[Bug c++/78173] Hard error subtracting pointers to incomplete type in SFINAE context

[cvs-commit at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78173

--- Comment #5 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Patrick Palka <ppa...@gcc.gnu.org>:

https://gcc.gnu.org/g:958d42abdf1a1936d290aab126cebd6bb4a52361

commit r11-5936-g958d42abdf1a1936d290aab126cebd6bb4a52361
Author: Patrick Palka <ppa...@redhat.com>
Date:   Fri Dec 11 09:40:58 2020 -0500

    c++: missing SFINAE with pointer subtraction [PR78173]

    This fixes a missed SFINAE when subtracting pointers to an incomplete
    type.

    gcc/cp/ChangeLog:

            PR c++/78173
            * typeck.c (pointer_diff): Use complete_type_or_maybe_complain
            instead of complete_type_or_else.

    gcc/testsuite/ChangeLog:

            PR c++/78173
            * g++.dg/cpp2a/concepts-pr78173.C: New test.