| Message ID | 20240122181153.876572-1-ppalka@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | c++: ambiguous member lookup for rewritten cands [PR113529] | expand |
On 1/22/24 13:11, Patrick Palka wrote: > Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look > OK for trunk/13? > > -- >8 -- > > Here we handle the operator expression u < v inconsistently: in a SFINAE > context (such as a requires-expression) we accept the it, and in a > non-SFINAE context we reject it with > > error: request for member 'operator<=>' is ambiguous > > as per [class.member.lookup]/6. This inconsistency is ultimately > because we neglect to propagate error_mark_node after recursing in > add_operator_candidates, fixed like so. Shouldn't we do the same with the other recursive call? Please also add return value documentation to the comment before the function. OK with those changes. Jason
On Tue, 23 Jan 2024, Jason Merrill wrote: > On 1/22/24 13:11, Patrick Palka wrote: > > Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look > > OK for trunk/13? > > > > -- >8 -- > > > > Here we handle the operator expression u < v inconsistently: in a SFINAE > > context (such as a requires-expression) we accept the it, and in a > > non-SFINAE context we reject it with > > > > error: request for member 'operator<=>' is ambiguous > > > > as per [class.member.lookup]/6. This inconsistency is ultimately > > because we neglect to propagate error_mark_node after recursing in > > add_operator_candidates, fixed like so. > > Shouldn't we do the same with the other recursive call? Oops, yes. I thought that the function is symmetric with respect to member lookup so it should suffice to check the first recursive call, but member lookup is only performed for the first argument type, and arguments are swapped for the second recursive call. > > Please also add return value documentation to the comment before the function. Will do, thanks! > > OK with those changes. > > Jason > >
diff --git a/gcc/cp/call.cc b/gcc/cp/call.cc index 1f5ff417c81..183bb8c1348 100644 --- a/gcc/cp/call.cc +++ b/gcc/cp/call.cc @@ -7007,9 +7007,14 @@ add_operator_candidates (z_candidate **candidates, { flags |= LOOKUP_REWRITTEN; if (rewrite_code != code) - /* Add rewritten candidates in same order. */ - add_operator_candidates (candidates, rewrite_code, ERROR_MARK, - arglist, lookups, flags, complain); + { + /* Add rewritten candidates in same order. */ + tree r = add_operator_candidates (candidates, rewrite_code, + ERROR_MARK, arglist, lookups, + flags, complain); + if (r == error_mark_node) + return error_mark_node; + } z_candidate *save_cand = *candidates; diff --git a/gcc/testsuite/g++.dg/cpp2a/spaceship-sfinae3.C b/gcc/testsuite/g++.dg/cpp2a/spaceship-sfinae3.C new file mode 100644 index 00000000000..ca159260ec7 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp2a/spaceship-sfinae3.C @@ -0,0 +1,22 @@ +// PR c++/113529 +// { dg-do compile { target c++20 } } + +#include <compare> + +struct A { + auto operator<=>(const A&) const = default; + bool operator<(const A&) const; +}; +struct B { + auto operator<=>(const B&) const = default; +}; +struct C : A, B { }; + + +template<class T> +void f(T u, T v) { + static_assert(!requires { u < v; }); + u < v; // { dg-error "request for member 'operator<=>' is ambiguous" } +} + +template void f(C, C);