[Bug c++/104392] Unexpected Narrowing Warning when spaceship comparison of unsigned bit field

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104392

--- Comment #3 from GCC 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:52d71b6b1f0f465a6cf064f61b22fc99453ec132

commit r15-1758-g52d71b6b1f0f465a6cf064f61b22fc99453ec132
Author: Marek Polacek <polacek@redhat.com>
Date:   Fri Jun 28 17:51:19 2024 -0400

    c++: DR2627, Bit-fields and narrowing conversions [PR94058]

    This DR (https://cplusplus.github.io/CWG/issues/2627.html) says that
    even if we are converting from an integer type or unscoped enumeration type
    to an integer type that cannot represent all the values of the original
    type, it's not narrowing if "the source is a bit-field whose width w is
    less than that of its type (or, for an enumeration type, its underlying
    type) and the target type can represent all the values of a hypothetical
    extended integer type with width w and with the same signedness as the
    original type".

            DR 2627
            PR c++/94058
            PR c++/104392

    gcc/cp/ChangeLog:

            * typeck2.cc (check_narrowing): Don't warn if the conversion isn't
            narrowing as per DR 2627.

    gcc/testsuite/ChangeLog:

            * g++.dg/DRs/dr2627.C: New test.
            * g++.dg/cpp0x/Wnarrowing22.C: New test.
            * g++.dg/cpp2a/spaceship-narrowing1.C: New test.
            * g++.dg/cpp2a/spaceship-narrowing2.C: New test.