Hi Eric,
> I noticed the following, as part of investigating why autoconf on m4's tree
> was
> so slow on cygwin:
>
> $ cd m4
> $ autoconf --trace m4_syscmd --trace m4_esyscmd | wc
> 72 570 4742
>
> It turns out that my additions last September are the culprit [1, 2]. OK to
> apply this patch, which cuts down the number of syscmd forks from 72 to 2?
> Here's how the autoconf run looks when catching the error:
>
> $ mv lib/error.c{,.bak}
> $ autoconf -f
> missing lib/error.c
> configure.ac:68: error: problem checking LIBSOURCES
> m4/gnulib-comp.m4:42: M4_INIT is expanded from...
> configure.ac:68: the top level
> autom4te: /usr/local/bin/m4 failed with exit status: 1
Very good observation! When autoconf is slow, I usually blame 'm4', not
the number of forks :-)
I committed your patch with three small modifications:
- Add comments. It wasn't clear to me in the beginning why the two variables
were defined as m4 macros and not as shell variables (naive expectation).
- Change the error message to be a little more explicit:
$ autoconf -f
missing file gllib/error.c
configure.ac:114: error: expected source file, required through
AC_LIBSOURCES, not found
configure.ac:28: gl_INIT is expanded from...
configure.ac:114: the top level
autom4te: /packages/gnu/bin/m4 failed with exit status: 1
- Change the prefix of the two variables. The prefix "AC_" is not appropriate
since it's gnulib which defines them, not autoconf. Furthermore, when I see
how, in func_import, two blocks of
func_emit_initmacro_start/func_emit_initmacro_end are used to produce a
single gl_INIT macro, it is safer to prefix the variables with
"gl_" in one case and "gltests_" in the other case. Your version was not
wrong, since the variables are exploited in func_emit_initmacro_end,
not in func_emit_initmacro_done, but it's a walk on very thin ice.
Many thanks! It's tricky code.
Bruno
2008-05-13 Eric Blake <[EMAIL PROTECTED]>
Bruno Haible <[EMAIL PROTECTED]>
Reduce number of forks required during autoconf.
* gnulib-tool (func_emit_initmacro_start): Prepare gl_LIBSOURCES_LIST
and gl_LIBSOURCES_DIR.
(func_emit_initmacro_end): Use them here in a single m4_syscmd...
(func_emit_initmacro_done) <gl_LIBSOURCES>: ...rather than in one
m4_syscmd per file.
<m4_foreach_w>: Move...
* m4/gnulib-common.m4 (m4_foreach_w): ...here.
*** gnulib-tool.orig 2008-05-14 02:04:47.000000000 +0200
--- gnulib-tool 2008-05-14 01:59:13.000000000 +0200
***************
*** 2046,2051 ****
--- 2046,2059 ----
# We let automake know about the files to be distributed through the
# EXTRA_lib_SOURCES variable.
echo " m4_pushdef([AC_LIBSOURCES],
m4_defn([${macro_prefix_arg}_LIBSOURCES]))"
+ # Create data variables for checking the presence of files that are
mentioned
+ # as AC_LIBSOURCES arguments. These are m4 variables, not shell variables,
+ # because we want the check to happen when the configure file is created,
+ # not when it is run. ${macro_prefix_arg}_LIBSOURCES_LIST is the list of
+ # files to check for. ${macro_prefix_arg}_LIBSOURCES_DIR is the subdirectory
+ # in which to expect them.
+ echo " m4_pushdef([${macro_prefix_arg}_LIBSOURCES_LIST], [])"
+ echo " m4_pushdef([${macro_prefix_arg}_LIBSOURCES_DIR], [])"
echo " gl_COMMON"
}
***************
*** 2055,2060 ****
--- 2063,2085 ----
func_emit_initmacro_end ()
{
macro_prefix_arg="$1"
+ # Check the presence of files that are mentioned as AC_LIBSOURCES arguments.
+ # The check is performed only when autoconf is run from the directory where
+ # the configure.ac resides; if it is run from a different directory, the
+ # check is skipped.
