Re: [PATCH] configure: Replace -Wl,-r,-d with -Wl,-r

[Daniel Kiper]

On Tue, Feb 08, 2022 at 03:25:27PM -0800, Fangrui Song via Grub-devel wrote:
> In GNU ld and ld.lld, -d is used with -r to allocate space to COMMON symbols.
> This behavior is presumably to work around legacy projects which inspect
> relocatable output by themselves and do not handle COMMON symbols. grub does
> not do this.
>
> See https://github.com/llvm/llvm-project/issues/53660
> -d is quite useless and ld.lld may remove -d or make it a no-op for the
> 15.0.0 release.
> ---
>  acinclude.m4                |  2 +-
>  conf/Makefile.common        |  2 +-
>  grub-core/Makefile.core.def | 20 ++++++++++----------
>  grub-core/genmod.sh.in      |  4 ++--
>  4 files changed, 14 insertions(+), 14 deletions(-)
>
> diff --git a/acinclude.m4 b/acinclude.m4
> index 6e14bb553..fa7840f09 100644
> --- a/acinclude.m4
> +++ b/acinclude.m4
> @@ -430,7 +430,7 @@ link_nopie_needed=no]
>  AC_MSG_CHECKING([whether linker needs disabling of PIE to work])
>  AC_LANG_CONFTEST([AC_LANG_SOURCE([[]])])
>
> -[if eval "$ac_compile -Wl,-r,-d -nostdlib -Werror -o conftest.o" 2> 
> /dev/null; then]
> +[if eval "$ac_compile -Wl,-r -nostdlib -Werror -o conftest.o" 2> /dev/null; 
> then]

It looks that these changes do not break any builds. So, I am OK with
them. Though should not we add -fno-common to the CFLAGS too, e.g.:

diff --git a/configure.ac b/configure.ac
index 5c01af0fa..d1eaafee1 100644
--- a/configure.ac
+++ b/configure.ac
@@ -85,9 +85,9 @@ fi

 # Enable support for "restrict" keyword and other
 # features from gnu99 C language standard.
-BUILD_CFLAGS="-std=gnu99 $BUILD_CFLAGS"
-HOST_CFLAGS="-std=gnu99 $HOST_CFLAGS"
-TARGET_CFLAGS="-std=gnu99 $TARGET_CFLAGS"
+BUILD_CFLAGS="-std=gnu99 -fno-common $BUILD_CFLAGS"
+HOST_CFLAGS="-std=gnu99 -fno-common $HOST_CFLAGS"
+TARGET_CFLAGS="-std=gnu99 -fno-common $TARGET_CFLAGS"

 # Default HOST_CPPFLAGS
 HOST_CPPFLAGS="$HOST_CPPFLAGS -Wall -W"

Daniel