[Bug preprocessor/87299] New: use of -save-temps causes undue macro re-definition warning

[jbeulich at novell dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87299

            Bug ID: 87299
           Summary: use of -save-temps causes undue macro re-definition
                    warning
           Product: gcc
           Version: 8.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: preprocessor
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jbeulich at novell dot com
  Target Milestone: ---

This piece of code

#define x y
#pragma GCC target("avx512f")
#ifndef __AVX512F__
# define x z
#endif

wrongly triggers 'warning: "x" redefine' with -save-temps, but compiles
silently without.

Note that this is different from e.g. 57201 or 78497, albeit the underlying
theme looks to be the same.