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llvm-project/clang/lib/Sema/SemaOverload.cpp

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//===--- SemaOverload.cpp - C++ Overloading ---------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file provides Sema routines for C++ overloading.
//
//===----------------------------------------------------------------------===//
#include "Sema.h"
#include "SemaInherit.h"
#include "clang/Basic/Diagnostic.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/Expr.h"
#include "llvm/Support/Compiler.h"
#include <algorithm>
namespace clang {
/// GetConversionCategory - Retrieve the implicit conversion
/// category corresponding to the given implicit conversion kind.
ImplicitConversionCategory
GetConversionCategory(ImplicitConversionKind Kind) {
static const ImplicitConversionCategory
Category[(int)ICK_Num_Conversion_Kinds] = {
ICC_Identity,
ICC_Lvalue_Transformation,
ICC_Lvalue_Transformation,
ICC_Lvalue_Transformation,
ICC_Qualification_Adjustment,
ICC_Promotion,
ICC_Promotion,
ICC_Conversion,
ICC_Conversion,
ICC_Conversion,
ICC_Conversion,
ICC_Conversion,
ICC_Conversion,
ICC_Conversion
};
return Category[(int)Kind];
}
/// GetConversionRank - Retrieve the implicit conversion rank
/// corresponding to the given implicit conversion kind.
ImplicitConversionRank GetConversionRank(ImplicitConversionKind Kind) {
static const ImplicitConversionRank
Rank[(int)ICK_Num_Conversion_Kinds] = {
ICR_Exact_Match,
ICR_Exact_Match,
ICR_Exact_Match,
ICR_Exact_Match,
ICR_Exact_Match,
ICR_Promotion,
ICR_Promotion,
ICR_Conversion,
ICR_Conversion,
ICR_Conversion,
ICR_Conversion,
ICR_Conversion,
ICR_Conversion,
ICR_Conversion
};
return Rank[(int)Kind];
}
/// GetImplicitConversionName - Return the name of this kind of
/// implicit conversion.
const char* GetImplicitConversionName(ImplicitConversionKind Kind) {
static const char* Name[(int)ICK_Num_Conversion_Kinds] = {
"No conversion",
"Lvalue-to-rvalue",
"Array-to-pointer",
"Function-to-pointer",
"Qualification",
"Integral promotion",
"Floating point promotion",
"Integral conversion",
"Floating conversion",
"Floating-integral conversion",
"Pointer conversion",
"Pointer-to-member conversion",
"Boolean conversion",
"Derived-to-base conversion"
};
return Name[Kind];
}
/// StandardConversionSequence - Set the standard conversion
/// sequence to the identity conversion.
void StandardConversionSequence::setAsIdentityConversion() {
First = ICK_Identity;
Second = ICK_Identity;
Third = ICK_Identity;
Deprecated = false;
ReferenceBinding = false;
DirectBinding = false;
CopyConstructor = 0;
}
/// getRank - Retrieve the rank of this standard conversion sequence
/// (C++ 13.3.3.1.1p3). The rank is the largest rank of each of the
/// implicit conversions.
ImplicitConversionRank StandardConversionSequence::getRank() const {
ImplicitConversionRank Rank = ICR_Exact_Match;
if (GetConversionRank(First) > Rank)
Rank = GetConversionRank(First);
if (GetConversionRank(Second) > Rank)
Rank = GetConversionRank(Second);
if (GetConversionRank(Third) > Rank)
Rank = GetConversionRank(Third);
return Rank;
}
/// isPointerConversionToBool - Determines whether this conversion is
/// a conversion of a pointer or pointer-to-member to bool. This is
/// used as part of the ranking of standard conversion sequences
/// (C++ 13.3.3.2p4).
bool StandardConversionSequence::isPointerConversionToBool() const
{
QualType FromType = QualType::getFromOpaquePtr(FromTypePtr);
QualType ToType = QualType::getFromOpaquePtr(ToTypePtr);
// Note that FromType has not necessarily been transformed by the
// array-to-pointer or function-to-pointer implicit conversions, so
// check for their presence as well as checking whether FromType is
// a pointer.
if (ToType->isBooleanType() &&
(FromType->isPointerType() ||
First == ICK_Array_To_Pointer || First == ICK_Function_To_Pointer))
return true;
return false;
}
/// isPointerConversionToVoidPointer - Determines whether this
/// conversion is a conversion of a pointer to a void pointer. This is
/// used as part of the ranking of standard conversion sequences (C++
/// 13.3.3.2p4).
bool
StandardConversionSequence::
isPointerConversionToVoidPointer(ASTContext& Context) const
{
QualType FromType = QualType::getFromOpaquePtr(FromTypePtr);
QualType ToType = QualType::getFromOpaquePtr(ToTypePtr);
// Note that FromType has not necessarily been transformed by the
// array-to-pointer implicit conversion, so check for its presence
// and redo the conversion to get a pointer.
if (First == ICK_Array_To_Pointer)
FromType = Context.getArrayDecayedType(FromType);
if (Second == ICK_Pointer_Conversion)
if (const PointerType* ToPtrType = ToType->getAsPointerType())
return ToPtrType->getPointeeType()->isVoidType();
return false;
}
/// DebugPrint - Print this standard conversion sequence to standard
/// error. Useful for debugging overloading issues.
void StandardConversionSequence::DebugPrint() const {
bool PrintedSomething = false;
if (First != ICK_Identity) {
fprintf(stderr, "%s", GetImplicitConversionName(First));
PrintedSomething = true;
}
if (Second != ICK_Identity) {
if (PrintedSomething) {
fprintf(stderr, " -> ");
}
fprintf(stderr, "%s", GetImplicitConversionName(Second));
if (CopyConstructor) {
fprintf(stderr, " (by copy constructor)");
} else if (DirectBinding) {
fprintf(stderr, " (direct reference binding)");
} else if (ReferenceBinding) {
fprintf(stderr, " (reference binding)");
}
PrintedSomething = true;
}
if (Third != ICK_Identity) {
if (PrintedSomething) {
fprintf(stderr, " -> ");
}
fprintf(stderr, "%s", GetImplicitConversionName(Third));
PrintedSomething = true;
}
if (!PrintedSomething) {
fprintf(stderr, "No conversions required");
}
}
/// DebugPrint - Print this user-defined conversion sequence to standard
/// error. Useful for debugging overloading issues.
void UserDefinedConversionSequence::DebugPrint() const {
if (Before.First || Before.Second || Before.Third) {
Before.DebugPrint();
fprintf(stderr, " -> ");
}
fprintf(stderr, "'%s'", ConversionFunction->getName());
if (After.First || After.Second || After.Third) {
fprintf(stderr, " -> ");
After.DebugPrint();
}
}
/// DebugPrint - Print this implicit conversion sequence to standard
/// error. Useful for debugging overloading issues.
void ImplicitConversionSequence::DebugPrint() const {
switch (ConversionKind) {
case StandardConversion:
fprintf(stderr, "Standard conversion: ");
Standard.DebugPrint();
break;
case UserDefinedConversion:
fprintf(stderr, "User-defined conversion: ");
UserDefined.DebugPrint();
break;
case EllipsisConversion:
fprintf(stderr, "Ellipsis conversion");
break;
case BadConversion:
fprintf(stderr, "Bad conversion");
break;
}
fprintf(stderr, "\n");
}
// IsOverload - Determine whether the given New declaration is an
// overload of the Old declaration. This routine returns false if New
// and Old cannot be overloaded, e.g., if they are functions with the
// same signature (C++ 1.3.10) or if the Old declaration isn't a
// function (or overload set). When it does return false and Old is an
// OverloadedFunctionDecl, MatchedDecl will be set to point to the
// FunctionDecl that New cannot be overloaded with.
//
// Example: Given the following input:
//
// void f(int, float); // #1
// void f(int, int); // #2
// int f(int, int); // #3
//
// When we process #1, there is no previous declaration of "f",
// so IsOverload will not be used.
//
// When we process #2, Old is a FunctionDecl for #1. By comparing the
// parameter types, we see that #1 and #2 are overloaded (since they
// have different signatures), so this routine returns false;
// MatchedDecl is unchanged.
//
// When we process #3, Old is an OverloadedFunctionDecl containing #1
// and #2. We compare the signatures of #3 to #1 (they're overloaded,
// so we do nothing) and then #3 to #2. Since the signatures of #3 and
// #2 are identical (return types of functions are not part of the
// signature), IsOverload returns false and MatchedDecl will be set to
// point to the FunctionDecl for #2.
bool
Sema::IsOverload(FunctionDecl *New, Decl* OldD,
OverloadedFunctionDecl::function_iterator& MatchedDecl)
{
if (OverloadedFunctionDecl* Ovl = dyn_cast<OverloadedFunctionDecl>(OldD)) {
// Is this new function an overload of every function in the
// overload set?
