diff options
Diffstat (limited to 'clang/lib')
| -rw-r--r-- | clang/lib/AST/ASTContext.cpp | 30 | ||||
| -rw-r--r-- | clang/lib/AST/Expr.cpp | 4 |
2 files changed, 27 insertions, 7 deletions
diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp index 718719a904f..cafde32eb6f 100644 --- a/clang/lib/AST/ASTContext.cpp +++ b/clang/lib/AST/ASTContext.cpp @@ -4421,7 +4421,11 @@ unsigned ASTContext::getIntegerRank(const Type *T) const { QualType ASTContext::isPromotableBitField(Expr *E) const { if (E->isTypeDependent() || E->isValueDependent()) return QualType(); - + + // FIXME: We should not do this unless E->refersToBitField() is true. This + // matters in C where getSourceBitField() will find bit-fields for various + // cases where the source expression is not a bit-field designator. + FieldDecl *Field = E->getSourceBitField(); // FIXME: conditional bit-fields? if (!Field) return QualType(); @@ -4430,9 +4434,20 @@ QualType ASTContext::isPromotableBitField(Expr *E) const { uint64_t BitWidth = Field->getBitWidthValue(*this); uint64_t IntSize = getTypeSize(IntTy); - // GCC extension compatibility: if the bit-field size is less than or equal - // to the size of int, it gets promoted no matter what its type is. - // For instance, unsigned long bf : 4 gets promoted to signed int. + // C++ [conv.prom]p5: + // A prvalue for an integral bit-field can be converted to a prvalue of type + // int if int can represent all the values of the bit-field; otherwise, it + // can be converted to unsigned int if unsigned int can represent all the + // values of the bit-field. If the bit-field is larger yet, no integral + // promotion applies to it. + // C11 6.3.1.1/2: + // [For a bit-field of type _Bool, int, signed int, or unsigned int:] + // If an int can represent all values of the original type (as restricted by + // the width, for a bit-field), the value is converted to an int; otherwise, + // it is converted to an unsigned int. + // + // FIXME: C does not permit promotion of a 'long : 3' bitfield to int. + // We perform that promotion here to match GCC and C++. if (BitWidth < IntSize) return IntTy; @@ -4440,9 +4455,10 @@ QualType ASTContext::isPromotableBitField(Expr *E) const { return FT->isSignedIntegerType() ? IntTy : UnsignedIntTy; // Types bigger than int are not subject to promotions, and therefore act - // like the base type. - // FIXME: This doesn't quite match what gcc does, but what gcc does here - // is ridiculous. + // like the base type. GCC has some weird bugs in this area that we + // deliberately do not follow (GCC follows a pre-standard resolution to + // C's DR315 which treats bit-width as being part of the type, and this leaks + // into their semantics in some cases). return QualType(); } diff --git a/clang/lib/AST/Expr.cpp b/clang/lib/AST/Expr.cpp index 523db1243d7..0970d59c9c5 100644 --- a/clang/lib/AST/Expr.cpp +++ b/clang/lib/AST/Expr.cpp @@ -3278,6 +3278,10 @@ FieldDecl *Expr::getSourceBitField() { return BinOp->getRHS()->getSourceBitField(); } + if (UnaryOperator *UnOp = dyn_cast<UnaryOperator>(E)) + if (UnOp->isPrefix() && UnOp->isIncrementDecrementOp()) + return UnOp->getSubExpr()->getSourceBitField(); + return nullptr; } |
