Re: Use newer m4_map_args_{w,sep}

[Eric Blake]

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According to Paolo Bonzini on 11/11/2008 2:55 AM:
>>             'autoconf -f'  './config.status --recheck'   size
>> Pre-patch:  9.984s         8m42.414s                     977990
>> Post-patch: 10.081s        8m3.106s                      973966
>>
>> In my mind, the small slowdown in autoconf is tolerable in comparison to the 
>> speedup in configure.
> 
> Yeah, we have accumulated enough Autoconf speedup that we can definitely
> trade it for faster and more readable configure.  BTW, if there is no \
> in the AC_DEFINE_UNQUOTED argument you could still use AS_ECHO with a
> different second argument, can't you?

Hmm, you have a point.  First, consider:

AC_DEFINE_UNQUOTED([var], ["${foo-"bar blah"}"])

To preserve semantics in the conversion from unquoted here-doc to an echo,
that would have to be written:

AS_ECHO(["\"${foo-"bar blah"}\""])

So a simple AS_ESCAPE won't do the trick, and my original patch stuck with
a here-doc merely based on ".  On the other hand, " can only have
non-AS_ESCAPE semantics if there is also '${', '$(', or '`' (not that '$('
will appear in any portable script), but there are also other problematic
sequences without " in those three cases:

AS_DEFINE_UNQUOTED([var], [${foo-`echo oops`}])

which AS_ESCAPE would render as:

AS_ECHO(["${foo-\`echo oops\`}"])

So I altered the filter to look for those three patterns rather than ",
with the nice side-effect that one case missed by my original patch:

cat >>confdefs.h <<_ACEOF
#define PACKAGE_NAME "$PACKAGE_NAME"
_ACEOF

is now converted to AS_ECHO.  And while reviewing, I noticed some other
simplifications (rather than choosing between m4_expand or m4_quote based
on $1 in the second macro, I blindly call m4_expand in the first macro),
so here's the updated patch I'm planning on installing, after I run the
full testsuite:

- --
Don't work too hard, make some time for fun as well!

Eric Blake             address@hidden
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>From 33071fb4a77d4d062845107fd35d39524deb0122 Mon Sep 17 00:00:00 2001
From: Eric Blake <address@hidden>
Date: Mon, 10 Nov 2008 17:14:37 -0700
Subject: [PATCH] Reduce forks in AC_DEFINE.

* lib/autoconf/general.m4 (_AC_DEFINE_Q_PRINT): New macro.
(_AC_DEFINE_Q): Use it to avoid forks for all AC_DEFINE and most
AC_DEFINE_UNQUOTED.
* tests/torture.at (Substitute and define special characters):
(Define to a 2000-byte string): Enhance tests to cover
AC_DEFINE_UNQUOTED.

Signed-off-by: Eric Blake <address@hidden>
---
 ChangeLog               |   10 ++++++++++
 lib/autoconf/general.m4 |   21 +++++++++++++++++----
 tests/torture.at        |   22 ++++++++++++++++------
 3 files changed, 43 insertions(+), 10 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index b28abcd..fc611ae 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,13 @@
+2008-11-11  Eric Blake  <address@hidden>
+
+       Reduce forks in AC_DEFINE.
+       * lib/autoconf/general.m4 (_AC_DEFINE_Q_PRINT): New macro.
+       (_AC_DEFINE_Q): Use it to avoid forks for all AC_DEFINE and most
+       AC_DEFINE_UNQUOTED.
+       * tests/torture.at (Substitute and define special characters):
+       (Define to a 2000-byte string): Enhance tests to cover
+       AC_DEFINE_UNQUOTED.
+
 2008-11-10  Eric Blake  <address@hidden>
 
        Work around <=m4-1.4.9 bug in m4_format.
diff --git a/lib/autoconf/general.m4 b/lib/autoconf/general.m4
index 15377cb..7c8fe6b 100644
--- a/lib/autoconf/general.m4
+++ b/lib/autoconf/general.m4
@@ -2090,13 +2090,26 @@ m4_define([_AC_DEFINE_Q],
 [: `$3' is not a valid preprocessor define value])])]dnl
 [m4_ifval([$4], [AH_TEMPLATE(AC_name, [$4])])]dnl
 [_m4_popdef([AC_name])]dnl
-[cat >>confdefs.h <<$1_ACEOF
address@hidden:@define] $2 m4_if([$#], 2, 1, [$3], [], [/**/], [$3])
-_ACEOF
+[$0_PRINT([$1], m4_expand(address@hidden:@define] $2 ]m4_if([$#], 2, 1,
+  [$3], [], [/**/], [[$3]])))])
+
+# _AC_DEFINE_Q_PRINT(QUOTE, STRING)
+# ---------------------------------
+# Append the pre-expanded STRING and a trailing newline to confdefs.h,
+# as if by a here-doc with QUOTE determining whether the here-doc is
+# quoted.  However, since using cat on a here-doc involves forking,
+# try to use AS_ECHO when possible.
+m4_define([_AC_DEFINE_Q_PRINT],
+[m4_cond([[$1]], [\],
+  [AS_ECHO(["AS_ESCAPE([[$2]])"]) >>confdefs.h],
+         [m4_bregexp([$2], [\$(\|\${\|`])], [-1],
+  [AS_ECHO(["AS_ESCAPE([$2], [""])"]) >>confdefs.h],
+  [cat >>confdefs.h <<_ACEOF
+[$2]
+_ACEOF])
 ])
 
