Had a similar problem with gcc-15
i installed a fresh msys Environment and downloaded below packages from https://repo.msys2.org/mingw/
pacman -U mingw-w64-i686-gcc-libs-14.2.0-3-any.pkg.tar.zst
pacman -U mingw-w64-i686-gcc-14.2.0-3-any.pkg.tar.zst
pacman -Ss base-devel