Re: [PATCH] Allow the use of a listing file if the archiver supports it.

[Ralf Wildenhues]

Hi Peter,

* Peter Rosin wrote on Thu, Aug 12, 2010 at 03:28:57PM CEST:
> This is a patch that makes use of @FILE support in the
> archiver, if the archiver supports it. That makes linking
> succeed for long command lines when using MSVC, as MSVC
> can't do piecewise linking (-r -o) which is the current
> fallback. Absolute paths still needs work, but that will
> have to wait for Chucks work in that area.

Absolute paths are not a show stopper, for practical purposes.

This is ok for master with nits below addressed.

Thanks!
Ralf

> Subject: [PATCH] Allow the use of a listing file if the archiver supports it.
> 
> * libltdl/m4/libtool.m4 (_LT_CMD_OLD_ARCHIVE): Move detection
> of a suitable archiver...
> (_LT_PROG_AR): ...to here. New macro, also detect if the
> archiver supports a listing file with the new variable
> archiver_list_spec.
> * libltdl/config/ltmain.m4sh: If the archiver supports a listing
> file, use it when max_cmd_len is exceeded.  This is needed for
> tool chains such as MSVC which do not support piece by piece
> linking (-r -o).
> * doc/libtool.texi (libtool script contents): Update with
> archiver_list_spec description.

> --- a/doc/libtool.texi
> +++ b/doc/libtool.texi
> @@ -5875,6 +5875,10 @@ Commands used to create shared libraries, shared 
> libraries with
>  @option{-export-symbols} and static libraries, respectively.
>  @end defvar
>  
> address@hidden archiver_list_spec
> +How to feed a file listing to the archiver.
> address@hidden defvar

We already have

@defvar nm_file_list_spec
Specify filename containing input files for @code{NM}.
@end defvar

and I like that description a wee bit better, with s/NM/AR/.  WDYT?

> --- a/libltdl/config/ltmain.m4sh
> +++ b/libltdl/config/ltmain.m4sh
> @@ -7900,6 +7900,16 @@ EOF
>       len=$func_len_result
>       if test "$len" -lt "$max_cmd_len" || test "$max_cmd_len" -le -1; then
>         cmds=$old_archive_cmds
> +     elif test -n "$archiver_list_spec"; then
> +       func_verbose "using command file archive linking..."
> +       for obj in $oldobjs
> +       do
> +         $ECHO \""$obj"\"

Have you tried and ensured that those \"extra\" quotes are necessary
and no problem?  I'd leave them out otherwise.

> +       done > $output_objdir/$libname.libcmd
> +       save_oldobjs="$oldobjs"
> +       oldobjs=" $archiver_list_spec$output_objdir/$libname.libcmd"
> +       eval cmds=\"\$old_archive_cmds\"

This eval looks spurious, it should be sufficient to just say
          cmds=$old_archive_cmds

here.  You do need to remove or move down the following line then,
however:

> +       oldobjs="$save_oldobjs"

Rationale I'm being picky here: the extra eval expands '~' in file
names listed in $old_archive_cmds which then causes failures such as
<https://buildd.debian.org/fetch.cgi?pkg=libtool&arch=s390&ver=2.2.6b-2~bpo50%2B1&stamp=1266125841&file=log>
(Yes, I'm still not done with a general fix, but I'd like to avoid
proliferating the problem where possible.)

If my suggestions don't work, then feel free to go ahead with your
version, I'll make a note to investigate then.

> --- a/libltdl/m4/libtool.m4
> +++ b/libltdl/m4/libtool.m4
> @@ -1312,14 +1312,42 @@ need_locks="$enable_libtool_lock"
>  ])# _LT_ENABLE_LOCK
>  
>  
> +# _LT_PROG_AR
> +# -----------
> +m4_defun([_LT_PROG_AR],
> +[AC_CHECK_TOOLS(AR, [ar], false)
> +: ${AR=ar}
> +: ${AR_FLAGS=cru}
> +_LT_DECL([], [AR], [1], [The archiver])
> +_LT_DECL([], [AR_FLAGS], [1], [Flags to create an archive])
> +
> +AC_CACHE_CHECK([for archiver @FILE support], [lt_cv_ar_at_file],
> +  [lt_cv_ar_at_file=no
> +   AC_COMPILE_IFELSE([[int some_variable = 0;]],
> +     [echo conftest.$ac_objext > conftest.lst
> +      am_ar_try='$AR $AR_FLAGS libconftest.a @conftest.lst'
> +      AC_TRY_EVAL([am_ar_try])
> +      if test "$ac_status" -eq 0; then
> +        lt_cv_ar_at_file=@
> +      fi
> +      rm -f conftest.* libconftest.a
> +     ])
> +  ])
> +
> +if test "x$lt_cv_ar_at_file" = xno; then
> +  archiver_list_spec=
> +else
> +  archiver_list_spec=lt_cv_ar_at_file

There is a $ missing here.  I think this should cause at least some of
our current tests to fail.

> +fi
> +_LT_DECL([], [archiver_list_spec], [1],
> +  [How to feed a file listing to the archiver])
> +])# _LT_PROG_AR