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[Sema] Allow C conversions in C overload logic 

C allows for some implicit conversions that C++ does not, e.g. void* ->
char*. This patch teaches clang that these conversions are okay when
dealing with overloads in C.

Differential Revision: http://reviews.llvm.org/D13604

llvm-svn: 249995
This commit is contained in:
George Burgess IV 2015-10-11 20:13:20 +00:00
parent fcc34bdee0
commit 4546181e12
5 changed files with 91 additions and 37 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
clang/include/clang/Sema/Overload.h
View File

@ -83,7 +83,8 @@ namespace clang {
ICK_TransparentUnionConversion, ///< Transparent Union Conversions
ICK_Writeback_Conversion, ///< Objective-C ARC writeback conversion
ICK_Zero_Event_Conversion, ///< Zero constant to event (OpenCL1.2 6.12.10)
ICK_Num_Conversion_Kinds ///< The number of conversion kinds
ICK_C_Only_Conversion, ///< Conversions allowed in C, but not C++
ICK_Num_Conversion_Kinds, ///< The number of conversion kinds
};
/// ImplicitConversionRank - The rank of an implicit conversion
@ -95,7 +96,9 @@ namespace clang {
ICR_Promotion, ///< Promotion
ICR_Conversion, ///< Conversion
ICR_Complex_Real_Conversion, ///< Complex <-> Real conversion
ICR_Writeback_Conversion ///< ObjC ARC writeback conversion
ICR_Writeback_Conversion, ///< ObjC ARC writeback conversion
ICR_C_Conversion ///< Conversion only allowed in the C standard.
/// (e.g. void* to char*)
};
ImplicitConversionRank GetConversionRank(ImplicitConversionKind Kind);

14
clang/include/clang/Sema/Sema.h
View File

@ -8292,19 +8292,23 @@ public:
QualType LHSType,
QualType RHSType);
/// Check assignment constraints and prepare for a conversion of the
/// RHS to the LHS type.
/// Check assignment constraints and optionally prepare for a conversion of
/// the RHS to the LHS type. The conversion is prepared for if ConvertRHS
/// is true.
AssignConvertType CheckAssignmentConstraints(QualType LHSType,
ExprResult &RHS,
CastKind &Kind);
CastKind &Kind,
bool ConvertRHS = true);
// CheckSingleAssignmentConstraints - Currently used by
// CheckAssignmentOperands, and ActOnReturnStmt. Prior to type checking,
// this routine performs the default function/array converions.
// this routine performs the default function/array converions, if ConvertRHS
// is true.
AssignConvertType CheckSingleAssignmentConstraints(QualType LHSType,
ExprResult &RHS,
bool Diagnose = true,
bool DiagnoseCFAudited = false);
bool DiagnoseCFAudited = false,
bool ConvertRHS = true);
// \brief If the lhs type is a transparent union, check whether we
// can initialize the transparent union with the given expression.

