[Bug preprocessor/112701] wrong type inference for ternary operator with `0/0u` in preprocessing context

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112701

--- Comment #7 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Lewis Hyatt <lhyatt@gcc.gnu.org>:

https://gcc.gnu.org/g:ce52f1f7074d96c4d9ce63b1169c11087757e926

commit r14-5898-gce52f1f7074d96c4d9ce63b1169c11087757e926
Author: Lewis Hyatt <lhyatt@gmail.com>
Date:   Mon Nov 27 12:08:41 2023 -0500

    libcpp: Fix unsigned promotion for unevaluated divide by zero [PR112701]

    When libcpp encounters a divide by zero while processing a constant
    expression "x/y", it returns "x" as a fallback. The value of the fallback
is
    not normally important, since an error will be generated anyway, but if the
    expression appears in an unevaluated context, such as "0 ? 0/0u : -1", then
    there will be no error, and the fallback value will be meaningful to the
    extent that it may cause promotion from signed to unsigned of an operand
    encountered later. As the PR notes, libcpp does not do the unsigned
    promotion correctly in this case; fix it by making the fallback return
value
    unsigned as necessary.

    libcpp/ChangeLog:

            PR preprocessor/112701
            * expr.cc (num_div_op): Set unsignedp appropriately when returning
a
            stub value for divide by 0.

    gcc/testsuite/ChangeLog:

            PR preprocessor/112701
            * gcc.dg/cpp/expr.c: Add additional tests to cover divide by 0 in
an
            unevaluated context, where the unsignedness still matters.