rust: avoid clobbering LIBS

  Save LIBS around calls to AC_SEARCH_LIBS to avoid clobbering $LIBS.

ChangeLog:

	* configure: Regenerate.
	* configure.ac: Save LIBS around calls to AC_SEARCH_LIBS.

Signed-off-by: Marc Poulhiès <dkm@kataplop.net>
Reviewed-by: Thomas Schwinge <tschwinge@baylibre.com>
Tested-by: Thomas Schwinge <tschwinge@baylibre.com>
---
Hello,

This has already been merged in our github repository: https://github.com/Rust-GCC/gccrs/pull/3121
When testing on Ubuntu 20.04, I (and Thomas, thanks for testing) get:
S["CRAB1_LIBS"]="-lpthread -ldl "
S["LIBS"]=""

So LIBS correctly stays unmodified by our calls to AC_SEARCH_LIBS.

Ok for master?

Marc

 configure    | 15 ++++++++-------
 configure.ac | 15 ++++++++-------
 2 files changed, 16 insertions(+), 14 deletions(-)
  

Hi Marc,

Patch looks good to me :) Thanks!

On 8/6/24 18:43, Marc Poulhiès wrote:
> Save LIBS around calls to AC_SEARCH_LIBS to avoid clobbering $LIBS.
> 
> ChangeLog:
> 
> 	* configure: Regenerate.
> 	* configure.ac: Save LIBS around calls to AC_SEARCH_LIBS.
> 
> Signed-off-by: Marc Poulhiès <dkm@kataplop.net>
> Reviewed-by: Thomas Schwinge <tschwinge@baylibre.com>
> Tested-by: Thomas Schwinge <tschwinge@baylibre.com>
> ---
> Hello,
> 
> This has already been merged in our github repository: https://github.com/Rust-GCC/gccrs/pull/3121
> When testing on Ubuntu 20.04, I (and Thomas, thanks for testing) get:
> S["CRAB1_LIBS"]="-lpthread -ldl "
> S["LIBS"]=""
> 
> So LIBS correctly stays unmodified by our calls to AC_SEARCH_LIBS.
> 
> Ok for master?
> 
> Marc
> 
>   configure    | 15 ++++++++-------
>   configure.ac | 15 ++++++++-------
>   2 files changed, 16 insertions(+), 14 deletions(-)
> 
> diff --git a/configure b/configure
> index 51bf1d1add1..e9583f2ba0c 100755
> --- a/configure
> +++ b/configure
> @@ -8878,9 +8878,12 @@ fi
>   
>   # Rust requires -ldl and -lpthread if you are using an old glibc that does not include them by
>   # default, so we check for them here
> -
> +# We are doing the test here and not in the gcc/configure to be able to nicely disable the
> +# build of the Rust frontend in case a dep is missing.
>   missing_rust_dynlibs=none
>   
> +save_LIBS="$LIBS"
> +LIBS=
>   { $as_echo "$as_me:${as_lineno-$LINENO}: checking for library containing dlopen" >&5
>   $as_echo_n "checking for library containing dlopen... " >&6; }
>   if ${ac_cv_search_dlopen+:} false; then :
> @@ -8993,16 +8996,14 @@ if test "$ac_res" != no; then :
>   
>   fi
>   
> +CRAB1_LIBS="$LIBS"
> +LIBS="$save_LIBS"
>   
> -if test "$ac_cv_search_dlopen" = -ldl; then
> -    CRAB1_LIBS="$CRAB1_LIBS -ldl"
> -elif test "$ac_cv_search_dlopen" = no; then
> +if test "$ac_cv_search_dlopen" = no; then
>       missing_rust_dynlibs="libdl"
>   fi
>   
> -if test "$ac_cv_search_pthread_create" = -lpthread; then
> -    CRAB1_LIBS="$CRAB1_LIBS -lpthread"
> -elif test "$ac_cv_search_pthread_create" = no; then
> +if test "$ac_cv_search_pthread_create" = no; then
>       missing_rust_dynlibs="$missing_rust_dynlibs, libpthread"
>   fi
>   
> diff --git a/configure.ac b/configure.ac
> index 20457005e29..f61dbe64a94 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -2039,21 +2039,22 @@ AC_SUBST(PICFLAG)
>   
>   # Rust requires -ldl and -lpthread if you are using an old glibc that does not include them by
>   # default, so we check for them here
> -
> +# We are doing the test here and not in the gcc/configure to be able to nicely disable the
> +# build of the Rust frontend in case a dep is missing.
>   missing_rust_dynlibs=none
>   
> +save_LIBS="$LIBS"
> +LIBS=
>   AC_SEARCH_LIBS([dlopen], [dl])
>   AC_SEARCH_LIBS([pthread_create], [pthread])
> +CRAB1_LIBS="$LIBS"
> +LIBS="$save_LIBS"
>   
> -if test "$ac_cv_search_dlopen" = -ldl; then
> -    CRAB1_LIBS="$CRAB1_LIBS -ldl"
> -elif test "$ac_cv_search_dlopen" = no; then
> +if test "$ac_cv_search_dlopen" = no; then
>       missing_rust_dynlibs="libdl"
>   fi
>   
> -if test "$ac_cv_search_pthread_create" = -lpthread; then
> -    CRAB1_LIBS="$CRAB1_LIBS -lpthread"
> -elif test "$ac_cv_search_pthread_create" = no; then
> +if test "$ac_cv_search_pthread_create" = no; then
>       missing_rust_dynlibs="$missing_rust_dynlibs, libpthread"
>   fi
>
  