OverloadedFunctionDecl::function_iterator Func = Ovl->function_begin(),
FuncEnd = Ovl->function_end();
for (; Func != FuncEnd; ++Func) {
if (!IsOverload(New, *Func, MatchedDecl)) {
MatchedDecl = Func;
return false;
}
}
// This function overloads every function in the overload set.
return true;
} else if (FunctionDecl* Old = dyn_cast<FunctionDecl>(OldD)) {
// Is the function New an overload of the function Old?
QualType OldQType = Context.getCanonicalType(Old->getType());
QualType NewQType = Context.getCanonicalType(New->getType());
// Compare the signatures (C++ 1.3.10) of the two functions to
// determine whether they are overloads. If we find any mismatch
// in the signature, they are overloads.
// If either of these functions is a K&R-style function (no
// prototype), then we consider them to have matching signatures.
if (isa<FunctionTypeNoProto>(OldQType.getTypePtr()) ||
isa<FunctionTypeNoProto>(NewQType.getTypePtr()))
return false;
FunctionTypeProto* OldType = cast<FunctionTypeProto>(OldQType.getTypePtr());
FunctionTypeProto* NewType = cast<FunctionTypeProto>(NewQType.getTypePtr());
// The signature of a function includes the types of its
// parameters (C++ 1.3.10), which includes the presence or absence
// of the ellipsis; see C++ DR 357).
if (OldQType != NewQType &&
(OldType->getNumArgs() != NewType->getNumArgs() ||
OldType->isVariadic() != NewType->isVariadic() ||
!std::equal(OldType->arg_type_begin(), OldType->arg_type_end(),
NewType->arg_type_begin())))
return true;
// If the function is a class member, its signature includes the
// cv-qualifiers (if any) on the function itself.
//
// As part of this, also check whether one of the member functions
// is static, in which case they are not overloads (C++
// 13.1p2). While not part of the definition of the signature,
// this check is important to determine whether these functions
// can be overloaded.
CXXMethodDecl* OldMethod = dyn_cast<CXXMethodDecl>(Old);
CXXMethodDecl* NewMethod = dyn_cast<CXXMethodDecl>(New);
if (OldMethod && NewMethod &&
!OldMethod->isStatic() && !NewMethod->isStatic() &&
OldQType.getCVRQualifiers() != NewQType.getCVRQualifiers())
return true;
// The signatures match; this is not an overload.
return false;
} else {
// (C++ 13p1):
// Only function declarations can be overloaded; object and type
// declarations cannot be overloaded.
return false;
}
}
/// TryImplicitConversion - Attempt to perform an implicit conversion
/// from the given expression (Expr) to the given type (ToType). This
/// function returns an implicit conversion sequence that can be used
/// to perform the initialization. Given
///
/// void f(float f);
/// void g(int i) { f(i); }
///
/// this routine would produce an implicit conversion sequence to
/// describe the initialization of f from i, which will be a standard
/// conversion sequence containing an lvalue-to-rvalue conversion (C++
/// 4.1) followed by a floating-integral conversion (C++ 4.9).
//
/// Note that this routine only determines how the conversion can be
/// performed; it does not actually perform the conversion. As such,
/// it will not produce any diagnostics if no conversion is available,
/// but will instead return an implicit conversion sequence of kind
/// "BadConversion".
///
/// If @p SuppressUserConversions, then user-defined conversions are
/// not permitted.
ImplicitConversionSequence
Sema::TryImplicitConversion(Expr* From, QualType ToType,
bool SuppressUserConversions)
{
ImplicitConversionSequence ICS;
if (IsStandardConversion(From, ToType, ICS.Standard))
ICS.ConversionKind = ImplicitConversionSequence::StandardConversion;
else if (!SuppressUserConversions &&
IsUserDefinedConversion(From, ToType, ICS.UserDefined)) {
ICS.ConversionKind = ImplicitConversionSequence::UserDefinedConversion;
// C++ [over.ics.user]p4:
// A conversion of an expression of class type to the same class
// type is given Exact Match rank, and a conversion of an
// expression of class type to a base class of that type is
// given Conversion rank, in spite of the fact that a copy
// constructor (i.e., a user-defined conversion function) is
// called for those cases.
if (CXXConstructorDecl *Constructor
= dyn_cast<CXXConstructorDecl>(ICS.UserDefined.ConversionFunction)) {
if (Constructor->isCopyConstructor(Context)) {
// Turn this into a "standard" conversion sequence, so that it
// gets ranked with standard conversion sequences.
ICS.ConversionKind = ImplicitConversionSequence::StandardConversion;
ICS.Standard.setAsIdentityConversion();
ICS.Standard.FromTypePtr = From->getType().getAsOpaquePtr();
ICS.Standard.ToTypePtr = ToType.getAsOpaquePtr();
ICS.Standard.CopyConstructor = Constructor;
if (IsDerivedFrom(From->getType().getUnqualifiedType(),
ToType.getUnqualifiedType()))
ICS.Standard.Second = ICK_Derived_To_Base;
}
}
} else
ICS.ConversionKind = ImplicitConversionSequence::BadConversion;
return ICS;
}
/// IsStandardConversion - Determines whether there is a standard
/// conversion sequence (C++ [conv], C++ [over.ics.scs]) from the
/// expression From to the type ToType. Standard conversion sequences
/// only consider non-class types; for conversions that involve class
/// types, use TryImplicitConversion. If a conversion exists, SCS will
/// contain the standard conversion sequence required to perform this
/// conversion and this routine will return true. Otherwise, this
/// routine will return false and the value of SCS is unspecified.
bool
Sema::IsStandardConversion(Expr* From, QualType ToType,
StandardConversionSequence &SCS)
{
QualType FromType = From->getType();
// There are no standard conversions for class types, so abort early.
if (FromType->isRecordType() || ToType->isRecordType())
return false;
// Standard conversions (C++ [conv])
SCS.Deprecated = false;
SCS.FromTypePtr = FromType.getAsOpaquePtr();
SCS.CopyConstructor = 0;
// The first conversion can be an lvalue-to-rvalue conversion,
// array-to-pointer conversion, or function-to-pointer conversion
// (C++ 4p1).
// Lvalue-to-rvalue conversion (C++ 4.1):
// An lvalue (3.10) of a non-function, non-array type T can be
// converted to an rvalue.
Expr::isLvalueResult argIsLvalue = From->isLvalue(Context);
if (argIsLvalue == Expr::LV_Valid &&
!FromType->isFunctionType() && !FromType->isArrayType() &&
!FromType->isOverloadType()) {
SCS.First = ICK_Lvalue_To_Rvalue;
// If T is a non-class type, the type of the rvalue is the
// cv-unqualified version of T. Otherwise, the type of the rvalue
// is T (C++ 4.1p1).
FromType = FromType.getUnqualifiedType();
}
// Array-to-pointer conversion (C++ 4.2)
else if (FromType->isArrayType()) {
SCS.First = ICK_Array_To_Pointer;
// An lvalue or rvalue of type "array of N T" or "array of unknown
// bound of T" can be converted to an rvalue of type "pointer to
// T" (C++ 4.2p1).
FromType = Context.getArrayDecayedType(FromType);
if (IsStringLiteralToNonConstPointerConversion(From, ToType)) {
// This conversion is deprecated. (C++ D.4).
SCS.Deprecated = true;
// For the purpose of ranking in overload resolution
// (13.3.3.1.1), this conversion is considered an
// array-to-pointer conversion followed by a qualification
// conversion (4.4). (C++ 4.2p2)
SCS.Second = ICK_Identity;
SCS.Third = ICK_Qualification;
SCS.ToTypePtr = ToType.getAsOpaquePtr();
return true;
}
}
// Function-to-pointer conversion (C++ 4.3).
else if (FromType->isFunctionType() && argIsLvalue == Expr::LV_Valid) {
SCS.First = ICK_Function_To_Pointer;
// An lvalue of function type T can be converted to an rvalue of
// type "pointer to T." The result is a pointer to the
// function. (C++ 4.3p1).
FromType = Context.getPointerType(FromType);
}
// Address of overloaded function (C++ [over.over]).
else if (FunctionDecl *Fn
= ResolveAddressOfOverloadedFunction(From, ToType, false)) {
SCS.First = ICK_Function_To_Pointer;
// We were able to resolve the address of the overloaded function,
// so we can convert to the type of that function.
