[Bug c/81841] New: i386: weird gcc -C error when including math.h

["bunk at stusta dot de" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81841

            Bug ID: 81841
           Summary: i386: weird gcc -C error when including math.h
           Product: gcc
           Version: 6.3.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: bunk at stusta dot de
  Target Milestone: ---

$ cat test.c
#include <math.h>
$ gcc -m64 -c -C test.c -O0
$ gcc -m64 -c -C test.c -O1
$ gcc -m32 -c -C test.c -O0
$ gcc -m32 -c -C test.c -O1
In file included from /usr/include/math.h:472:0,
                 from test.c:1:
/usr/include/bits/mathinline.h: In function ‘floor’:
/usr/include/bits/mathinline.h:746:1: error: expected ‘:’ or ‘)’ before string
constant
 __inline_mathcodeNP (floor, __x, \
 ^
/usr/include/bits/mathinline.h: In function ‘floorf’:
/usr/include/bits/mathinline.h:746:1: error: expected ‘:’ or ‘)’ before string
constant
 __inline_mathcodeNP (floor, __x, \
 ^
/usr/include/bits/mathinline.h: In function ‘floorl’:
/usr/include/bits/mathinline.h:746:1: error: expected ‘:’ or ‘)’ before string
constant
 __inline_mathcodeNP (floor, __x, \
 ^
/usr/include/bits/mathinline.h: In function ‘ceil’:
/usr/include/bits/mathinline.h:764:1: error: expected ‘:’ or ‘)’ before string
constant
 __inline_mathcodeNP (ceil, __x, \
 ^
/usr/include/bits/mathinline.h: In function ‘ceilf’:
/usr/include/bits/mathinline.h:764:1: error: expected ‘:’ or ‘)’ before string
constant
 __inline_mathcodeNP (ceil, __x, \
 ^
/usr/include/bits/mathinline.h: In function ‘ceill’:
/usr/include/bits/mathinline.h:764:1: error: expected ‘:’ or ‘)’ before string
constant
 __inline_mathcodeNP (ceil, __x, \
 ^
$ gcc -m32 -c test.c -O1
$ gcc -m32 -c -C test.c -O1 -save-temps 
$ gcc -m32 -c -C test.i -O1
$

Reproduced with both the Debian package of 6.3.0 in Debian stable and the
Debian package of 7.1.0 in Debian unstable, in both cases glibc 2.24 is used.