Re: m4sugar and m4 1.6, bison

[Eric Blake]

Eric Blake <ebb9 <at> byu.net> writes:

> 
> The second patch is for something I discovered when trying to fix bison's 
usage 
> of m4sugar [1].  Bison forked m4sugar somewhere in between autoconf 2.59 and 
> 2.59c, then added m4_prepend, and skips the m4_PACKAGE_* macros defined in 
> autoconf's version.m4.

I have completed patching the argv_ref branch of m4.git to perform m4_append in 
linear rather than quadratic time; more details in a later email:
http://git.savannah.gnu.org/gitweb/?p=m4.git;a=shortlog;h=refs/heads/argv_ref

It turns out that 'git grep m4_prepend' turns up nothing of interest in 
bison.git, so apparantly, bison is not using it anymore (as of 2006-01-03, 
http://git.savannah.gnu.org/gitweb/?p=bison.git;a=commitdiff;h=8f7e3cf).  
Should I go ahead and revert my addition of m4_prepend altogether, seeing as 
how it is an inferior interface to m4_append (now that I have a concrete O(n) 
rather than O(n^2) m4 implementation, at least on the argv_ref branch)?

Also, I needed this followup commit, so that bison doesn't try dereferencing 
m4_defn(m4_PACKAGE_VERSION) in creating the definition of m4_version_prereq 
(the m4_fatal alternate is so that it will be immediately apparent why 
m4_version_prereq does not work in bison, which lacks m4sugar/version.m4).

From: Eric Blake <address@hidden>
Date: Tue, 15 Jul 2008 14:53:21 -0600
Subject: [PATCH] Avoid failure if version.m4 is omitted but m4_PACKAGE_* unused.

* lib/m4sugar/m4sugar.m4 (m4_version_compare): Provide alternate
definition for non-Autoconf clients of m4sugar.

Signed-off-by: Eric Blake <address@hidden>
---
 ChangeLog              |    6 ++++++
 lib/m4sugar/m4sugar.m4 |   14 ++++++++------
 2 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 8ae2ef6..6491d76 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2008-07-15  Eric Blake  <address@hidden>
+
+       Avoid failure if version.m4 is omitted but m4_PACKAGE_* unused.
+       * lib/m4sugar/m4sugar.m4 (m4_version_compare): Provide alternate
+       definition for non-Autoconf clients of m4sugar.
+
 2008-07-14  Eric Blake  <address@hidden>
 
        Tighten bound of potential speed of m4_append.
diff --git a/lib/m4sugar/m4sugar.m4 b/lib/m4sugar/m4sugar.m4
index a4d6f12..88eebf0 100644
--- a/lib/m4sugar/m4sugar.m4
+++ b/lib/m4sugar/m4sugar.m4
@@ -2243,12 +2243,14 @@ m4_sinclude([m4sugar/version.m4])
 # ----------------------------------------------------
 # Check this Autoconf version against VERSION.
 m4_define([m4_version_prereq],
-[m4_if(m4_version_compare(]m4_dquote(m4_defn([m4_PACKAGE_VERSION]))[, [$1]),
-       [-1],
-       [m4_default([$3],
-                  [m4_fatal([Autoconf version $1 or higher is required],
-                            [63])])],
-       [$2])])
+m4_ifdef([m4_PACKAGE_VERSION],
+[[m4_if(m4_version_compare(]m4_dquote(m4_defn([m4_PACKAGE_VERSION]))[, [$1]),
+       [-1],
+       [m4_default([$3],
+                   [m4_fatal([Autoconf version $1 or higher is required],
+                             [63])])],
+       [$2])]],
+[[m4_fatal([m4sugar/version.m4 not found])]]))
 
 
 
-- 
1.5.6