(Sema &S, SCS SC, SourceLocation Loc,
   }
 
   if (StorageClassSpec != SCS_unspecified) {
-    // Maybe this is an attempt to use C++0x 'auto' outside of C++0x mode.
+    // Maybe this is an attempt to use C++11 'auto' outside of C++11 mode.
     bool isInvalid = true;
     if (TypeSpecType == TST_unspecified && S.getLangOpts().CPlusPlus) {
       if (SC == SCS_auto)
@@ -834,6 +840,39 @@ void DeclSpec::Finish(DiagnosticsEngine &D, Preprocessor &PP) {
 
   // Check the type specifier components first.
 
+  // If decltype(auto) is used, no other type specifiers are permitted.
+  if (TypeSpecType == TST_decltype_auto &&
+      (TypeSpecWidth != TSW_unspecified ||
+       TypeSpecComplex != TSC_unspecified ||
+       TypeSpecSign != TSS_unspecified ||
+       TypeAltiVecVector || TypeAltiVecPixel || TypeAltiVecBool ||
+       TypeQualifiers)) {
+    const int NumLocs = 8;
+    SourceLocation ExtraLocs[NumLocs] = {
+      TSWLoc, TSCLoc, TSSLoc, AltiVecLoc,
+      TQ_constLoc, TQ_restrictLoc, TQ_volatileLoc, TQ_atomicLoc
+    };
+    FixItHint Hints[NumLocs];
+    SourceLocation FirstLoc;
+    for (unsigned I = 0; I != NumLocs; ++I) {
+      if (!ExtraLocs[I].isInvalid()) {
+        if (FirstLoc.isInvalid() ||
+            PP.getSourceManager().isBeforeInTranslationUnit(ExtraLocs[I],
+                                                            FirstLoc))
+          FirstLoc = ExtraLocs[I];
+        Hints[I] = FixItHint::CreateRemoval(ExtraLocs[I]);
+      }
+    }
+    TypeSpecWidth = TSW_unspecified;
+    TypeSpecComplex = TSC_unspecified;
+    TypeSpecSign = TSS_unspecified;
+    TypeAltiVecVector = TypeAltiVecPixel = TypeAltiVecBool = false;
+    TypeQualifiers = 0;
+    Diag(D, TSTLoc, diag::err_decltype_auto_cannot_be_combined)
+      << Hints[0] << Hints[1] << Hints[2] << Hints[3]
+      << Hints[4] << Hints[5] << Hints[6] << Hints[7];
+  }
+
   // Validate and finalize AltiVec vector declspec.
   if (TypeAltiVecVector) {
     if (TypeAltiVecBool) {
@@ -973,7 +1012,7 @@ void DeclSpec::Finish(DiagnosticsEngine &D, Preprocessor &PP) {
     StorageClassSpecLoc = SourceLocation();
   }
   // Diagnose if we've recovered from an ill-formed 'auto' storage class
-  // specifier in a pre-C++0x dialect of C++.
+  // specifier in a pre-C++11 dialect of C++.
   if (!PP.getLangOpts().CPlusPlus11 && TypeSpecType == TST_auto)
     Diag(D, TSTLoc, diag::ext_auto_type_specifier);
   if (PP.getLangOpts().CPlusPlus && !PP.getLangOpts().CPlusPlus11 &&