Sam James <[email protected]> writes:
> 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.
>
> 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(-)
Ping. The change should be harmless given the flags should be filtered
out earlier if anything is wrong, and we've been using it internally for
quite some time (i.e. it doesn't *add* the flags, just means that _if
they arrive_ at libtool, they're not dropped at link-time).
>
> 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"
