Eric Blake <ebb9 <at> byu.net> writes:
>
> As of this morning, autoconf.git now warns you on instances of expand-before-
> require (aka ordering bugs in older autoconf, and redundant output when using
> bleeding edge autoconf). I'm working on a series of patches to reduce the
> number of warnings we trigger, starting with this one:
Next:
configure.ac:44: warning: AC_REQUIRE: `gl_HEADER_ERRNO_H' was expanded before
it was required
m4/strerror.m4:18: gl_FUNC_STRERROR_SEPARATE is expanded from...
m4/strerror.m4:7: gl_FUNC_STRERROR is expanded from...
m4/gnulib-comp.m4:47: gl_INIT is expanded from...
configure.ac:44: the top level
Here, gnulib-tool was constructing gl_INIT to expand, rather than require
gl_HEADER_ERRNO_H; but since that macro in turn merely required
gl_HEADER_ERRNO_H_BODY, there was no actual out-of-order output (I don't know
any way to easily teach autoconf to avoid a false positive warning on a macro
that merely requires another macro as its sole content). But it is a lot
cleaner to fix it like this, by making the errno_h module require rather than
expand gl_HEADER_ERRNO_H in the first place, at which point, we no longer need
the indirection.
I'm pushing this:
From: Eric Blake <e...@byu.net>
Date: Wed, 21 Jan 2009 10:33:24 -0700
Subject: [PATCH] error: avoid expand-before-require warning
* modules/errno (configure.ac): Require, rather than expand,
gl_HEADER_ERRNO_H.
* m4/errno_h.m4 (gl_HEADER_ERRNO_H_BODY): Merge...
(gl_HEADER_ERRNO_H): ...into this macro, and use AC_DEFUN_ONCE to
enforce that all clients require it.
Signed-off-by: Eric Blake <e...@byu.net>
---
ChangeLog | 7 +++++++
m4/errno_h.m4 | 12 +++---------
modules/errno | 2 +-
3 files changed, 11 insertions(+), 10 deletions(-)
diff --git a/ChangeLog b/ChangeLog
index 7b7c8bd..bc8fc9f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,12 @@
2009-01-21 Eric Blake <e...@byu.net>
+ error: avoid expand-before-require warning
+ * modules/errno (configure.ac): Require, rather than expand,
+ gl_HEADER_ERRNO_H.
+ * m4/errno_h.m4 (gl_HEADER_ERRNO_H_BODY): Merge...
+ (gl_HEADER_ERRNO_H): ...into this macro, and use AC_DEFUN_ONCE to
+ enforce that all clients require it.
+
gnulib-tool: avoid warnings from using obsolete AC_GNU_SOURCE
* gnulib-tool (func_dest_tmpfilename, func_create_testdir): Using
obsolete AC_GNU_SOURCE causes out-of-order expansion; avoid it,
diff --git a/m4/errno_h.m4 b/m4/errno_h.m4
index 0682d1a..4d77672 100644
--- a/m4/errno_h.m4
+++ b/m4/errno_h.m4
@@ -1,17 +1,11 @@
-# errno_h.m4 serial 3
+# errno_h.m4 serial 4
dnl Copyright (C) 2004, 2006, 2008, 2009 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
dnl with or without modifications, as long as this notice is preserved.
-AC_DEFUN([gl_HEADER_ERRNO_H],
-[
- dnl Use AC_REQUIRE here, so that the default behavior below is expanded
- dnl once only, before all statements that occur in other macros.
- AC_REQUIRE([gl_HEADER_ERRNO_H_BODY])
-])
-
-AC_DEFUN([gl_HEADER_ERRNO_H_BODY],
+dnl This macro must pass through AC_REQUIRE (never directly invoke it).
+AC_DEFUN_ONCE([gl_HEADER_ERRNO_H],
[
AC_REQUIRE([AC_PROG_CC])
AC_CACHE_CHECK([for complete errno.h], [gl_cv_header_errno_h_complete], [
diff --git a/modules/errno b/modules/errno
index 8806621..208636d 100644
--- a/modules/errno
+++ b/modules/errno
@@ -9,7 +9,7 @@ Depends-on:
include_next
configure.ac:
-gl_HEADER_ERRNO_H
+AC_REQUIRE([gl_HEADER_ERRNO_H])
Makefile.am:
BUILT_SOURCES += $(ERRNO_H)
--
1.6.0.4
