[Bug libstdc++/84654] New: libstdc++ tries to use __float128 when compiling with -mno-float128

[tuliom at linux dot vnet.ibm.com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84654

            Bug ID: 84654
           Summary: libstdc++ tries to use __float128 when compiling with
                    -mno-float128
           Product: gcc
           Version: 8.0.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: tuliom at linux dot vnet.ibm.com
  Target Milestone: ---

Using the following test program:

$ cat test1.cpp 
#include <math.h>
int main() {
    return 0;
}

$ g++-8 -mno-float128 test.cpp 
In file included from /usr/include/c++/8/cmath:47,
                 from /usr/include/c++/8/math.h:36,
                 from test.cpp:1:
/usr/include/c++/8/bits/std_abs.h:101:3: error: ‘__float128’ does not name a
type; did you mean ‘__floorl’?
   __float128
   ^~~~~~~~~~
   __floorl

I reproduced this problem on powerpc64le.

I have a patch to fix this.