 
-
 ## -------------------------- ##
 ## Setting output variables.  ##
 ## -------------------------- ##
diff --git a/tests/torture.at b/tests/torture.at
index 586d0f8..a68657f 100644
--- a/tests/torture.at
+++ b/tests/torture.at
@@ -756,16 +756,19 @@ AT_CLEANUP
 ## ------------------------------ ##
 
 AT_SETUP([Define to a 2000-byte string])
+AT_KEYWORDS([AC@&address@hidden AC@&address@hidden)
 
 AT_CONFIGURE_AC(
 [[
-AC_DEFINE([foo], ]m4_for([n], 1, 100,, ....................)[, [desc])
+AC_DEFINE_UNQUOTED([foo], ]m4_for([n], 1, 100,, ....................)[, [desc])
+AC_DEFINE([fooq], ]m4_for([n], 1, 100,, ....................)[, [desc])
 ]])
 
 AT_CHECK_AUTOCONF
 AT_CHECK_AUTOHEADER
 AT_CHECK_CONFIGURE
 AT_CHECK_DEFINES(address@hidden:@define foo m4_for([n], 1, 100,, 
....................)
address@hidden:@define fooq m4_for([n], 1, 100,, ....................)
 ])
 AT_CLEANUP
 
@@ -777,6 +780,7 @@ AT_CLEANUP
 # Use characters special to the shell, sed, awk, and M4.
 
 AT_SETUP([Substitute and define special characters])
+AT_KEYWORDS([AC@&address@hidden AC@&address@hidden)
 
 AT_DATA([Foo.in], address@hidden@
 @bar@@notsubsted@@baz@ stray @ and more@@@baz@
@@ -800,7 +804,8 @@ AT_DATA([Zardoz.in], address@hidden@
 ])
 
 AT_CONFIGURE_AC(
-[[foo="AS@&address@hidden([[X*'[]+ ",& &`\($foo \& \\& \\\& \\\\& \ \\ \\\ 
!]])"
+[[foo="AS@&address@hidden([[X*'[]+ ", & &`\($foo \& \\& \\\& \\\\& \ \\ \\\ 
!]])"
+#"
 bar="@foo@ @baz@"
 baz=bla
 ( for i in 0 1 2 3; do
@@ -824,8 +829,10 @@ AC_SUBST([baz])
 AC_SUBST([zardoz])
 file=File
 AC_SUBST_FILE([file])
-AC_DEFINE([foo], [[X*'[]+ ",& &`\($foo !]], [Awful value.])
-AC_DEFINE([bar], [[%!_!# X]], [Value that is used as special delimiter.])
+AC_DEFINE([fooq], [[X*'[]+ ", & &`\($foo !]], [Awful value.])
+AC_DEFINE([barq], [[%!_!# X]], [Value that is used as special delimiter.])
+AC_DEFINE_UNQUOTED([foo], [[X*'[]+ ", & &\`\\(\$foo !]], [Awful value.])
+AC_DEFINE_UNQUOTED([bar], [[%!_!# X]], [Value that is used as special 
delimiter.])
 AC_PROG_AWK
 AC_CONFIG_FILES([Foo Zardoz])]])
 
@@ -834,7 +841,7 @@ AT_CHECK_AUTOHEADER
 # Check both awk and the result of AC_PROG_AWK
 for awk_arg in FOO= AWK=awk; do
   AT_CHECK_CONFIGURE([$awk_arg])
-  AT_CHECK([cat Foo], 0, [[X*'[]+ ",& &`\($foo \& \\& \\\& \\\\& \ \\ \\\ !
+  AT_CHECK([cat Foo], 0, [[X*'[]+ ", & &`\($foo \& \\& \\\& \\\\& \ \\ \\\ !
 @foo@ @baz@@address@hidden stray @ and more@@bla
 address@hidden@ @address@hidden@baz
 address@hidden@ @address@hidden
@@ -849,7 +856,9 @@ address@hidden@
 ]])
   AT_CHECK([cmp allowed-chars Zardoz])
   AT_CHECK_DEFINES([[#define bar %!_!# X
-#define foo X*'[]+ ",& &`\($foo !
+#define barq %!_!# X
+#define foo X*'[]+ ", & &`\($foo !
+#define fooq X*'[]+ ", & &`\($foo !
 ]])
 done
 AT_CLEANUP
@@ -900,6 +909,7 @@ AT_CLEANUP
 ## ------------------ ##
 
 AT_SETUP([Define a newline])
+AT_KEYWORDS([AC@&address@hidden AC@&address@hidden)
 AT_CONFIGURE_AC([[AC_DEFINE([foo], [one
 two], [This spans two lines.])
 ]])
-- 
1.6.0.2