First pass at implementing C++ enum semantics: calculate (and store) an
"integer promotion" type associated with an enum decl, and use this type to
determine which type to promote to. This type obeys C++ [conv.prom]p2 and
is therefore generally signed unless the range of the enumerators forces
it to be unsigned.
Kills off a lot of false positives from -Wsign-compare in C++, addressing
rdar://7455616
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@90965 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/AST/ASTContext.cpp b/lib/AST/ASTContext.cpp
index fcdd487..91fd166 100644
--- a/lib/AST/ASTContext.cpp
+++ b/lib/AST/ASTContext.cpp
@@ -2671,7 +2671,7 @@
unsigned ASTContext::getIntegerRank(Type *T) {
assert(T->isCanonicalUnqualified() && "T should be canonicalized");
if (EnumType* ET = dyn_cast<EnumType>(T))
- T = ET->getDecl()->getIntegerType().getTypePtr();
+ T = ET->getDecl()->getPromotionType().getTypePtr();
if (T->isSpecificBuiltinType(BuiltinType::WChar))
T = getFromTargetType(Target.getWCharType()).getTypePtr();
@@ -2752,6 +2752,8 @@
QualType ASTContext::getPromotedIntegerType(QualType Promotable) {
assert(!Promotable.isNull());
assert(Promotable->isPromotableIntegerType());
+ if (const EnumType *ET = Promotable->getAs<EnumType>())
+ return ET->getDecl()->getPromotionType();
if (Promotable->isSignedIntegerType())
return IntTy;
uint64_t PromotableSize = getTypeSize(Promotable);
@@ -4358,6 +4360,8 @@
if (LHSClass != RHSClass) {
// C99 6.7.2.2p4: Each enumerated type shall be compatible with char,
// a signed integer type, or an unsigned integer type.
+ // Compatibility is based on the underlying type, not the promotion
+ // type.
if (const EnumType* ETy = LHS->getAs<EnumType>()) {
if (ETy->getDecl()->getIntegerType() == RHSCan.getUnqualifiedType())
return RHS;
@@ -4517,6 +4521,8 @@
if (FixedWidthIntType *FWIT = dyn_cast<FixedWidthIntType>(T)) {
return FWIT->getWidth();
}
+ if (EnumType *ET = dyn_cast<EnumType>(T))
+ T = ET->getDecl()->getPromotionType();
// For builtin types, just use the standard type sizing method
return (unsigned)getTypeSize(T);
}
diff --git a/lib/AST/Decl.cpp b/lib/AST/Decl.cpp
index 42c9ef9..212dd35 100644
--- a/lib/AST/Decl.cpp
+++ b/lib/AST/Decl.cpp
@@ -195,9 +195,12 @@
Decl::Destroy(C);
}
-void EnumDecl::completeDefinition(ASTContext &C, QualType NewType) {
+void EnumDecl::completeDefinition(ASTContext &C,
+ QualType NewType,
+ QualType NewPromotionType) {
assert(!isDefinition() && "Cannot redefine enums!");
IntegerType = NewType;
+ PromotionType = NewPromotionType;
TagDecl::completeDefinition();
}
diff --git a/lib/Frontend/PCHReaderDecl.cpp b/lib/Frontend/PCHReaderDecl.cpp
index 40d48c5..01e1a41 100644
--- a/lib/Frontend/PCHReaderDecl.cpp
+++ b/lib/Frontend/PCHReaderDecl.cpp
@@ -126,6 +126,7 @@
void PCHDeclReader::VisitEnumDecl(EnumDecl *ED) {
VisitTagDecl(ED);
ED->setIntegerType(Reader.GetType(Record[Idx++]));
+ ED->setPromotionType(Reader.GetType(Record[Idx++]));
// FIXME: C++ InstantiatedFrom
}
diff --git a/lib/Frontend/PCHWriterDecl.cpp b/lib/Frontend/PCHWriterDecl.cpp
index 1ba113e..049cdb0 100644
--- a/lib/Frontend/PCHWriterDecl.cpp
+++ b/lib/Frontend/PCHWriterDecl.cpp
@@ -123,6 +123,7 @@
void PCHDeclWriter::VisitEnumDecl(EnumDecl *D) {
VisitTagDecl(D);
Writer.AddTypeRef(D->getIntegerType(), Record);
+ Writer.AddTypeRef(D->getPromotionType(), Record);
// FIXME: C++ InstantiatedFrom
Code = pch::DECL_ENUM;
}
diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index 617adfe..96b6c16 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -5766,6 +5766,17 @@
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 @@
// 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 @@
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 @@
ECD->setType(NewTy);
}
- Enum->completeDefinition(Context, BestType);
+ Enum->completeDefinition(Context, BestType, BestPromotionType);
}
Sema::DeclPtrTy Sema::ActOnFileScopeAsmDecl(SourceLocation Loc,
diff --git a/lib/Sema/SemaOverload.cpp b/lib/Sema/SemaOverload.cpp
index 2555f5b..4443de0 100644
--- a/lib/Sema/SemaOverload.cpp
+++ b/lib/Sema/SemaOverload.cpp
@@ -754,19 +754,21 @@
// 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.