PR44721: Don't consider overloaded operators for built-in comparisons

when building a defaulted comparison.

As a convenient way of asking whether `x @ y` is valid and building it,
we previouly always performed overload resolution and built an
overloaded expression, which would both end up picking a builtin
operator candidate when given a non-overloadable type. But that's not
quite right, because it can result in our finding a user-declared
operator overload, which we should never do when applying operators
non-overloadable types.

Handle this more correctly: skip overload resolution when building
`x @ y` if the operands are not overloadable. But still perform overload
resolution (considering only builtin candidates) when checking validity,
as we don't have any other good way to ask whether a binary operator
expression would be valid.
This commit is contained in:
Richard Smith 2020-01-30 17:11:47 -08:00
parent d28763cad0
commit 1f3f8c369a
2 changed files with 34 additions and 7 deletions

View File

@ -7373,7 +7373,14 @@ private:
/// resolution [...]
CandidateSet.exclude(FD);
if (Args[0]->getType()->isOverloadableType())
S.LookupOverloadedBinOp(CandidateSet, OO, Fns, Args);
else {
// FIXME: We determine whether this is a valid expression by checking to
// see if there's a viable builtin operator candidate for it. That isn't
// really what the rules ask us to do, but should give the right results.
S.AddBuiltinOperatorCandidates(OO, FD->getLocation(), Args, CandidateSet);
}
Result R;
@ -7826,10 +7833,14 @@ private:
return StmtError();
OverloadedOperatorKind OO = FD->getOverloadedOperator();
ExprResult Op = S.CreateOverloadedBinOp(
Loc, BinaryOperator::getOverloadedOpcode(OO), Fns,
Obj.first.get(), Obj.second.get(), /*PerformADL=*/true,
BinaryOperatorKind Opc = BinaryOperator::getOverloadedOpcode(OO);
ExprResult Op;
if (Type->isOverloadableType())
Op = S.CreateOverloadedBinOp(Loc, Opc, Fns, Obj.first.get(),
Obj.second.get(), /*PerformADL=*/true,
/*AllowRewrittenCandidates=*/true, FD);
else
Op = S.CreateBuiltinBinOp(Loc, Opc, Obj.first.get(), Obj.second.get());
if (Op.isInvalid())
return StmtError();
@ -7869,8 +7880,12 @@ private:
llvm::APInt ZeroVal(S.Context.getIntWidth(S.Context.IntTy), 0);
Expr *Zero =
IntegerLiteral::Create(S.Context, ZeroVal, S.Context.IntTy, Loc);
ExprResult Comp = S.CreateOverloadedBinOp(Loc, BO_NE, Fns, VDRef.get(),
Zero, true, true, FD);
ExprResult Comp;
if (VDRef.get()->getType()->isOverloadableType())
Comp = S.CreateOverloadedBinOp(Loc, BO_NE, Fns, VDRef.get(), Zero, true,
true, FD);
else
Comp = S.CreateBuiltinBinOp(Loc, BO_NE, VDRef.get(), Zero);
if (Comp.isInvalid())
return StmtError();
Sema::ConditionResult Cond = S.ActOnCondition(

View File

@ -190,3 +190,15 @@ bool operator<(const G&, const G&);
bool operator<=(const G&, const G&);
bool operator>(const G&, const G&);
bool operator>=(const G&, const G&);
namespace PR44721 {
template <typename T> bool operator==(T const &, T const &) { return true; }
template <typename T, typename U> bool operator!=(T const &, U const &) { return true; }
template <typename T> int operator<=>(T const &, T const &) { return 0; }
struct S {
friend bool operator==(const S &, const S &) = default;
friend bool operator<=>(const S &, const S &) = default;
int x;
};
}