FromType = Fn->getType();
if (ToType->isReferenceType())
FromType = Context.getReferenceType(FromType);
else
FromType = Context.getPointerType(FromType);
}
// We don't require any conversions for the first step.
else {
SCS.First = ICK_Identity;
}
// The second conversion can be an integral promotion, floating
// point promotion, integral conversion, floating point conversion,
// floating-integral conversion, pointer conversion,
// pointer-to-member conversion, or boolean conversion (C++ 4p1).
if (Context.getCanonicalType(FromType).getUnqualifiedType() ==
Context.getCanonicalType(ToType).getUnqualifiedType()) {
// The unqualified versions of the types are the same: there's no
// conversion to do.
SCS.Second = ICK_Identity;
}
// Integral promotion (C++ 4.5).
else if (IsIntegralPromotion(From, FromType, ToType)) {
SCS.Second = ICK_Integral_Promotion;
FromType = ToType.getUnqualifiedType();
}
// Floating point promotion (C++ 4.6).
else if (IsFloatingPointPromotion(FromType, ToType)) {
SCS.Second = ICK_Floating_Promotion;
FromType = ToType.getUnqualifiedType();
}
// Integral conversions (C++ 4.7).
// FIXME: isIntegralType shouldn't be true for enums in C++.
else if ((FromType->isIntegralType() || FromType->isEnumeralType()) &&
(ToType->isIntegralType() && !ToType->isEnumeralType())) {
SCS.Second = ICK_Integral_Conversion;
FromType = ToType.getUnqualifiedType();
}
// Floating point conversions (C++ 4.8).
else if (FromType->isFloatingType() && ToType->isFloatingType()) {
SCS.Second = ICK_Floating_Conversion;
FromType = ToType.getUnqualifiedType();
}
// Floating-integral conversions (C++ 4.9).
// FIXME: isIntegralType shouldn't be true for enums in C++.
else if ((FromType->isFloatingType() &&
ToType->isIntegralType() && !ToType->isBooleanType() &&
!ToType->isEnumeralType()) ||
((FromType->isIntegralType() || FromType->isEnumeralType()) &&
ToType->isFloatingType())) {
SCS.Second = ICK_Floating_Integral;
FromType = ToType.getUnqualifiedType();
}
// Pointer conversions (C++ 4.10).
else if (IsPointerConversion(From, FromType, ToType, FromType)) {
SCS.Second = ICK_Pointer_Conversion;
}
// FIXME: Pointer to member conversions (4.11).
// Boolean conversions (C++ 4.12).
// FIXME: pointer-to-member type
else if (ToType->isBooleanType() &&
(FromType->isArithmeticType() ||
FromType->isEnumeralType() ||
FromType->isPointerType())) {
SCS.Second = ICK_Boolean_Conversion;
FromType = Context.BoolTy;
} else {
// No second conversion required.
SCS.Second = ICK_Identity;
}
QualType CanonFrom;
QualType CanonTo;
// The third conversion can be a qualification conversion (C++ 4p1).
if (IsQualificationConversion(FromType, ToType)) {
SCS.Third = ICK_Qualification;
FromType = ToType;
CanonFrom = Context.getCanonicalType(FromType);
CanonTo = Context.getCanonicalType(ToType);
} else {
// No conversion required
SCS.Third = ICK_Identity;
// C++ [over.best.ics]p6:
// [...] Any difference in top-level cv-qualification is
// subsumed by the initialization itself and does not constitute
// a conversion. [...]
CanonFrom = Context.getCanonicalType(FromType);
CanonTo = Context.getCanonicalType(ToType);
if (CanonFrom.getUnqualifiedType() == CanonTo.getUnqualifiedType() &&
CanonFrom.getCVRQualifiers() != CanonTo.getCVRQualifiers()) {
FromType = ToType;
CanonFrom = CanonTo;
}
}
// If we have not converted the argument type to the parameter type,
// this is a bad conversion sequence.
if (CanonFrom != CanonTo)
return false;
SCS.ToTypePtr = FromType.getAsOpaquePtr();
return true;
}
/// IsIntegralPromotion - Determines whether the conversion from the
/// expression From (whose potentially-adjusted type is FromType) to
/// ToType is an integral promotion (C++ 4.5). If so, returns true and
/// sets PromotedType to the promoted type.
bool Sema::IsIntegralPromotion(Expr *From, QualType FromType, QualType ToType)
{
const BuiltinType *To = ToType->getAsBuiltinType();
// All integers are built-in.
if (!To) {
return false;
}
// An rvalue of type char, signed char, unsigned char, short int, or
// unsigned short int can be converted to an rvalue of type int if
// int can represent all the values of the source type; otherwise,
// the source rvalue can be converted to an rvalue of type unsigned
// int (C++ 4.5p1).
if (FromType->isPromotableIntegerType() && !FromType->isBooleanType()) {
if (// We can promote any signed, promotable integer type to an int
(FromType->isSignedIntegerType() ||
// We can promote any unsigned integer type whose size is
// less than int to an int.
(!FromType->isSignedIntegerType() &&
Context.getTypeSize(FromType) < Context.getTypeSize(ToType)))) {
return To->getKind() == BuiltinType::Int;
}
return To->getKind() == BuiltinType::UInt;
}
// An rvalue of type wchar_t (3.9.1) or an enumeration type (7.2)
// 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()) {
// 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->getAsEnumType()) {
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;
}
// The types we'll try to promote to, in the appropriate
// order. Try each of these types.
QualType PromoteTypes[4] = {
Context.IntTy, Context.UnsignedIntTy,
Context.LongTy, Context.UnsignedLongTy
};
for (int Idx = 0; Idx < 0; ++Idx) {
uint64_t ToSize = Context.getTypeSize(PromoteTypes[Idx]);
if (FromSize < ToSize ||
(FromSize == ToSize &&
FromIsSigned == PromoteTypes[Idx]->isSignedIntegerType())) {
// We found the type that we can promote to. If this is the
// type we wanted, we have a promotion. Otherwise, no
// promotion.
return Context.getCanonicalType(ToType).getUnqualifiedType()
== Context.getCanonicalType(PromoteTypes[Idx]).getUnqualifiedType();
}
}
}
// An rvalue for an integral bit-field (9.6) can be converted to an
// rvalue 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. If the bit-field has an enumerated type, it is treated as any
// other value of that type for promotion purposes (C++ 4.5p3).
if (MemberExpr *MemRef = dyn_cast<MemberExpr>(From)) {
using llvm::APSInt;
FieldDecl *MemberDecl = MemRef->getMemberDecl();
APSInt BitWidth;
if (MemberDecl->isBitField() &&
FromType->isIntegralType() && !FromType->isEnumeralType() &&
From->isIntegerConstantExpr(BitWidth, Context)) {
APSInt ToSize(Context.getTypeSize(ToType));
// Are we promoting to an int from a bitfield that fits in an int?
if (BitWidth < ToSize ||
(FromType->isSignedIntegerType() && BitWidth <= ToSize)) {
return To->getKind() == BuiltinType::Int;
}
// Are we promoting to an unsigned int from an unsigned bitfield
// that fits into an unsigned int?
if (FromType->isUnsignedIntegerType() && BitWidth <= ToSize) {
return To->getKind() == BuiltinType::UInt;
}
return false;
}
}
// An rvalue of type bool can be converted to an rvalue of type int,
// with false becoming zero and true becoming one (C++ 4.5p4).
if (FromType->isBooleanType() && To->getKind() == BuiltinType::Int) {
return true;
}
return false;
}
/// IsFloatingPointPromotion - Determines whether the conversion from
/// FromType to ToType is a floating point promotion (C++ 4.6). If so,
/// returns true and sets PromotedType to the promoted type.
bool Sema::IsFloatingPointPromotion(QualType FromType, QualType ToType)
{
/// An rvalue of type float can be converted to an rvalue of type
/// double. (C++ 4.6p1).
if (const BuiltinType *FromBuiltin = FromType->getAsBuiltinType())
if (const BuiltinType *ToBuiltin = ToType->getAsBuiltinType())
if (FromBuiltin->getKind() == BuiltinType::Float &&
ToBuiltin->getKind() == BuiltinType::Double)
return true;
return false;
}
/// IsPointerConversion - Determines whether the conversion of the
/// expression From, which has the (possibly adjusted) type FromType,
/// can be converted to the type ToType via a pointer conversion (C++
/// 4.10). If so, returns true and places the converted type (that
/// might differ from ToType in its cv-qualifiers at some level) into
/// ConvertedType.
bool Sema::IsPointerConversion(Expr *From, QualType FromType, QualType ToType,
QualType& ConvertedType)
{
const PointerType* ToTypePtr = ToType->getAsPointerType();
if (!ToTypePtr)
return false;
// A null pointer constant can be converted to a pointer type (C++ 4.10p1).
if (From->isNullPointerConstant(Context)) {
ConvertedType = ToType;
return true;
}
// An rvalue of type "pointer to cv T," where T is an object type,
// can be converted to an rvalue of type "pointer to cv void" (C++
// 4.10p2).
if (FromType->isPointerType() &&
FromType->getAsPointerType()->getPointeeType()->isObjectType() &&
ToTypePtr->getPointeeType()->isVoidType()) {
// We need to produce a pointer to cv void, where cv is the same
// set of cv-qualifiers as we had on the incoming pointee type.