26
clang/lib/Sema/SemaExpr.cpp
View File

@ -6867,7 +6867,7 @@ Sema::CheckAssignmentConstraints(SourceLocation Loc,
ExprResult RHSPtr = &RHSExpr;
CastKind K = CK_Invalid;
return CheckAssignmentConstraints(LHSType, RHSPtr, K);
return CheckAssignmentConstraints(LHSType, RHSPtr, K, /*ConvertRHS=*/false);
}
/// CheckAssignmentConstraints (C99 6.5.16) - This routine currently
@ -6889,7 +6889,7 @@ Sema::CheckAssignmentConstraints(SourceLocation Loc,
/// Sets 'Kind' for any result kind except Incompatible.
Sema::AssignConvertType
Sema::CheckAssignmentConstraints(QualType LHSType, ExprResult &RHS,
CastKind &Kind) {
CastKind &Kind, bool ConvertRHS) {
QualType RHSType = RHS.get()->getType();
QualType OrigLHSType = LHSType;
@ -6911,7 +6911,7 @@ Sema::CheckAssignmentConstraints(QualType LHSType, ExprResult &RHS,
CheckAssignmentConstraints(AtomicTy->getValueType(), RHS, Kind);
if (result != Compatible)
return result;
if (Kind != CK_NoOp)
if (Kind != CK_NoOp && ConvertRHS)
RHS = ImpCastExprToType(RHS.get(), AtomicTy->getValueType(), Kind);
Kind = CK_NonAtomicToAtomic;
return Compatible;
@ -6941,7 +6941,7 @@ Sema::CheckAssignmentConstraints(QualType LHSType, ExprResult &RHS,
// CK_VectorSplat does T -> vector T, so first cast to the
// element type.
QualType elType = cast<ExtVectorType>(LHSType)->getElementType();
if (elType != RHSType) {
if (elType != RHSType && ConvertRHS) {
Kind = PrepareScalarCast(RHS, elType);
RHS = ImpCastExprToType(RHS.get(), elType, Kind);
}
@ -6974,6 +6974,7 @@ Sema::CheckAssignmentConstraints(QualType LHSType, ExprResult &RHS,
// Arithmetic conversions.
if (LHSType->isArithmeticType() && RHSType->isArithmeticType() &&
!(getLangOpts().CPlusPlus && LHSType->isEnumeralType())) {
if (ConvertRHS)
Kind = PrepareScalarCast(RHS, LHSType);
return Compatible;
}
@ -7099,6 +7100,7 @@ Sema::CheckAssignmentConstraints(QualType LHSType, ExprResult &RHS,
// Only under strict condition T^ is compatible with an Objective-C pointer.
if (RHSType->isBlockPointerType() &&
LHSType->isBlockCompatibleObjCPointerType(Context)) {
if (ConvertRHS)
maybeExtendBlockObject(RHS);
Kind = CK_BlockPointerToObjCPointerCast;
return Compatible;
@ -7225,9 +7227,16 @@ Sema::CheckTransparentUnionArgumentConstraints(QualType ArgType,
}
Sema::AssignConvertType
Sema::CheckSingleAssignmentConstraints(QualType LHSType, ExprResult &RHS,
Sema::CheckSingleAssignmentConstraints(QualType LHSType, ExprResult &CallerRHS,
bool Diagnose,
bool DiagnoseCFAudited) {
bool DiagnoseCFAudited,
bool ConvertRHS) {
// If ConvertRHS is false, we want to leave the caller's RHS untouched. Sadly,
// we can't avoid *all* modifications at the moment, so we need some somewhere
// to put the updated value.
ExprResult LocalRHS = CallerRHS;
ExprResult &RHS = ConvertRHS ? CallerRHS : LocalRHS;
if (getLangOpts().CPlusPlus) {
if (!LHSType->isRecordType() && !LHSType->isAtomicType()) {
// C++ 5.17p3: If the left operand is not of class type, the
@ -7276,6 +7285,7 @@ Sema::CheckSingleAssignmentConstraints(QualType LHSType, ExprResult &RHS,
CastKind Kind;
CXXCastPath Path;
CheckPointerConversion(RHS.get(), LHSType, Kind, Path, false);
if (ConvertRHS)
RHS = ImpCastExprToType(RHS.get(), LHSType, Kind, VK_RValue, &Path);
return Compatible;
}
@ -7287,6 +7297,7 @@ Sema::CheckSingleAssignmentConstraints(QualType LHSType, ExprResult &RHS,
//
// Suppress this for references: C++ 8.5.3p5.
if (!LHSType->isReferenceType()) {
// FIXME: We potentially allocate here even if ConvertRHS is false.
RHS = DefaultFunctionArrayLvalueConversion(RHS.get());
if (RHS.isInvalid())
return Incompatible;
@ -7303,7 +7314,7 @@ Sema::CheckSingleAssignmentConstraints(QualType LHSType, ExprResult &RHS,
CastKind Kind = CK_Invalid;
Sema::AssignConvertType result =
CheckAssignmentConstraints(LHSType, RHS, Kind);
CheckAssignmentConstraints(LHSType, RHS, Kind, ConvertRHS);
// C99 6.5.16.1p2: The value of the right operand is converted to the
// type of the assignment expression.
@ -7325,6 +7336,7 @@ Sema::CheckSingleAssignmentConstraints(QualType LHSType, ExprResult &RHS,
return Compatible;
}
if (ConvertRHS)
RHS = ImpCastExprToType(E, Ty, Kind);
}
return result;

