2 files changed, 51 insertions, 24 deletions

diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 617adfe3630..96b6c16485c 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -5766,6 +5766,17 @@ void Sema::ActOnEnumBody(SourceLocation EnumLoc, SourceLocation LBraceLoc,
   QualType BestType;
   unsigned BestWidth;
 
+  // C++0x N3000 [conv.prom]p3:
+  //   An rvalue of an unscoped enumeration type whose underlying
+  //   type is not fixed can be converted to an rvalue of the first
+  //   of the following types that can represent all the values of
+  //   the enumeration: int, unsigned int, long int, unsigned long
+  //   int, long long int, or unsigned long long int.
+  // C99 6.4.4.3p2:
+  //   An identifier declared as an enumeration constant has type int.
+  // The C99 rule is modified by a gcc extension 
+  QualType BestPromotionType;
+
   bool Packed = Enum->getAttr<PackedAttr>() ? true : false;
 
   if (NumNegativeBits) {
@@ -5773,22 +5784,21 @@ void Sema::ActOnEnumBody(SourceLocation EnumLoc, SourceLocation LBraceLoc,
     // int/long/longlong) that fits.
     // If it's packed, check also if it fits a char or a short.
     if (Packed && NumNegativeBits <= CharWidth && NumPositiveBits < CharWidth) {
-        BestType = Context.SignedCharTy;
-        BestWidth = CharWidth;
+      BestType = Context.SignedCharTy;
+      BestWidth = CharWidth;
     } else if (Packed && NumNegativeBits <= ShortWidth &&
                NumPositiveBits < ShortWidth) {
-        BestType = Context.ShortTy;
-        BestWidth = ShortWidth;
-    }
-    else if (NumNegativeBits <= IntWidth && NumPositiveBits < IntWidth) {
+      BestType = Context.ShortTy;
+      BestWidth = ShortWidth;
+    } else if (NumNegativeBits <= IntWidth && NumPositiveBits < IntWidth) {
       BestType = Context.IntTy;
       BestWidth = IntWidth;
     } else {
       BestWidth = Context.Target.getLongWidth();
 
-      if (NumNegativeBits <= BestWidth && NumPositiveBits < BestWidth)
+      if (NumNegativeBits <= BestWidth && NumPositiveBits < BestWidth) {
         BestType = Context.LongTy;
-      else {
+      } else {
         BestWidth = Context.Target.getLongLongWidth();
 
         if (NumNegativeBits > BestWidth || NumPositiveBits >= BestWidth)
@@ -5796,31 +5806,46 @@ void Sema::ActOnEnumBody(SourceLocation EnumLoc, SourceLocation LBraceLoc,
         BestType = Context.LongLongTy;
       }
     }
+    BestPromotionType = (BestWidth <= IntWidth ? Context.IntTy : BestType);
   } else {
     // If there is no negative value, figure out which of uint, ulong, ulonglong
     // fits.
     // If it's packed, check also if it fits a char or a short.
     if (Packed && NumPositiveBits <= CharWidth) {
-        BestType = Context.UnsignedCharTy;
-        BestWidth = CharWidth;
+      BestType = Context.UnsignedCharTy;
+      BestPromotionType = Context.IntTy;
+      BestWidth = CharWidth;
     } else if (Packed && NumPositiveBits <= ShortWidth) {
-        BestType = Context.UnsignedShortTy;
-        BestWidth = ShortWidth;
-    }
-    else if (NumPositiveBits <= IntWidth) {
+      BestType = Context.UnsignedShortTy;
+      BestPromotionType = Context.IntTy;
+      BestWidth = ShortWidth;
+    } else if (NumPositiveBits <= IntWidth) {
       BestType = Context.UnsignedIntTy;
       BestWidth = IntWidth;
+      BestPromotionType = (NumPositiveBits == BestWidth
+                           ? Context.UnsignedIntTy : Context.IntTy);
     } else if (NumPositiveBits <=
                (BestWidth = Context.Target.getLongWidth())) {
       BestType = Context.UnsignedLongTy;
+      BestPromotionType = (NumPositiveBits == BestWidth
+                           ? Context.UnsignedLongTy : Context.LongTy);
     } else {
       BestWidth = Context.Target.getLongLongWidth();
       assert(NumPositiveBits <= BestWidth &&
              "How could an initializer get larger than ULL?");
       BestType = Context.UnsignedLongLongTy;
+      BestPromotionType = (NumPositiveBits == BestWidth
+                           ? Context.UnsignedLongLongTy : Context.LongLongTy);
     }
   }
 
+  // If we're in C and the promotion type is larger than an int, just
+  // use the underlying type, which is generally the unsigned integer
+  // type of the same rank as the promotion type.  This is how the gcc
+  // extension works.
+  if (!getLangOptions().CPlusPlus && BestPromotionType != Context.IntTy)
+    BestPromotionType = BestType;
+
   // Loop over all of the enumerator constants, changing their types to match
   // the type of the enum if needed.
   for (unsigned i = 0; i != NumElements; ++i) {
@@ -5898,7 +5923,7 @@ void Sema::ActOnEnumBody(SourceLocation EnumLoc, SourceLocation LBraceLoc,
       ECD->setType(NewTy);
   }
 
-  Enum->completeDefinition(Context, BestType);
+  Enum->completeDefinition(Context, BestType, BestPromotionType);
 }
 
 Sema::DeclPtrTy Sema::ActOnFileScopeAsmDecl(SourceLocation Loc,
diff --git a/clang/lib/Sema/SemaOverload.cpp b/clang/lib/Sema/SemaOverload.cpp
index 2555f5bde60..4443de05380 100644
--- a/clang/lib/Sema/SemaOverload.cpp
+++ b/clang/lib/Sema/SemaOverload.cpp
@@ -754,19 +754,21 @@ bool Sema::IsIntegralPromotion(Expr *From, QualType FromType, QualType ToType) {
   // can be converted to an rvalue of the first of the following types
   // that can represent all the values of its underlying type: int,
   // unsigned int, long, or unsigned long (C++ 4.5p2).
-  if ((FromType->isEnumeralType() || FromType->isWideCharType())
-      && ToType->isIntegerType()) {
+
+  // We pre-calculate the promotion type for enum types.
+  if (const EnumType *FromEnumType = FromType->getAs<EnumType>())
+    if (ToType->isIntegerType())
+      return Context.hasSameUnqualifiedType(ToType,
+                                FromEnumType->getDecl()->getPromotionType());
+
+  if (FromType->isWideCharType() && ToType->isIntegerType()) {
     // Determine whether the type we're converting from is signed or
     // unsigned.
     bool FromIsSigned;
     uint64_t FromSize = Context.getTypeSize(FromType);
-    if (const EnumType *FromEnumType = FromType->getAs<EnumType>()) {
-      QualType UnderlyingType = FromEnumType->getDecl()->getIntegerType();
-      FromIsSigned = UnderlyingType->isSignedIntegerType();
-    } else {
-      // FIXME: Is wchar_t signed or unsigned? We assume it's signed for now.
-      FromIsSigned = true;
-    }
+    
+    // FIXME: Is wchar_t signed or unsigned? We assume it's signed for now.
+    FromIsSigned = true;
 
     // The types we'll try to promote to, in the appropriate
     // order. Try each of these types.