[Bug middle-end/122082] complex multiply: w * conj(w) should have zero imaginary part

[tydeman at tybor dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=122082

--- Comment #10 from Fred J. Tydeman <tydeman at tybor dot com> ---
You are correct in that there was a problem with that test.
Here is a corrected version:

#include <assert.h>
#include <limits.h>
#include <errno.h>
#include <stdio.h>
#include <float.h>
#include <fenv.h>
#include <complex.h>
#include <math.h>       /* glibc 2.41-11 */

#pragma STDC FENV_ACCESS ON
#pragma STDC FP_CONTRACT OFF
#pragma STDC FENV_ROUND FE_TONEAREST
#pragma STDC FENV_DEC_ROUND FE_DEC_TONEAREST
#pragma STDC CX_LIMITED_RANGE OFF

int main(void){
  if(1){
    float complex fc26;
    int flags;
    errno = 0;
    feclearexcept(FE_ALL_EXCEPT);
    fc26 = CMPLXF(FLT_MAX,1.1F) * CMPLXF(FLT_MAX,-1.1F); /* w * conj(w) */
    flags = fetestexcept(FE_ALL_EXCEPT);
    (void)printf("%Lg=cimagf(fc26)\n", (long double)cimagf(fc26) );
    (void)fflush(NULL);
    assert( 0 == errno );
    assert( FE_OVERFLOW & flags );
    assert( FE_INEXACT  & flags );
    assert( INFINITY == crealf(fc26) );
    assert( !isnan(cimagf(fc26)) || (0.f == cimagf(fc26)) || (!(FE_INVALID &
flags)) ); /* fails here */
  }
  return 0;
}