43
clang/lib/Sema/SemaOverload.cpp
View File

@ -130,7 +130,11 @@ ImplicitConversionRank clang::GetConversionRank(ImplicitConversionKind Kind) {
ICR_Complex_Real_Conversion,
ICR_Conversion,
ICR_Conversion,
ICR_Writeback_Conversion
ICR_Writeback_Conversion,
ICR_Exact_Match, // NOTE(gbiv): This may not be completely right --
// it was omitted by the patch that added
// ICK_Zero_Event_Conversion
ICR_C_Conversion
};
return Rank[(int)Kind];
}
@ -162,7 +166,9 @@ static const char* GetImplicitConversionName(ImplicitConversionKind Kind) {
"Complex-real conversion",
"Block Pointer conversion",
"Transparent Union Conversion",
"Writeback conversion"
"Writeback conversion",
"OpenCL Zero Event Conversion",
"C specific type conversion"
};
return Name[Kind];
}
@ -1434,14 +1440,11 @@ static bool IsStandardConversion(Sema &S, Expr* From, QualType ToType,
SCS.CopyConstructor = nullptr;
// There are no standard conversions for class types in C++, so
// abort early. When overloading in C, however, we do permit
if (FromType->isRecordType() || ToType->isRecordType()) {
if (S.getLangOpts().CPlusPlus)
// abort early. When overloading in C, however, we do permit them.
if (S.getLangOpts().CPlusPlus &&
(FromType->isRecordType() || ToType->isRecordType()))
return false;
// When we're overloading in C, we allow, as standard conversions,
}
// The first conversion can be an lvalue-to-rvalue conversion,
// array-to-pointer conversion, or function-to-pointer conversion
// (C++ 4p1).
@ -1651,7 +1654,7 @@ static bool IsStandardConversion(Sema &S, Expr* From, QualType ToType,
return true;
} else if (ToType->isEventT() &&
From->isIntegerConstantExpr(S.getASTContext()) &&
(From->EvaluateKnownConstInt(S.getASTContext()) == 0)) {
From->EvaluateKnownConstInt(S.getASTContext()) == 0) {
SCS.Second = ICK_Zero_Event_Conversion;
FromType = ToType;
} else {
@ -1690,11 +1693,28 @@ static bool IsStandardConversion(Sema &S, Expr* From, QualType ToType,
}
SCS.setToType(2, FromType);
if (CanonFrom == CanonTo)
return true;
// If we have not converted the argument type to the parameter type,
// this is a bad conversion sequence.
if (CanonFrom != CanonTo)
// this is a bad conversion sequence, unless we're resolving an overload in C.
if (S.getLangOpts().CPlusPlus || !InOverloadResolution)
return false;
ExprResult ER = ExprResult{From};
auto Conv = S.CheckSingleAssignmentConstraints(ToType, ER,
/*Diagnose=*/false,
/*DiagnoseCFAudited=*/false,
/*ConvertRHS=*/false);
if (Conv != Sema::Compatible)
return false;
SCS.setAllToTypes(ToType);
// We need to set all three because we want this conversion to rank terribly,
// and we don't know what conversions it may overlap with.
SCS.First = ICK_C_Only_Conversion;
SCS.Second = ICK_C_Only_Conversion;
SCS.Third = ICK_C_Only_Conversion;
return true;
}
@ -4993,6 +5013,7 @@ static bool CheckConvertedConstantConversions(Sema &S,
case ICK_TransparentUnionConversion:
case ICK_Writeback_Conversion:
case ICK_Zero_Event_Conversion:
case ICK_C_Only_Conversion:
return false;
case ICK_Lvalue_To_Rvalue:

14
clang/test/Sema/overloadable.c
View File

@ -85,3 +85,17 @@ void local() {
void after_local_1(int) __attribute__((overloadable)); // expected-error {{conflicting types}}
void after_local_2(int); // expected-error {{must have the 'overloadable' attribute}}
void after_local_3(int) __attribute__((overloadable));
// Make sure we allow C-specific conversions in C.
void conversions() {
void foo(char *c) __attribute__((overloadable));
void foo(char *c) __attribute__((overloadable, enable_if(c, "nope.jpg")));
void *ptr;
foo(ptr);
void multi_type(unsigned char *c) __attribute__((overloadable));
void multi_type(signed char *c) __attribute__((overloadable));
unsigned char *c;
multi_type(c);
}