https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88535
--- Comment #5 from john henning <mailboxnotfound at yahoo dot com> --- Thank you for the response. I wonder if the configure or make process should defend against the possibility that the host compiler and the compiler that we are building today have differing defaults for -m32 vs -m64. Consider below, where the /usr/bin compiler is provided by the OS, and the 8.2 is from a build without bootstrap. $ echo "int main(){}" > tmp.c $ /usr/bin/gcc tmp.c $ file a.out a.out: ELF 64-bit MSB executable SPARCV9 Version 1, dynamically linked, not stripped, no debugging information available $ $ /export/GCC/gcc-8.2.0/bin/gcc tmp.c $ file a.out a.out: ELF 32-bit MSB executable SPARC32PLUS Version 1, V8+ Required, dynamically linked, not stripped, no debugging information available $ Notice the differing output when one is silent about -m32 / -m64. (Note: Although the defaults differ, both the above are perfectly happy to build the non-default version if you are explicit for -m32 or -m64). Details for the system compiler: $ /usr/bin/gcc -v Using built-in specs. COLLECT_GCC=/usr/bin/gcc COLLECT_LTO_WRAPPER=/usr/gcc/7/lib/gcc/sparcv9-solaris2.11/7.3.0/lto-wrapper Target: sparcv9-solaris2.11 Configured with: /builds/ulhg/workspace/Solaris_11u4/Userland/full-build/02b-build-sparc/components/gcc7/gcc-7.3.0/configure --prefix=/usr/gcc/7 --mandir=/usr/gcc/7/share/man --bindir=/usr/gcc/7/bin --sbindir=/usr/gcc/7/sbin --libdir=/usr/gcc/7/lib --infodir=/usr/gcc/7/share/info --libexecdir=/usr/gcc/7/lib --enable-languages=c,c++,fortran,objc --enable-shared --enable-initfini-array --disable-rpath --with-system-zlib --with-build-config=no --with-gmp-include=/usr/include --with-mpfr-include=/usr/include --without-gnu-ld --with-ld=/usr/bin/ld --with-gnu-as --with-as=/usr/gnu/bin/as --disable-bootstrap 'BOOT_CFLAGS=-g -O2' sparcv9-solaris2.11 Thread model: posix gcc version 7.3.0 (GCC) $ And for the 8.2 without bootstrap: $ /export/GCC/gcc-8.2.0/bin/gcc -v Using built-in specs. COLLECT_GCC=/export/GCC/gcc-8.2.0/bin/gcc COLLECT_LTO_WRAPPER=/export/GCC/gcc-8.2.0-try1/bin/../libexec/gcc/sparc-sun-solaris2.11/8.2.0/lto-wrapper Target: sparc-sun-solaris2.11 Configured with: /export/home/johnh/gcc/build/gcc-8.2.0/configure --enable-languages=c,c++,fortran --enable-lto --without-system-zlib --with-included-gettext --disable-libvtv --disable-bootstrap --with-gnu-as --with-as=/usr/gnu/bin/as --with-gnu-ld --with-ld=/usr/gnu/bin/ld --with-pkgversion=johnh-14-Dec-2018 --prefix=/export/GCC/gcc-8.2.0 --with-local-prefix=/export/GCC Thread model: posix gcc version 8.2.0 (johnh-14-Dec-2018) $