QualType toPointee = ToTypePtr->getPointeeType();
unsigned Quals = Context.getCanonicalType(FromType)->getAsPointerType()
->getPointeeType().getCVRQualifiers();
if (Context.getCanonicalType(ToTypePtr->getPointeeType()).getCVRQualifiers()
== Quals) {
// ToType is exactly the type we want. Use it.
ConvertedType = ToType;
} else {
// Build a new type with the right qualifiers.
ConvertedType
= Context.getPointerType(Context.VoidTy.getQualifiedType(Quals));
}
return true;
}
// C++ [conv.ptr]p3:
//
// An rvalue of type "pointer to cv D," where D is a class type,
// can be converted to an rvalue of type "pointer to cv B," where
// B is a base class (clause 10) of D. If B is an inaccessible
// (clause 11) or ambiguous (10.2) base class of D, a program that
// necessitates this conversion is ill-formed. The result of the
// conversion is a pointer to the base class sub-object of the
// derived class object. The null pointer value is converted to
// the null pointer value of the destination type.
//
// Note that we do not check for ambiguity or inaccessibility
// here. That is handled by CheckPointerConversion.
if (const PointerType *FromPtrType = FromType->getAsPointerType())
if (const PointerType *ToPtrType = ToType->getAsPointerType()) {
if (FromPtrType->getPointeeType()->isRecordType() &&
ToPtrType->getPointeeType()->isRecordType() &&
IsDerivedFrom(FromPtrType->getPointeeType(),
ToPtrType->getPointeeType())) {
// The conversion is okay. Now, we need to produce the type
// that results from this conversion, which will have the same
// qualifiers as the incoming type.
QualType CanonFromPointee
= Context.getCanonicalType(FromPtrType->getPointeeType());
QualType ToPointee = ToPtrType->getPointeeType();
QualType CanonToPointee = Context.getCanonicalType(ToPointee);
unsigned Quals = CanonFromPointee.getCVRQualifiers();
if (CanonToPointee.getCVRQualifiers() == Quals) {
// ToType is exactly the type we want. Use it.
ConvertedType = ToType;
} else {
// Build a new type with the right qualifiers.
ConvertedType
= Context.getPointerType(CanonToPointee.getQualifiedType(Quals));
}
return true;
}
}
return false;
}
/// CheckPointerConversion - Check the pointer conversion from the
/// expression From to the type ToType. This routine checks for
/// ambiguous (FIXME: or inaccessible) derived-to-base pointer
/// conversions for which IsPointerConversion has already returned
/// true. It returns true and produces a diagnostic if there was an
/// error, or returns false otherwise.
bool Sema::CheckPointerConversion(Expr *From, QualType ToType) {
QualType FromType = From->getType();
if (const PointerType *FromPtrType = FromType->getAsPointerType())
if (const PointerType *ToPtrType = ToType->getAsPointerType()) {
BasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/false,
/*DetectVirtual=*/false);
QualType FromPointeeType = FromPtrType->getPointeeType(),
ToPointeeType = ToPtrType->getPointeeType();
if (FromPointeeType->isRecordType() &&
ToPointeeType->isRecordType()) {
// We must have a derived-to-base conversion. Check an
// ambiguous or inaccessible conversion.
return CheckDerivedToBaseConversion(FromPointeeType, ToPointeeType,
From->getExprLoc(),
From->getSourceRange());
}
}
return false;
}
/// IsQualificationConversion - Determines whether the conversion from
/// an rvalue of type FromType to ToType is a qualification conversion
/// (C++ 4.4).
bool
Sema::IsQualificationConversion(QualType FromType, QualType ToType)
{
FromType = Context.getCanonicalType(FromType);
ToType = Context.getCanonicalType(ToType);
// If FromType and ToType are the same type, this is not a
// qualification conversion.
if (FromType == ToType)
return false;
// (C++ 4.4p4):
// A conversion can add cv-qualifiers at levels other than the first
// in multi-level pointers, subject to the following rules: [...]
bool PreviousToQualsIncludeConst = true;
bool UnwrappedAnyPointer = false;
while (UnwrapSimilarPointerTypes(FromType, ToType)) {
// Within each iteration of the loop, we check the qualifiers to
// determine if this still looks like a qualification
// conversion. Then, if all is well, we unwrap one more level of
// pointers or pointers-to-members and do it all again
// until there are no more pointers or pointers-to-members left to
// unwrap.
UnwrappedAnyPointer = true;
// -- for every j > 0, if const is in cv 1,j then const is in cv
// 2,j, and similarly for volatile.
if (!ToType.isAtLeastAsQualifiedAs(FromType))
return false;
// -- if the cv 1,j and cv 2,j are different, then const is in
// every cv for 0 < k < j.
if (FromType.getCVRQualifiers() != ToType.getCVRQualifiers()
&& !PreviousToQualsIncludeConst)
return false;
// Keep track of whether all prior cv-qualifiers in the "to" type
// include const.
PreviousToQualsIncludeConst
= PreviousToQualsIncludeConst && ToType.isConstQualified();
}
// We are left with FromType and ToType being the pointee types
// after unwrapping the original FromType and ToType the same number
// of types. If we unwrapped any pointers, and if FromType and
// ToType have the same unqualified type (since we checked
// qualifiers above), then this is a qualification conversion.
return UnwrappedAnyPointer &&
FromType.getUnqualifiedType() == ToType.getUnqualifiedType();
}
/// IsUserDefinedConversion - Determines whether there is a
/// user-defined conversion sequence (C++ [over.ics.user]) that
/// converts expression From to the type ToType. If such a conversion
/// exists, User will contain the user-defined conversion sequence
/// that performs such a conversion and this routine will return
/// true. Otherwise, this routine returns false and User is
/// unspecified.
bool Sema::IsUserDefinedConversion(Expr *From, QualType ToType,
UserDefinedConversionSequence& User)
{
OverloadCandidateSet CandidateSet;
if (const CXXRecordType *ToRecordType
= dyn_cast_or_null<CXXRecordType>(ToType->getAsRecordType())) {
// C++ [over.match.ctor]p1:
// When objects of class type are direct-initialized (8.5), or
// copy-initialized from an expression of the same or a
// derived class type (8.5), overload resolution selects the
// constructor. [...] For copy-initialization, the candidate
// functions are all the converting constructors (12.3.1) of
// that class. The argument list is the expression-list within
// the parentheses of the initializer.
CXXRecordDecl *ToRecordDecl = ToRecordType->getDecl();
const OverloadedFunctionDecl *Constructors = ToRecordDecl->getConstructors();
for (OverloadedFunctionDecl::function_const_iterator func
= Constructors->function_begin();
func != Constructors->function_end(); ++func) {
CXXConstructorDecl *Constructor = cast<CXXConstructorDecl>(*func);
if (Constructor->isConvertingConstructor())
AddOverloadCandidate(Constructor, &From, 1, CandidateSet,
/*SuppressUserConversions=*/true);
}
}
if (const CXXRecordType *FromRecordType
= dyn_cast_or_null<CXXRecordType>(From->getType()->getAsRecordType())) {
// Add all of the conversion functions as candidates.
// FIXME: Look for conversions in base classes!
CXXRecordDecl *FromRecordDecl = FromRecordType->getDecl();
OverloadedFunctionDecl *Conversions
= FromRecordDecl->getConversionFunctions();
for (OverloadedFunctionDecl::function_iterator Func
= Conversions->function_begin();
Func != Conversions->function_end(); ++Func) {
CXXConversionDecl *Conv = cast<CXXConversionDecl>(*Func);
AddConversionCandidate(Conv, From, ToType, CandidateSet);
}
}
OverloadCandidateSet::iterator Best;
switch (BestViableFunction(CandidateSet, Best)) {
case OR_Success:
// Record the standard conversion we used and the conversion function.
if (CXXConstructorDecl *Constructor
= dyn_cast<CXXConstructorDecl>(Best->Function)) {
// C++ [over.ics.user]p1:
// If the user-defined conversion is specified by a
// constructor (12.3.1), the initial standard conversion
// sequence converts the source type to the type required by
// the argument of the constructor.
//
// FIXME: What about ellipsis conversions?
