commit 79c5a09f959dc63824bd005522a072424f16d89d
author Patrick Palka <ppalka@redhat.com> Fri Jun 28 19:45:21 2024 -0400
committer Patrick Palka <ppalka@redhat.com> Wed Jul 17 15:02:24 2024 -0400
tree 2e2c29099ec8e8b4703d673418460e78969ca9c1
parent 3a963d441a68797956a5f67dcb351b2dbd4ac1d0

c++: bad 'this' conversion for nullary memfn [PR106760]

Here we notice the 'this' conversion for the call f<void>() is bad, so
we correctly defer deduction for the template candidate, but we end up
never adding it to 'bad_cands' since missing_conversion_p for it returns
false (its only argument is 'this' which has already been determined to
be bad).  This is not a huge deal, but it causes us to longer accept the
call with -fpermissive in release builds, and a tree check ICE in checking
builds.

So if we have a non-strictly viable template candidate that has not been
instantiated, then we need to add it to 'bad_cands' even if no argument
conversion is missing.

	PR c++/106760

gcc/cp/ChangeLog:

	* call.cc (add_candidates): Relax test for adding a candidate
	to 'bad_cands' to also accept an uninstantiated template candidate
	that has no missing conversions.

gcc/testsuite/ChangeLog:

	* g++.dg/ext/conv3.C: New test.

Reviewed-by: Jason Merrill <jason@redhat.com>
(cherry picked from commit 50073ffae0a9b8feb9b36fdafdebd9885f6d7dc8)