August 12, 2024 at 4:09 PM, "Arthur Cohen" <arthur.cohen@embecosm.com> wrote:



> 
> Hi Marc,
> 
> Patch looks good to me :) Thanks!
> 

Hello,

thanks for the Ack :)

I'm still waiting for a maintainer review... I've been told this may qualify as "trivial", but again, I would prefer a formal Ack as I'm not really an expert in autotools...

Marc
  

Hello,

Gentle reminder for this simple autoconf patch :)

Thanks,
Marc
  

On Wed, Aug 28, 2024 at 11:10 AM Marc <dkm@kataplop.net> wrote:
>
> Hello,
>
> Gentle reminder for this simple autoconf patch :)

OK.

Note that completely wiping LIBS might remove requirements detected earlier,
like some systems require explicit -lc for example.  I would instead not clear
LIBS here and instead allow the possible duplicates through CRAB_LIBS.
YMMV of course.

Richard.

> Thanks,
> Marc
  

Richard Biener <richard.guenther@gmail.com> writes:

> On Wed, Aug 28, 2024 at 11:10 AM Marc <dkm@kataplop.net> wrote:
>>
>> Hello,
>>
>> Gentle reminder for this simple autoconf patch :)
>
> OK.
>
> Note that completely wiping LIBS might remove requirements detected earlier,
> like some systems require explicit -lc for example.  I would instead not clear
> LIBS here and instead allow the possible duplicates through CRAB_LIBS.
> YMMV of course.

Oh, that's a good remark. I've simply followed this suggestion that was
given on #gcc and also took inspiration from gcc/configure.ac that has
many instances of clearing LIBS like that. I think I'll merge it like
that, unless you see any reason this pattern would cause issue here (top
level) and not in gcc/configure.

Thank you,
Marc
  

On Tue, Sep 3, 2024 at 8:42 PM Marc <dkm@kataplop.net> wrote:
>
> Richard Biener <richard.guenther@gmail.com> writes:
>
> > On Wed, Aug 28, 2024 at 11:10 AM Marc <dkm@kataplop.net> wrote:
> >>
> >> Hello,
> >>
> >> Gentle reminder for this simple autoconf patch :)
> >
> > OK.
> >
> > Note that completely wiping LIBS might remove requirements detected earlier,
> > like some systems require explicit -lc for example.  I would instead not clear
> > LIBS here and instead allow the possible duplicates through CRAB_LIBS.
> > YMMV of course.
>
> Oh, that's a good remark. I've simply followed this suggestion that was
> given on #gcc and also took inspiration from gcc/configure.ac that has
> many instances of clearing LIBS like that. I think I'll merge it like
> that, unless you see any reason this pattern would cause issue here (top
> level) and not in gcc/configure.

If it's done like this elsewhere then it's good to follow existing
practice indeed.

Richard.

> Thank you,
> Marc
>
>