QualType ThisType = Constructor->getThisType(Context);
User.Before = Best->Conversions[0].Standard;
User.ConversionFunction = Constructor;
User.After.setAsIdentityConversion();
User.After.FromTypePtr
= ThisType->getAsPointerType()->getPointeeType().getAsOpaquePtr();
User.After.ToTypePtr = ToType.getAsOpaquePtr();
return true;
} else if (CXXConversionDecl *Conversion
= dyn_cast<CXXConversionDecl>(Best->Function)) {
// C++ [over.ics.user]p1:
//
// [...] If the user-defined conversion is specified by a
// conversion function (12.3.2), the initial standard
// conversion sequence converts the source type to the
// implicit object parameter of the conversion function.
User.Before = Best->Conversions[0].Standard;
User.ConversionFunction = Conversion;
// C++ [over.ics.user]p2:
// The second standard conversion sequence converts the
// result of the user-defined conversion to the target type
// for the sequence. Since an implicit conversion sequence
// is an initialization, the special rules for
// initialization by user-defined conversion apply when
// selecting the best user-defined conversion for a
// user-defined conversion sequence (see 13.3.3 and
// 13.3.3.1).
User.After = Best->FinalConversion;
return true;
} else {
assert(false && "Not a constructor or conversion function?");
return false;
}
case OR_No_Viable_Function:
// No conversion here! We're done.
return false;
case OR_Ambiguous:
// FIXME: See C++ [over.best.ics]p10 for the handling of
// ambiguous conversion sequences.
return false;
}
return false;
}
/// CompareImplicitConversionSequences - Compare two implicit
/// conversion sequences to determine whether one is better than the
/// other or if they are indistinguishable (C++ 13.3.3.2).
ImplicitConversionSequence::CompareKind
Sema::CompareImplicitConversionSequences(const ImplicitConversionSequence& ICS1,
const ImplicitConversionSequence& ICS2)
{
// (C++ 13.3.3.2p2): When comparing the basic forms of implicit
// conversion sequences (as defined in 13.3.3.1)
// -- a standard conversion sequence (13.3.3.1.1) is a better
// conversion sequence than a user-defined conversion sequence or
// an ellipsis conversion sequence, and
// -- a user-defined conversion sequence (13.3.3.1.2) is a better
// conversion sequence than an ellipsis conversion sequence
// (13.3.3.1.3).
//
if (ICS1.ConversionKind < ICS2.ConversionKind)
return ImplicitConversionSequence::Better;
else if (ICS2.ConversionKind < ICS1.ConversionKind)
return ImplicitConversionSequence::Worse;
// Two implicit conversion sequences of the same form are
// indistinguishable conversion sequences unless one of the
// following rules apply: (C++ 13.3.3.2p3):
if (ICS1.ConversionKind == ImplicitConversionSequence::StandardConversion)
return CompareStandardConversionSequences(ICS1.Standard, ICS2.Standard);
else if (ICS1.ConversionKind ==
ImplicitConversionSequence::UserDefinedConversion) {
// User-defined conversion sequence U1 is a better conversion
// sequence than another user-defined conversion sequence U2 if
// they contain the same user-defined conversion function or
// constructor and if the second standard conversion sequence of
// U1 is better than the second standard conversion sequence of
// U2 (C++ 13.3.3.2p3).
if (ICS1.UserDefined.ConversionFunction ==
ICS2.UserDefined.ConversionFunction)
return CompareStandardConversionSequences(ICS1.UserDefined.After,
ICS2.UserDefined.After);
}
return ImplicitConversionSequence::Indistinguishable;
}
/// CompareStandardConversionSequences - Compare two standard
/// conversion sequences to determine whether one is better than the
/// other or if they are indistinguishable (C++ 13.3.3.2p3).
ImplicitConversionSequence::CompareKind
Sema::CompareStandardConversionSequences(const StandardConversionSequence& SCS1,
const StandardConversionSequence& SCS2)
{
// Standard conversion sequence S1 is a better conversion sequence
// than standard conversion sequence S2 if (C++ 13.3.3.2p3):
// -- S1 is a proper subsequence of S2 (comparing the conversion
// sequences in the canonical form defined by 13.3.3.1.1,
// excluding any Lvalue Transformation; the identity conversion
// sequence is considered to be a subsequence of any
// non-identity conversion sequence) or, if not that,
if (SCS1.Second == SCS2.Second && SCS1.Third == SCS2.Third)
// Neither is a proper subsequence of the other. Do nothing.
;
else if ((SCS1.Second == ICK_Identity && SCS1.Third == SCS2.Third) ||
(SCS1.Third == ICK_Identity && SCS1.Second == SCS2.Second) ||
(SCS1.Second == ICK_Identity &&
SCS1.Third == ICK_Identity))
// SCS1 is a proper subsequence of SCS2.
return ImplicitConversionSequence::Better;
else if ((SCS2.Second == ICK_Identity && SCS2.Third == SCS1.Third) ||
(SCS2.Third == ICK_Identity && SCS2.Second == SCS1.Second) ||
(SCS2.Second == ICK_Identity &&
SCS2.Third == ICK_Identity))
// SCS2 is a proper subsequence of SCS1.
return ImplicitConversionSequence::Worse;
// -- the rank of S1 is better than the rank of S2 (by the rules
// defined below), or, if not that,
ImplicitConversionRank Rank1 = SCS1.getRank();
ImplicitConversionRank Rank2 = SCS2.getRank();
if (Rank1 < Rank2)
return ImplicitConversionSequence::Better;
else if (Rank2 < Rank1)
return ImplicitConversionSequence::Worse;
// (C++ 13.3.3.2p4): Two conversion sequences with the same rank
// are indistinguishable unless one of the following rules
// applies:
// A conversion that is not a conversion of a pointer, or
// pointer to member, to bool is better than another conversion
// that is such a conversion.
if (SCS1.isPointerConversionToBool() != SCS2.isPointerConversionToBool())
return SCS2.isPointerConversionToBool()
? ImplicitConversionSequence::Better
: ImplicitConversionSequence::Worse;
// C++ [over.ics.rank]p4b2:
//
// If class B is derived directly or indirectly from class A,
// conversion of B* to A* is better than conversion of B* to
// void*, and conversion of A* to void* is better than conversion
// of B* to void*.
bool SCS1ConvertsToVoid
= SCS1.isPointerConversionToVoidPointer(Context);
bool SCS2ConvertsToVoid
= SCS2.isPointerConversionToVoidPointer(Context);
if (SCS1ConvertsToVoid != SCS2ConvertsToVoid) {
// Exactly one of the conversion sequences is a conversion to
// a void pointer; it's the worse conversion.
return SCS2ConvertsToVoid ? ImplicitConversionSequence::Better
: ImplicitConversionSequence::Worse;
} else if (!SCS1ConvertsToVoid && !SCS2ConvertsToVoid) {
// Neither conversion sequence converts to a void pointer; compare
// their derived-to-base conversions.
if (ImplicitConversionSequence::CompareKind DerivedCK
= CompareDerivedToBaseConversions(SCS1, SCS2))
return DerivedCK;
} else if (SCS1ConvertsToVoid && SCS2ConvertsToVoid) {
// Both conversion sequences are conversions to void
// pointers. Compare the source types to determine if there's an
// inheritance relationship in their sources.
QualType FromType1 = QualType::getFromOpaquePtr(SCS1.FromTypePtr);
QualType FromType2 = QualType::getFromOpaquePtr(SCS2.FromTypePtr);
// Adjust the types we're converting from via the array-to-pointer
// conversion, if we need to.
if (SCS1.First == ICK_Array_To_Pointer)
FromType1 = Context.getArrayDecayedType(FromType1);
if (SCS2.First == ICK_Array_To_Pointer)
FromType2 = Context.getArrayDecayedType(FromType2);
QualType FromPointee1
= FromType1->getAsPointerType()->getPointeeType().getUnqualifiedType();
QualType FromPointee2
= FromType2->getAsPointerType()->getPointeeType().getUnqualifiedType();
if (IsDerivedFrom(FromPointee2, FromPointee1))
return ImplicitConversionSequence::Better;
else if (IsDerivedFrom(FromPointee1, FromPointee2))
return ImplicitConversionSequence::Worse;
}
// Compare based on qualification conversions (C++ 13.3.3.2p3,
// bullet 3).
if (ImplicitConversionSequence::CompareKind QualCK
= CompareQualificationConversions(SCS1, SCS2))
return QualCK;
// C++ [over.ics.rank]p3b4:
// -- S1 and S2 are reference bindings (8.5.3), and the types to
// which the references refer are the same type except for
// top-level cv-qualifiers, and the type to which the reference
// initialized by S2 refers is more cv-qualified than the type
// to which the reference initialized by S1 refers.
if (SCS1.ReferenceBinding && SCS2.ReferenceBinding) {
QualType T1 = QualType::getFromOpaquePtr(SCS1.ToTypePtr);
QualType T2 = QualType::getFromOpaquePtr(SCS2.ToTypePtr);
T1 = Context.getCanonicalType(T1);
T2 = Context.getCanonicalType(T2);
if (T1.getUnqualifiedType() == T2.getUnqualifiedType()) {
if (T2.isMoreQualifiedThan(T1))
return ImplicitConversionSequence::Better;
else if (T1.isMoreQualifiedThan(T2))
return ImplicitConversionSequence::Worse;
}
}
return ImplicitConversionSequence::Indistinguishable;
}
/// CompareQualificationConversions - Compares two standard conversion
/// sequences to determine whether they can be ranked based on their
/// qualification conversions (C++ 13.3.3.2p3 bullet 3).
