[PATCH] support: Link links-dso-program-c with libgcc_s only if available

[Sam James]

Florian Weimer <fweimer@redhat.com> writes:

> Add a configure check to detect bootstrapping builds that do not
> have libgcc_s.
>
> Fixes commit 3e2be87832781a29ed67f38f87c1ce3dd4c1b866 ("support: Link
> links-dso-program-c against libgcc_s").

Reviewed-by: Sam James <sam@gentoo.org>

>
> ---
>  configure        | 40 ++++++++++++++++++++++++++++++++++++++++
>  configure.ac     | 12 ++++++++++++
>  support/Makefile |  5 ++++-
>  3 files changed, 56 insertions(+), 1 deletion(-)
>
> diff --git a/configure b/configure
> index 674d1d7e4a..d11dcf97c5 100755
> --- a/configure
> +++ b/configure
> @@ -9135,6 +9135,46 @@ fi
>  config_vars="$config_vars
>  enable-static-pie = $libc_cv_static_pie"
>  
> +# Check if we can link support functionality against libgcc_s.
> +# Must not be used for linking installed binaries, to produce the
> +# same binaries for bootstrapped and bootstrapping builds (the latter
> +# with a GCC that does not build libgcc_s).
> +{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking whether $CC can link against -lgcc_s" >&5
> +printf %s "checking whether $CC can link against -lgcc_s... " >&6; }
> +if test ${libc_cv_have_libgcc_s+y}
> +then :
> +  printf %s "(cached) " >&6
> +else case e in #(
> +  e)   old_LIBS="$LIBS"
> +  LIBS="$LIBS -lgcc_s"
> +  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
> +/* end confdefs.h.  */
> +
> +int
> +main (void)
> +{
> +
> +  ;
> +  return 0;
> +}
> +_ACEOF
> +if ac_fn_c_try_link "$LINENO"
> +then :
> +  libc_cv_have_libgcc_s=yes
> +else case e in #(
> +  e) libc_cv_have_libgcc_s=no ;;
> +esac
> +fi
> +rm -f core conftest.err conftest.$ac_objext conftest.beam \
> +    conftest$ac_exeext conftest.$ac_ext
> +  LIBS="$old_LIBS" ;;
> +esac
> +fi
> +{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $libc_cv_have_libgcc_s" >&5
> +printf "%s\n" "$libc_cv_have_libgcc_s" >&6; }
> +config_vars="$config_vars
> +have-libgcc_s = $libc_cv_have_libgcc_s"
> +
>  # Support configure.ac under sysdeps.
>  
>  
> diff --git a/configure.ac b/configure.ac
> index 57cd24c87d..d068bb5082 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -2061,6 +2061,18 @@ if test "$libc_cv_static_pie" = "yes"; then
>  fi
>  LIBC_CONFIG_VAR([enable-static-pie], [$libc_cv_static_pie])
>  
> +# Check if we can link support functionality against libgcc_s.
> +# Must not be used for linking installed binaries, to produce the
> +# same binaries for bootstrapped and bootstrapping builds (the latter
> +# with a GCC that does not build libgcc_s).
> +AC_CACHE_CHECK([whether $CC can link against -lgcc_s], libc_cv_have_libgcc_s, [dnl
> +  old_LIBS="$LIBS"
> +  LIBS="$LIBS -lgcc_s"
> +  AC_LINK_IFELSE([AC_LANG_PROGRAM([[]], [[]])],
> +		 [libc_cv_have_libgcc_s=yes], [libc_cv_have_libgcc_s=no])
> +  LIBS="$old_LIBS"])
> +LIBC_CONFIG_VAR([have-libgcc_s], [$libc_cv_have_libgcc_s])
> +
>  # Support configure.ac under sysdeps.
>  AC_SUBST(libc_cv_test_cc_mprefer_vector_width)
>  AC_SUBST(test_enable_cet)
> diff --git a/support/Makefile b/support/Makefile
> index 0c670555ae..ea7b4cd4a0 100644
> --- a/support/Makefile
> +++ b/support/Makefile
> @@ -282,7 +282,10 @@ CFLAGS-temp_file.c += -D_FILE_OFFSET_BITS=64 -D_TIME_BITS=64
>  ifeq (,$(CXX))
>  LINKS_DSO_PROGRAM = links-dso-program-c
>  CFLAGS-links-dso-program-c.c += -fexceptions
> -LDLIBS-links-dso-program-c = -lgcc -lgcc_s $(libunwind)
> +LDLIBS-links-dso-program-c = -lgcc
> +ifeq ($(have-libgcc_s),yes)
> +LDLIBS-links-dso-program-c += -lgcc_s $(libunwind)
> +endif
>  else
>  LINKS_DSO_PROGRAM = links-dso-program
>  LDLIBS-links-dso-program = -lstdc++ -lgcc -lgcc_s $(libunwind)
>
> base-commit: 333b9ae8684d0d4c008e78d2820e3afc2e09f674