https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103980
--- Comment #7 from Andrew Pinski <pinskia at gcc dot gnu.org> --- It might be the case Wdouble-promotion is just useless on s390 if you configure your compiler with --enable-s390-excess-float-precision which was only added for GCC11, so basically between GCC 7 and GCC 10.x, the default was to promote all float to double for s390.