ImplicitConversionSequence::CompareKind
Sema::CompareQualificationConversions(const StandardConversionSequence& SCS1,
const StandardConversionSequence& SCS2)
{
// C++ 13.3.3.2p3:
// -- S1 and S2 differ only in their qualification conversion and
// yield similar types T1 and T2 (C++ 4.4), respectively, and the
// cv-qualification signature of type T1 is a proper subset of
// the cv-qualification signature of type T2, and S1 is not the
// deprecated string literal array-to-pointer conversion (4.2).
if (SCS1.First != SCS2.First || SCS1.Second != SCS2.Second ||
SCS1.Third != SCS2.Third || SCS1.Third != ICK_Qualification)
return ImplicitConversionSequence::Indistinguishable;
// FIXME: the example in the standard doesn't use a qualification
// conversion (!)
QualType T1 = QualType::getFromOpaquePtr(SCS1.ToTypePtr);
QualType T2 = QualType::getFromOpaquePtr(SCS2.ToTypePtr);
T1 = Context.getCanonicalType(T1);
T2 = Context.getCanonicalType(T2);
// If the types are the same, we won't learn anything by unwrapped
// them.
if (T1.getUnqualifiedType() == T2.getUnqualifiedType())
return ImplicitConversionSequence::Indistinguishable;
ImplicitConversionSequence::CompareKind Result
= ImplicitConversionSequence::Indistinguishable;
while (UnwrapSimilarPointerTypes(T1, T2)) {
// Within each iteration of the loop, we check the qualifiers to
// determine if this still looks like a qualification
// conversion. Then, if all is well, we unwrap one more level of
// pointers or pointers-to-members and do it all again
// until there are no more pointers or pointers-to-members left
// to unwrap. This essentially mimics what
// IsQualificationConversion does, but here we're checking for a
// strict subset of qualifiers.
if (T1.getCVRQualifiers() == T2.getCVRQualifiers())
// The qualifiers are the same, so this doesn't tell us anything
// about how the sequences rank.
;
else if (T2.isMoreQualifiedThan(T1)) {
// T1 has fewer qualifiers, so it could be the better sequence.
if (Result == ImplicitConversionSequence::Worse)
// Neither has qualifiers that are a subset of the other's
// qualifiers.
return ImplicitConversionSequence::Indistinguishable;
Result = ImplicitConversionSequence::Better;
} else if (T1.isMoreQualifiedThan(T2)) {
// T2 has fewer qualifiers, so it could be the better sequence.
if (Result == ImplicitConversionSequence::Better)
// Neither has qualifiers that are a subset of the other's
// qualifiers.
return ImplicitConversionSequence::Indistinguishable;
Result = ImplicitConversionSequence::Worse;
} else {
// Qualifiers are disjoint.
return ImplicitConversionSequence::Indistinguishable;
}
// If the types after this point are equivalent, we're done.
if (T1.getUnqualifiedType() == T2.getUnqualifiedType())
break;
}
// Check that the winning standard conversion sequence isn't using
// the deprecated string literal array to pointer conversion.
switch (Result) {
case ImplicitConversionSequence::Better:
if (SCS1.Deprecated)
Result = ImplicitConversionSequence::Indistinguishable;
break;
case ImplicitConversionSequence::Indistinguishable:
break;
case ImplicitConversionSequence::Worse:
if (SCS2.Deprecated)
Result = ImplicitConversionSequence::Indistinguishable;
break;
}
return Result;
}
/// CompareDerivedToBaseConversions - Compares two standard conversion
/// sequences to determine whether they can be ranked based on their
/// various kinds of derived-to-base conversions (C++ [over.ics.rank]p4b3).
ImplicitConversionSequence::CompareKind
Sema::CompareDerivedToBaseConversions(const StandardConversionSequence& SCS1,
const StandardConversionSequence& SCS2) {
QualType FromType1 = QualType::getFromOpaquePtr(SCS1.FromTypePtr);
QualType ToType1 = QualType::getFromOpaquePtr(SCS1.ToTypePtr);
QualType FromType2 = QualType::getFromOpaquePtr(SCS2.FromTypePtr);
QualType ToType2 = QualType::getFromOpaquePtr(SCS2.ToTypePtr);
// Adjust the types we're converting from via the array-to-pointer
// conversion, if we need to.
if (SCS1.First == ICK_Array_To_Pointer)
FromType1 = Context.getArrayDecayedType(FromType1);
if (SCS2.First == ICK_Array_To_Pointer)
FromType2 = Context.getArrayDecayedType(FromType2);
// Canonicalize all of the types.
FromType1 = Context.getCanonicalType(FromType1);
ToType1 = Context.getCanonicalType(ToType1);
FromType2 = Context.getCanonicalType(FromType2);
ToType2 = Context.getCanonicalType(ToType2);
// C++ [over.ics.rank]p4b3:
//
// If class B is derived directly or indirectly from class A and
// class C is derived directly or indirectly from B,
// Compare based on pointer conversions.
if (SCS1.Second == ICK_Pointer_Conversion &&
SCS2.Second == ICK_Pointer_Conversion) {
QualType FromPointee1
= FromType1->getAsPointerType()->getPointeeType().getUnqualifiedType();
QualType ToPointee1
= ToType1->getAsPointerType()->getPointeeType().getUnqualifiedType();
QualType FromPointee2
= FromType2->getAsPointerType()->getPointeeType().getUnqualifiedType();
QualType ToPointee2
= ToType2->getAsPointerType()->getPointeeType().getUnqualifiedType();
// -- conversion of C* to B* is better than conversion of C* to A*,
if (FromPointee1 == FromPointee2 && ToPointee1 != ToPointee2) {
if (IsDerivedFrom(ToPointee1, ToPointee2))
return ImplicitConversionSequence::Better;
else if (IsDerivedFrom(ToPointee2, ToPointee1))
return ImplicitConversionSequence::Worse;
}
// -- conversion of B* to A* is better than conversion of C* to A*,
if (FromPointee1 != FromPointee2 && ToPointee1 == ToPointee2) {
if (IsDerivedFrom(FromPointee2, FromPointee1))
return ImplicitConversionSequence::Better;
else if (IsDerivedFrom(FromPointee1, FromPointee2))
return ImplicitConversionSequence::Worse;
}
}
// Compare based on reference bindings.
if (SCS1.ReferenceBinding && SCS2.ReferenceBinding &&
SCS1.Second == ICK_Derived_To_Base) {
// -- binding of an expression of type C to a reference of type
// B& is better than binding an expression of type C to a
// reference of type A&,
if (FromType1.getUnqualifiedType() == FromType2.getUnqualifiedType() &&
ToType1.getUnqualifiedType() != ToType2.getUnqualifiedType()) {
if (IsDerivedFrom(ToType1, ToType2))
return ImplicitConversionSequence::Better;
else if (IsDerivedFrom(ToType2, ToType1))
return ImplicitConversionSequence::Worse;
}
// -- binding of an expression of type B to a reference of type
// A& is better than binding an expression of type C to a
// reference of type A&,
if (FromType1.getUnqualifiedType() != FromType2.getUnqualifiedType() &&
ToType1.getUnqualifiedType() == ToType2.getUnqualifiedType()) {
if (IsDerivedFrom(FromType2, FromType1))
return ImplicitConversionSequence::Better;
else if (IsDerivedFrom(FromType1, FromType2))
return ImplicitConversionSequence::Worse;
}
}
// FIXME: conversion of A::* to B::* is better than conversion of
// A::* to C::*,
// FIXME: conversion of B::* to C::* is better than conversion of
// A::* to C::*, and
if (SCS1.CopyConstructor && SCS2.CopyConstructor &&
SCS1.Second == ICK_Derived_To_Base) {
// -- conversion of C to B is better than conversion of C to A,
if (FromType1.getUnqualifiedType() == FromType2.getUnqualifiedType() &&
ToType1.getUnqualifiedType() != ToType2.getUnqualifiedType()) {
if (IsDerivedFrom(ToType1, ToType2))
return ImplicitConversionSequence::Better;
else if (IsDerivedFrom(ToType2, ToType1))
return ImplicitConversionSequence::Worse;
}
// -- conversion of B to A is better than conversion of C to A.
if (FromType1.getUnqualifiedType() != FromType2.getUnqualifiedType() &&
ToType1.getUnqualifiedType() == ToType2.getUnqualifiedType()) {
if (IsDerivedFrom(FromType2, FromType1))
return ImplicitConversionSequence::Better;
else if (IsDerivedFrom(FromType1, FromType2))
return ImplicitConversionSequence::Worse;
}
}
return ImplicitConversionSequence::Indistinguishable;
}
/// TryCopyInitialization - Try to copy-initialize a value of type
/// ToType from the expression From. Return the implicit conversion
/// sequence required to pass this argument, which may be a bad
/// conversion sequence (meaning that the argument cannot be passed to
/// a parameter of this type). If @p SuppressUserConversions, then we
/// do not permit any user-defined conversion sequences.
