Message ID | 20231023235154.2971561-3-ppalka@redhat.com |
---|---|
State | New |
Headers | show |
Series | [v2,1/3] c++: sort candidates according to viability | expand |
On 10/23/23 19:51, Patrick Palka wrote: > With the previous two patches in place, we can now extend our > deletedness diagnostic to note the other considered candidates, e.g.: > > deleted16.C: In function 'int main()': > deleted16.C:10:4: error: use of deleted function 'void f(int)' > 10 | f(0); > | ~^~~ > deleted16.C:5:6: note: declared here > 5 | void f(int) = delete; > | ^ > deleted16.C:5:6: note: candidate: 'void f(int)' (deleted) > deleted16.C:6:6: note: candidate: 'void f(...)' > 6 | void f(...); > | ^ > deleted16.C:7:6: note: candidate: 'void f(int, int)' > 7 | void f(int, int); > | ^ > deleted16.C:7:6: note: candidate expects 2 arguments, 1 provided > > For now, these these notes are disabled when a deleted special member > function is selected because it introduces a lot of new "cannot bind > reference" errors in the testsuite when noting non-viable candidates, > e.g. in cpp0x/initlist-opt1.C we would need to expect an error when > noting unviability of A(A&&). (It'd be nice if we could downgrade such > errors into notes when noting candidates...) What about my suggestion to make printing the other candidates an opt-in, with the normal output just suggesting the use of that option for more information, like -ftemplate-backtrace-limit? Jason
diff --git a/gcc/cp/call.cc b/gcc/cp/call.cc index 3212d5268e0..1313d6516bd 100644 --- a/gcc/cp/call.cc +++ b/gcc/cp/call.cc @@ -9932,7 +9932,15 @@ build_over_call (struct z_candidate *cand, int flags, tsubst_flags_t complain) if (DECL_DELETED_FN (fn)) { if (complain & tf_error) - mark_used (fn); + { + mark_used (fn); + /* Note the other candidates we considered unless we selected a + special member function since the mismatch reasons for other + candidates are usually uninteresting, e.g. rvalue vs lvalue + reference binding . */ + if (cand->next && !special_memfn_p (fn)) + print_z_candidates (input_location, cand, /*only_viable_p=*/false); + } return error_mark_node; } diff --git a/gcc/testsuite/g++.dg/cpp0x/deleted16.C b/gcc/testsuite/g++.dg/cpp0x/deleted16.C new file mode 100644 index 00000000000..55acbfd9188 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp0x/deleted16.C @@ -0,0 +1,24 @@ +// Verify we note other candidates when a deleted function is +// selected by overload resolution. +// { dg-do compile { target c++11 } } + +void f(int) = delete; // { dg-message "declared here|candidate" } +void f(...); // { dg-message "candidate" } +void f(int, int); // { dg-message "candidate" } + +// An example where the perfect candidate optimization causes us +// to ignore function templates. +void g(int) = delete; // { dg-message "declared here|candidate" } +template<class T> void g(T); // { dg-message "candidate" } + +// An example where we have a strictly viable candidate and +// an incompletely considered bad candidate. +template<class T> void h(T, T) = delete; // { dg-message "declared here|candidate" } +void h(int*, int) = delete; // { dg-message "candidate" } + +int main() { + f(0); // { dg-error "deleted" } + g(0); // { dg-error "deleted" } + h(1, 1); // { dg-error "deleted" } + // { dg-error "invalid conversion" "" { target *-*-* } .-1 } when noting 2nd cand +}