[PATCH] ltmain.sh: allow more flags at link-time

[Eric Gallager]

On Wed, Aug 14, 2024 at 8:50 AM Sam James <sam@gentoo.org> wrote:
>
> libtool defaults to filtering flags passed at link-time.
>
> This brings the filtering in GCC's 'fork' of libtool into sync with
> upstream libtool commit 22a7e547e9857fc94fe5bc7c921d9a4b49c09f8e.

I think it'd be worthwhile to link to the upstream commit in the
ChangeLog / commit message, too. Also, are you sure that's the right
one? It looks just like a version revbump commit to me:
https://git.savannah.gnu.org/cgit/libtool.git/commit/?id=22a7e547e9857fc94fe5bc7c921d9a4b49c09f8e

>
> In particular, this now allows some harmless diagnostic flags (especially
> useful for things like -Werror=odr), more optimization flags, and some
> Clang-specific options.
>
> GCC's -flto documentation mentions:
> > To use the link-time optimizer, -flto and optimization options should be
> > specified at compile time and during the final link. It is recommended
> > that you compile all the files participating in the same link with the
> > same options and also specify those options at link time.
>
> This allows compliance with that.
>
>         * ltmain.sh (func_mode_link): Allow various flags through filter.
> ---
> We have been using this for a while now downstream.
>
> H.J., please take a look.
>
> I think this also explains https://src.fedoraproject.org/rpms/binutils/blob/rawhide/f/binutils.spec#_947.
>
>  ltmain.sh | 46 ++++++++++++++++++++++++++++++++++------------
>  1 file changed, 34 insertions(+), 12 deletions(-)
>
> diff --git a/ltmain.sh b/ltmain.sh
> index 493e83c36f14..79cd7c57f42e 100644
> --- a/ltmain.sh
> +++ b/ltmain.sh
> @@ -4966,19 +4966,41 @@ func_mode_link ()
>         arg="$func_quote_for_eval_result"
>         ;;
>
> -      # -64, -mips[0-9] enable 64-bit mode on the SGI compiler
> -      # -r[0-9][0-9]* specifies the processor on the SGI compiler
> -      # -xarch=*, -xtarget=* enable 64-bit mode on the Sun compiler
> -      # +DA*, +DD* enable 64-bit mode on the HP compiler
> -      # -q* pass through compiler args for the IBM compiler
> -      # -m*, -t[45]*, -txscale* pass through architecture-specific
> -      # compiler args for GCC
> -      # -F/path gives path to uninstalled frameworks, gcc on darwin
> -      # -p, -pg, --coverage, -fprofile-* pass through profiling flag for GCC
> -      # @file GCC response files
> -      # -tp=* Portland pgcc target processor selection
> +      # Flags to be passed through unchanged, with rationale:
> +      # -64, -mips[0-9]      enable 64-bit mode for the SGI compiler
> +      # -r[0-9][0-9]*        specify processor for the SGI compiler
> +      # -xarch=*, -xtarget=* enable 64-bit mode for the Sun compiler
> +      # +DA*, +DD*           enable 64-bit mode for the HP compiler
> +      # -q*                  compiler args for the IBM compiler
> +      # -m*, -t[45]*, -txscale* architecture-specific flags for GCC
> +      # -F/path              path to uninstalled frameworks, gcc on darwin
> +      # -p, -pg, --coverage, -fprofile-*  profiling flags for GCC
> +      # -fstack-protector*   stack protector flags for GCC
> +      # @file                GCC response files
> +      # -tp=*                Portland pgcc target processor selection
> +      # -O*, -g*, -flto*, -fwhopr*, -fuse-linker-plugin GCC link-time optimization
> +      # -specs=*             GCC specs files
> +      # -stdlib=*            select c++ std lib with clang
> +      # -fdiagnostics-color* simply affects output
> +      # -frecord-gcc-switches used to verify flags were respected
> +      # -fsanitize=*         Clang/GCC memory and address sanitizer
> +      # -fno-sanitize*       Clang/GCC memory and address sanitizer
> +      # -shared-libsan       Link with shared sanitizer runtimes (Clang)
> +      # -static-libsan       Link with static sanitizer runtimes (Clang)
> +      # -fuse-ld=*           Linker select flags for GCC
> +      # -rtlib=*             select c runtime lib with clang
> +      # --unwindlib=*        select unwinder library with clang
> +      # -f{file|debug|macro|profile}-prefix-map=* needed for lto linking
> +      # -Wa,*                Pass flags directly to the assembler
> +      # -Werror, -Werror=*   Report (specified) warnings as errors
>        -64|-mips[0-9]|-r[0-9][0-9]*|-xarch=*|-xtarget=*|+DA*|+DD*|-q*|-m*| \
> -      -t[45]*|-txscale*|-p|-pg|--coverage|-fprofile-*|-F*|@*|-tp=*)
> +      -t[45]*|-txscale*|-p|-pg|--coverage|-fprofile-*|-F*|@*|-tp=*| \
> +      -O*|-g*|-flto*|-fwhopr*|-fuse-linker-plugin|-fstack-protector*| \
> +      -stdlib=*|-rtlib=*|--unwindlib=*| \
> +      -specs=*|-fsanitize=*|-fno-sanitize*|-shared-libsan|-static-libsan| \
> +      -ffile-prefix-map=*|-fdebug-prefix-map=*|-fmacro-prefix-map=*|-fprofile-prefix-map=*| \
> +      -fdiagnostics-color*|-frecord-gcc-switches| \
> +      -fuse-ld=*|-Wa,*|-Werror|-Werror=*)
>          func_quote_for_eval "$arg"
>         arg="$func_quote_for_eval_result"
>          func_append compile_command " $arg"
> --
> 2.45.2
>