[Bug c++/109159] [10/11/12/13 Regression] explicit constructor is used in copy-initialization

["cvs-commit at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109159

--- Comment #4 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The trunk branch has been updated by Marek Polacek <mpolacek@gcc.gnu.org>:

https://gcc.gnu.org/g:a226590fefb35ed66adf73d85cefe49048a78ab8

commit r13-6765-ga226590fefb35ed66adf73d85cefe49048a78ab8
Author: Marek Polacek <polacek@redhat.com>
Date:   Fri Mar 17 18:25:13 2023 -0400

    c++: explicit ctor and list-initialization [PR109159]

    When I implemented explicit(bool) in r9-3735, I added this code to
    add_template_candidate_real:
    +  /* Now the explicit specifier might have been deduced; check if this
    +     declaration is explicit.  If it is and we're ignoring non-converting
    +     constructors, don't add this function to the set of candidates.  */
    +  if ((flags & LOOKUP_ONLYCONVERTING) && DECL_NONCONVERTING_P (fn))
    +    return NULL;
    but as this test demonstrates, that's incorrect when we're initializing
    from a {}: for list-initialization we consider explicit constructors and
    complain if one is chosen.

            PR c++/109159

    gcc/cp/ChangeLog:

            * call.cc (add_template_candidate_real): Add explicit decls to the
            set of candidates when the initializer is a braced-init-list.

    libstdc++-v3/ChangeLog:

            * testsuite/20_util/pair/cons/explicit_construct.cc: Adjust
dg-error.
            * testsuite/20_util/tuple/cons/explicit_construct.cc: Likewise.
            * testsuite/23_containers/span/explicit.cc: Likewise.

    gcc/testsuite/ChangeLog:

            * g++.dg/cpp0x/explicit16.C: New test.