ImplicitConversionSequence
Sema::TryCopyInitialization(Expr *From, QualType ToType,
bool SuppressUserConversions) {
if (!getLangOptions().CPlusPlus) {
// In C, copy initialization is the same as performing an assignment.
AssignConvertType ConvTy =
CheckSingleAssignmentConstraints(ToType, From);
ImplicitConversionSequence ICS;
if (getLangOptions().NoExtensions? ConvTy != Compatible
: ConvTy == Incompatible)
ICS.ConversionKind = ImplicitConversionSequence::BadConversion;
else
ICS.ConversionKind = ImplicitConversionSequence::StandardConversion;
return ICS;
} else if (ToType->isReferenceType()) {
ImplicitConversionSequence ICS;
CheckReferenceInit(From, ToType, &ICS, SuppressUserConversions);
return ICS;
} else {
return TryImplicitConversion(From, ToType, SuppressUserConversions);
}
}
/// PerformArgumentPassing - Pass the argument Arg into a parameter of
/// type ToType. Returns true (and emits a diagnostic) if there was
/// an error, returns false if the initialization succeeded.
bool Sema::PerformCopyInitialization(Expr *&From, QualType ToType,
const char* Flavor) {
if (!getLangOptions().CPlusPlus) {
// In C, argument passing is the same as performing an assignment.
QualType FromType = From->getType();
AssignConvertType ConvTy =
CheckSingleAssignmentConstraints(ToType, From);
return DiagnoseAssignmentResult(ConvTy, From->getLocStart(), ToType,
FromType, From, Flavor);
} else if (ToType->isReferenceType()) {
return CheckReferenceInit(From, ToType);
} else {
if (PerformImplicitConversion(From, ToType))
return Diag(From->getSourceRange().getBegin(),
diag::err_typecheck_convert_incompatible,
ToType.getAsString(), From->getType().getAsString(),
Flavor,
From->getSourceRange());
else
return false;
}
}
/// AddOverloadCandidate - Adds the given function to the set of
/// candidate functions, using the given function call arguments. If
/// @p SuppressUserConversions, then don't allow user-defined
/// conversions via constructors or conversion operators.
void
Sema::AddOverloadCandidate(FunctionDecl *Function,
Expr **Args, unsigned NumArgs,
OverloadCandidateSet& CandidateSet,
bool SuppressUserConversions)
{
const FunctionTypeProto* Proto
= dyn_cast<FunctionTypeProto>(Function->getType()->getAsFunctionType());
assert(Proto && "Functions without a prototype cannot be overloaded");
assert(!isa<CXXConversionDecl>(Function) &&
"Use AddConversionCandidate for conversion functions");
// Add this candidate
CandidateSet.push_back(OverloadCandidate());
OverloadCandidate& Candidate = CandidateSet.back();
Candidate.Function = Function;
unsigned NumArgsInProto = Proto->getNumArgs();
// (C++ 13.3.2p2): A candidate function having fewer than m
// parameters is viable only if it has an ellipsis in its parameter
// list (8.3.5).
if (NumArgs > NumArgsInProto && !Proto->isVariadic()) {
Candidate.Viable = false;
return;
}
// (C++ 13.3.2p2): A candidate function having more than m parameters
// is viable only if the (m+1)st parameter has a default argument
// (8.3.6). For the purposes of overload resolution, the
// parameter list is truncated on the right, so that there are
// exactly m parameters.
unsigned MinRequiredArgs = Function->getMinRequiredArguments();
if (NumArgs < MinRequiredArgs) {
// Not enough arguments.
Candidate.Viable = false;
return;
}
// Determine the implicit conversion sequences for each of the
// arguments.
Candidate.Viable = true;
Candidate.Conversions.resize(NumArgs);
for (unsigned ArgIdx = 0; ArgIdx < NumArgs; ++ArgIdx) {
if (ArgIdx < NumArgsInProto) {
// (C++ 13.3.2p3): for F to be a viable function, there shall
// exist for each argument an implicit conversion sequence
// (13.3.3.1) that converts that argument to the corresponding
// parameter of F.
QualType ParamType = Proto->getArgType(ArgIdx);
Candidate.Conversions[ArgIdx]
= TryCopyInitialization(Args[ArgIdx], ParamType,
SuppressUserConversions);
if (Candidate.Conversions[ArgIdx].ConversionKind
== ImplicitConversionSequence::BadConversion)
Candidate.Viable = false;
} else {
// (C++ 13.3.2p2): For the purposes of overload resolution, any
// argument for which there is no corresponding parameter is
// considered to ""match the ellipsis" (C+ 13.3.3.1.3).
Candidate.Conversions[ArgIdx].ConversionKind
= ImplicitConversionSequence::EllipsisConversion;
}
}
}
/// AddConversionCandidate - Add a C++ conversion function as a
/// candidate in the candidate set (C++ [over.match.conv],
/// C++ [over.match.copy]). From is the expression we're converting from,
/// and ToType is the type that we're eventually trying to convert to
/// (which may or may not be the same type as the type that the
/// conversion function produces).
void
Sema::AddConversionCandidate(CXXConversionDecl *Conversion,
Expr *From, QualType ToType,
OverloadCandidateSet& CandidateSet) {
// Add this candidate
CandidateSet.push_back(OverloadCandidate());
OverloadCandidate& Candidate = CandidateSet.back();
Candidate.Function = Conversion;
Candidate.FinalConversion.setAsIdentityConversion();
Candidate.FinalConversion.FromTypePtr
= Conversion->getConversionType().getAsOpaquePtr();
Candidate.FinalConversion.ToTypePtr = ToType.getAsOpaquePtr();
// Determine the implicit conversion sequences for each of the
// arguments.
Candidate.Viable = true;
Candidate.Conversions.resize(1);
// FIXME: We need to follow the rules for the implicit object
// parameter.
QualType ImplicitObjectType
= Context.getTypeDeclType(Conversion->getParent());
ImplicitObjectType
= ImplicitObjectType.getQualifiedType(Conversion->getTypeQualifiers());
ImplicitObjectType = Context.getReferenceType(ImplicitObjectType);
Candidate.Conversions[0] = TryCopyInitialization(From, ImplicitObjectType,
true);
if (Candidate.Conversions[0].ConversionKind
== ImplicitConversionSequence::BadConversion) {
Candidate.Viable = false;
return;
}
// To determine what the conversion from the result of calling the
// conversion function to the type we're eventually trying to
// convert to (ToType), we need to synthesize a call to the
// conversion function and attempt copy initialization from it. This
// makes sure that we get the right semantics with respect to
// lvalues/rvalues and the type. Fortunately, we can allocate this
// call on the stack and we don't need its arguments to be
// well-formed.
DeclRefExpr ConversionRef(Conversion, Conversion->getType(),
SourceLocation());
ImplicitCastExpr ConversionFn(Context.getPointerType(Conversion->getType()),
&ConversionRef);
CallExpr Call(&ConversionFn, 0, 0,
Conversion->getConversionType().getNonReferenceType(),
SourceLocation());
ImplicitConversionSequence ICS = TryCopyInitialization(&Call, ToType, true);
switch (ICS.ConversionKind) {
case ImplicitConversionSequence::StandardConversion:
Candidate.FinalConversion = ICS.Standard;
break;
case ImplicitConversionSequence::BadConversion:
Candidate.Viable = false;
break;
default:
assert(false &&
"Can only end up with a standard conversion sequence or failure");
}
}
/// AddOverloadCandidates - Add all of the function overloads in Ovl
/// to the candidate set.
void
Sema::AddOverloadCandidates(const OverloadedFunctionDecl *Ovl,
Expr **Args, unsigned NumArgs,
OverloadCandidateSet& CandidateSet,
bool SuppressUserConversions)
{
for (OverloadedFunctionDecl::function_const_iterator Func
= Ovl->function_begin();
Func != Ovl->function_end(); ++Func)
AddOverloadCandidate(*Func, Args, NumArgs, CandidateSet,
SuppressUserConversions);
}
/// isBetterOverloadCandidate - Determines whether the first overload
/// candidate is a better candidate than the second (C++ 13.3.3p1).
bool
Sema::isBetterOverloadCandidate(const OverloadCandidate& Cand1,
const OverloadCandidate& Cand2)
{
// Define viable functions to be better candidates than non-viable
// functions.
if (!Cand2.Viable)
return Cand1.Viable;
else if (!Cand1.Viable)
return false;
// FIXME: Deal with the implicit object parameter for static member
// functions. (C++ 13.3.3p1).