+ echo " m4_ifval([${macro_prefix_arg}_LIBSOURCES_LIST], ["
+ echo " m4_syscmd([test ! -d ]${macro_prefix_arg}_LIBSOURCES_DIR[ ||"
+ echo " for gl_file in ]${macro_prefix_arg}_LIBSOURCES_LIST[ ; do"
+ echo " if test ! -r ]${macro_prefix_arg}_LIBSOURCES_DIR[/\$gl_file ;
then"
+ echo " echo \"missing file
]${macro_prefix_arg}_LIBSOURCES_DIR[/\$gl_file\" >&2"
+ echo " exit 1"
+ echo " fi"
+ echo " done])dnl"
+ echo " m4_if(m4_sysval, [0], [],"
+ echo " [AC_FATAL([expected source file, required through
AC_LIBSOURCES, not found])])"
+ echo " ])"
+ echo " m4_popdef([${macro_prefix_arg}_LIBSOURCES_DIR])"
+ echo " m4_popdef([${macro_prefix_arg}_LIBSOURCES_LIST])"
echo " m4_popdef([AC_LIBSOURCES])"
echo " m4_popdef([AC_REPLACE_FUNCS])"
echo " m4_popdef([AC_LIBOBJ])"
***************
*** 2090,2102 ****
echo " ${macro_prefix_arg}_LIBOBJS=\"\$${macro_prefix_arg}_LIBOBJS
\$1.\$ac_objext\""
echo "])"
echo
- echo "# m4_foreach_w is provided by autoconf-2.59c and later."
- echo "# This definition is to accommodate developers using versions"
- echo "# of autoconf older than that."
- echo "m4_ifndef([m4_foreach_w],"
- echo " [m4_define([m4_foreach_w],"
- echo " [m4_foreach([\$1], m4_split(m4_normalize([\$2]), [ ]), [\$3])])])"
- echo
echo "# Like AC_REPLACE_FUNCS, except that the module name goes"
echo "# into ${macro_prefix_arg}_LIBOBJS instead of into LIBOBJS."
echo "AC_DEFUN([${macro_prefix_arg}_REPLACE_FUNCS], ["
--- 2115,2120 ----
***************
*** 2111,2119 ****
echo "AC_DEFUN([${macro_prefix_arg}_LIBSOURCES], ["
echo " m4_foreach([_gl_NAME], [\$1], ["
echo " m4_if(_gl_NAME, [alloca.c], [], ["
! echo " m4_syscmd([test -r $sourcebase_arg/]_gl_NAME[ || test ! -d
$sourcebase_arg])dnl"
! echo " m4_if(m4_sysval, [0], [],"
! echo " [AC_FATAL([missing $sourcebase_arg/]_gl_NAME)])"
echo " ])"
echo " ])"
echo "])"
--- 2129,2136 ----
echo "AC_DEFUN([${macro_prefix_arg}_LIBSOURCES], ["
echo " m4_foreach([_gl_NAME], [\$1], ["
echo " m4_if(_gl_NAME, [alloca.c], [], ["
! echo " m4_define([${macro_prefix_arg}_LIBSOURCES_DIR],
[$sourcebase_arg])"
! echo " m4_append_uniq([${macro_prefix_arg}_LIBSOURCES_LIST], _gl_NAME,
[ ])"
echo " ])"
echo " ])"
echo "])"
*** m4/gnulib-common.m4.orig 2008-05-14 02:04:47.000000000 +0200
--- m4/gnulib-common.m4 2008-05-14 01:32:09.000000000 +0200
***************
*** 1,4 ****
! # gnulib-common.m4 serial 4
dnl Copyright (C) 2007-2008 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
--- 1,4 ----
! # gnulib-common.m4 serial 5
dnl Copyright (C) 2007-2008 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
***************
*** 31,36 ****
--- 31,43 ----
[Define to 1 when using the gnulib module ]$1[.])
])
+ # m4_foreach_w
+ # is a backport of autoconf-2.59c's m4_foreach_w.
+ # Remove this macro when we can assume autoconf >= 2.60.
+ m4_ifndef([m4_foreach_w],
+ [m4_define([m4_foreach_w],
+ [m4_foreach([$1], m4_split(m4_normalize([$2]), [ ]), [$3])])])
+
# AC_PROG_MKDIR_P
# is a backport of autoconf-2.60's AC_PROG_MKDIR_P.
# Remove this macro when we can assume autoconf >= 2.60.
