https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103866
--- Comment #12 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Jonathan Wakely <r...@gcc.gnu.org>: https://gcc.gnu.org/g:68c2e9e9234cb301e9e81792cad233a41e797792 commit r12-6409-g68c2e9e9234cb301e9e81792cad233a41e797792 Author: Jonathan Wakely <jwak...@redhat.com> Date: Thu Jan 6 13:54:53 2022 +0000 libstdc++: Fix and simplify freestanding configuration [PR103866] This fixes the --disable-hosted-libstdcxx build so that it works with --without-headers. Currently you need to also use --with-newlib, which is confusing for users who aren't actually using newlib. The AM_PROG_LIBTOOL checks are currently skipped for --with-newlib and --with-avrlibc builds, with this change they are also skipped when using --without-headers. It would be nice if using --disable-hosted-libstdcxx automatically skipped those checks, but GLIBCXX_ENABLE_HOSTED comes too late to make the AM_PROG_LIBTOOL checks depend on $is_hosted. The checks for EOF, SEEK_CUR etc. cause the build to fail if there is no <stdio.h> available. Unlike most headers, which get a HAVE_FOO_H macro, <stdio.h> is in autoconf's default includes, so every check tries to include it unconditionally. This change skips those checks for freestanding builds. Similarly, the checks for <stdint.h> types done by GCC_HEADER_STDINT try to include <stdio.h> and fail for --without-headers builds. This change skips the use of GCC_HEADER_STDINT for freestanding. We can probably stop using GCC_HEADER_STDINT entirely, since only one file uses the gstdint.h header that is generated, and that could easily be changed to use <stdint.h> instead. That can wait for stage 1. We also need to skip the GLIBCXX_CROSSCONFIG stage if --without-headers was used, since we don't have any of the functions it deals with. The end result of the changes above is that it should not be necessary for a --disable-hosted-libstdcxx --without-headers build to also use --with-newlib. Finally, compile libsupc++ with -ffreestanding when --without-headers is used, so that <stdint.h> will use <gcc-stdint.h> instead of expecting it to come from libc. libstdc++-v3/ChangeLog: PR libstdc++/103866 * acinclude.m4 (GLIBCXX_COMPUTE_STDIO_INTEGER_CONSTANTS): Do nothing for freestanding builds. (GLIBCXX_ENABLE_HOSTED): Define FREESTANDING_FLAGS. * configure.ac: Do not use AC_LIBTOOL_DLOPEN when configured with --without-headers. Do not use GCC_HEADER_STDINT for freestanding builds. * libsupc++/Makefile.am (HOSTED_CXXFLAGS): Use -ffreestanding for freestanding builds. * configure: Regenerate. * Makefile.in: Regenerate. * doc/Makefile.in: Regenerate. * include/Makefile.in: Regenerate. * libsupc++/Makefile.in: Regenerate. * po/Makefile.in: Regenerate. * python/Makefile.in: Regenerate. * src/Makefile.in: Regenerate. * src/c++11/Makefile.in: Regenerate. * src/c++17/Makefile.in: Regenerate. * src/c++20/Makefile.in: Regenerate. * src/c++98/Makefile.in: Regenerate. * src/filesystem/Makefile.in: Regenerate. * testsuite/Makefile.in: Regenerate.