// (C++ 13.3.3p1): a viable function F1 is defined to be a better
// function than another viable function F2 if for all arguments i,
// ICSi(F1) is not a worse conversion sequence than ICSi(F2), and
// then...
unsigned NumArgs = Cand1.Conversions.size();
assert(Cand2.Conversions.size() == NumArgs && "Overload candidate mismatch");
bool HasBetterConversion = false;
for (unsigned ArgIdx = 0; ArgIdx < NumArgs; ++ArgIdx) {
switch (CompareImplicitConversionSequences(Cand1.Conversions[ArgIdx],
Cand2.Conversions[ArgIdx])) {
case ImplicitConversionSequence::Better:
// Cand1 has a better conversion sequence.
HasBetterConversion = true;
break;
case ImplicitConversionSequence::Worse:
// Cand1 can't be better than Cand2.
return false;
case ImplicitConversionSequence::Indistinguishable:
// Do nothing.
break;
}
}
if (HasBetterConversion)
return true;
// FIXME: Several other bullets in (C++ 13.3.3p1) need to be implemented.
// C++ [over.match.best]p1b4:
//
// -- the context is an initialization by user-defined conversion
// (see 8.5, 13.3.1.5) and the standard conversion sequence
// from the return type of F1 to the destination type (i.e.,
// the type of the entity being initialized) is a better
// conversion sequence than the standard conversion sequence
// from the return type of F2 to the destination type.
if (isa<CXXConversionDecl>(Cand1.Function) &&
isa<CXXConversionDecl>(Cand2.Function)) {
switch (CompareStandardConversionSequences(Cand1.FinalConversion,
Cand2.FinalConversion)) {
case ImplicitConversionSequence::Better:
// Cand1 has a better conversion sequence.
return true;
case ImplicitConversionSequence::Worse:
// Cand1 can't be better than Cand2.
return false;
case ImplicitConversionSequence::Indistinguishable:
// Do nothing
break;
}
}
return false;
}
/// BestViableFunction - Computes the best viable function (C++ 13.3.3)
/// within an overload candidate set. If overloading is successful,
/// the result will be OR_Success and Best will be set to point to the
/// best viable function within the candidate set. Otherwise, one of
/// several kinds of errors will be returned; see
/// Sema::OverloadingResult.
Sema::OverloadingResult
Sema::BestViableFunction(OverloadCandidateSet& CandidateSet,
OverloadCandidateSet::iterator& Best)
{
// Find the best viable function.
Best = CandidateSet.end();
for (OverloadCandidateSet::iterator Cand = CandidateSet.begin();
Cand != CandidateSet.end(); ++Cand) {
if (Cand->Viable) {
if (Best == CandidateSet.end() || isBetterOverloadCandidate(*Cand, *Best))
Best = Cand;
}
}
// If we didn't find any viable functions, abort.
if (Best == CandidateSet.end())
return OR_No_Viable_Function;
// Make sure that this function is better than every other viable
// function. If not, we have an ambiguity.
for (OverloadCandidateSet::iterator Cand = CandidateSet.begin();
Cand != CandidateSet.end(); ++Cand) {
if (Cand->Viable &&
Cand != Best &&
!isBetterOverloadCandidate(*Best, *Cand))
return OR_Ambiguous;
}
// Best is the best viable function.
return OR_Success;
}
/// PrintOverloadCandidates - When overload resolution fails, prints
/// diagnostic messages containing the candidates in the candidate
/// set. If OnlyViable is true, only viable candidates will be printed.
void
Sema::PrintOverloadCandidates(OverloadCandidateSet& CandidateSet,
bool OnlyViable)
{
OverloadCandidateSet::iterator Cand = CandidateSet.begin(),
LastCand = CandidateSet.end();
for (; Cand != LastCand; ++Cand) {
if (Cand->Viable ||!OnlyViable)
Diag(Cand->Function->getLocation(), diag::err_ovl_candidate);
}
}
/// ResolveAddressOfOverloadedFunction - Try to resolve the address of
/// an overloaded function (C++ [over.over]), where @p From is an
/// expression with overloaded function type and @p ToType is the type
/// we're trying to resolve to. For example:
///
/// @code
/// int f(double);
/// int f(int);
///
/// int (*pfd)(double) = f; // selects f(double)
/// @endcode
///
/// This routine returns the resulting FunctionDecl if it could be
/// resolved, and NULL otherwise. When @p Complain is true, this
/// routine will emit diagnostics if there is an error.
FunctionDecl *
Sema::ResolveAddressOfOverloadedFunction(Expr *From, QualType ToType,
bool Complain) {
QualType FunctionType = ToType;
if (const PointerLikeType *ToTypePtr = ToType->getAsPointerLikeType())
FunctionType = ToTypePtr->getPointeeType();
// We only look at pointers or references to functions.
if (!FunctionType->isFunctionType())
return 0;
// Find the actual overloaded function declaration.
OverloadedFunctionDecl *Ovl = 0;
// C++ [over.over]p1:
// [...] [Note: any redundant set of parentheses surrounding the
// overloaded function name is ignored (5.1). ]
Expr *OvlExpr = From->IgnoreParens();
// C++ [over.over]p1:
// [...] The overloaded function name can be preceded by the &
// operator.
if (UnaryOperator *UnOp = dyn_cast<UnaryOperator>(OvlExpr)) {
if (UnOp->getOpcode() == UnaryOperator::AddrOf)
OvlExpr = UnOp->getSubExpr()->IgnoreParens();
}
// Try to dig out the overloaded function.
if (DeclRefExpr *DR = dyn_cast<DeclRefExpr>(OvlExpr))
Ovl = dyn_cast<OverloadedFunctionDecl>(DR->getDecl());
// If there's no overloaded function declaration, we're done.
if (!Ovl)
return 0;
// Look through all of the overloaded functions, searching for one
// whose type matches exactly.
// FIXME: When templates or using declarations come along, we'll actually
// have to deal with duplicates, partial ordering, etc. For now, we
// can just do a simple search.
FunctionType = Context.getCanonicalType(FunctionType.getUnqualifiedType());
for (OverloadedFunctionDecl::function_iterator Fun = Ovl->function_begin();
Fun != Ovl->function_end(); ++Fun) {
// C++ [over.over]p3:
// Non-member functions and static member functions match
// targets of type “pointer-to-function”or
// “reference-to-function.”
if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(*Fun))
if (!Method->isStatic())
continue;
if (FunctionType == Context.getCanonicalType((*Fun)->getType()))
return *Fun;
}
return 0;
}
/// FixOverloadedFunctionReference - E is an expression that refers to
/// a C++ overloaded function (possibly with some parentheses and
/// perhaps a '&' around it). We have resolved the overloaded function
/// to the function declaration Fn, so patch up the expression E to
/// refer (possibly indirectly) to Fn.
void Sema::FixOverloadedFunctionReference(Expr *E, FunctionDecl *Fn) {
if (ParenExpr *PE = dyn_cast<ParenExpr>(E)) {
FixOverloadedFunctionReference(PE->getSubExpr(), Fn);
E->setType(PE->getSubExpr()->getType());
} else if (UnaryOperator *UnOp = dyn_cast<UnaryOperator>(E)) {
assert(UnOp->getOpcode() == UnaryOperator::AddrOf &&
"Can only take the address of an overloaded function");
FixOverloadedFunctionReference(UnOp->getSubExpr(), Fn);
E->setType(Context.getPointerType(E->getType()));
} else if (DeclRefExpr *DR = dyn_cast<DeclRefExpr>(E)) {
assert(isa<OverloadedFunctionDecl>(DR->getDecl()) &&
"Expected overloaded function");
DR->setDecl(Fn);
E->setType(Fn->getType());
} else {
assert(false && "Invalid reference to overloaded function");
}
}
} // end namespace clang
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