[Bug preprocessor/112701] New: wrong type inference for ternary operator in preprocessing context

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

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

            Bug ID: 112701
           Summary: wrong type inference for ternary operator in
                    preprocessing context
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: preprocessor
          Assignee: unassigned at gcc dot gnu.org
          Reporter: amonakov at gcc dot gnu.org
  Target Milestone: ---

In the following snippet, the result of the ternary operator is (-1, cast to an
unsigned type), so the comparison yields false, and both conditional inclusions
must come out empty:

#if (0 ? 0u : -1) < 0
int foo = (0 ? 0u : -1) < 0;
#endif

#if (0 ? 0/0u : -1) < 0
int bar = (0 ? 0/0u : -1) < 0;
#endif

However, GCC emits:

bar:
        .zero   4

So clearly the evaluation of the second expression is inconsistent between
preprocessing context (where it incorrectly yields 1) vs. initializer context
(where it is zero as it should be, as seen from the resulting asm).