[Bug c/85995] New: GCC defines __STDC__ and __STDC_VERSION__ even when used with options that break C conformance

[vincent-gcc at vinc17 dot net]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85995

            Bug ID: 85995
           Summary: GCC defines __STDC__ and __STDC_VERSION__ even when
                    used with options that break C conformance
           Product: gcc
           Version: 9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: vincent-gcc at vinc17 dot net
  Target Milestone: ---

According to "gcc -dM -E -xc /dev/null" with some additional options, GCC
currently defines __STDC__ and __STDC_VERSION__ even when used with options
that break C conformance, such as -fexcess-precision=fast (which is the
default).

Since these options are known to break C conformance on purpose, __STDC__ and
__STDC_VERSION__ should not be defined in such cases.