Re: [PATCH v3 3/3] c++: note other candidates when diagnosing deletedness

[Jason Merrill <jason@redhat.com>]

On 10/27/23 15:55, 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
> 
> These notes are controlled by a new command line flag -fnote-all-cands,
> which also controls whether we note ignored candidates more generally.
> 
> gcc/ChangeLog:
> 
> 	* doc/invoke.texi (C++ Dialect Options): Document -fnote-all-cands.
> 
> gcc/c-family/ChangeLog:
> 
> 	* c.opt: Add -fnote-all-cands.
> 
> gcc/cp/ChangeLog:
> 
> 	* call.cc (print_z_candidates): Only print ignored candidates
> 	when -fnote-all-cands is set.
> 	(build_over_call): When diagnosing deletedness, call
> 	print_z_candidates if -fnote-all-cands is set.

My suggestion was also to suggest using the flag in cases where it would 
make a difference, e.g.

note: some candidates omitted, use '-fnote-all-cands' to display them

Maybe "-fdiagnostics-all-candidates"?

Jason