Re: AS_IF breakage

[Eric Blake]

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According to Ralf Wildenhues on 4/14/2009 11:49 AM:
> Hi Eric,

Hi Ralf,

>> $ zsh -c 'emulate sh; false; $empty; echo $?'
>> 1
> 
> Present in zsh 4.3.6, not present in zsh 4.3.4, BTW.

I'm still trying to figure out where best to document this in the manual.

> Here's an idea: let's not be smarter than we can be.
> 
>> So, would we rather write:
> [...]
>> or revert today's patch to the simpler
>>
>> m4_define([_AS_IF_ELSE],
>> [m4_ifnblank([$1],
>> [else
>>   $1
>> ])])
> 
> That is my favorite; along with not promising that we avoid shell syntax
> errors at all costs.

That was my conclusion as well.  I'm pushing this, once a full testsuite
run finishes:

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

Eric Blake             address@hidden
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>From f5a63e04f39bdd9ec452dd5332e24c4aad0b45bb Mon Sep 17 00:00:00 2001
From: Eric Blake <address@hidden>
Date: Tue, 14 Apr 2009 19:06:27 -0600
Subject: [PATCH] Fix yesterday's regression in AS_IF.

* lib/m4sugar/m4sh.m4 (_AS_IF_ELSE): Don't corrupt $? in else
branch; the user has to avoid syntax errors.
* tests/m4sh.at (AS@&address@hidden and AS@&address@hidden): Adjust test.

Signed-off-by: Eric Blake <address@hidden>
---
 ChangeLog           |    7 +++++++
 lib/m4sugar/m4sh.m4 |    2 +-
 tests/m4sh.at       |    5 ++++-
 3 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 68cd416..b6af52a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2009-04-14  Eric Blake  <address@hidden>
+
+       Fix yesterday's regression in AS_IF.
+       * lib/m4sugar/m4sh.m4 (_AS_IF_ELSE): Don't corrupt $? in else
+       branch; the user has to avoid syntax errors.
+       * tests/m4sh.at (AS@&address@hidden and AS@&address@hidden): Adjust 
test.
+
 2009-04-14  Ralf Wildenhues  <address@hidden>

        Add traces for AM_SILENT_RULES.
diff --git a/lib/m4sugar/m4sh.m4 b/lib/m4sugar/m4sh.m4
index 052c7eb..3c05201 100644
--- a/lib/m4sugar/m4sh.m4
+++ b/lib/m4sugar/m4sh.m4
@@ -609,7 +609,7 @@ m4_define([_AS_IF],
 ])
 m4_define([_AS_IF_ELSE],
 [m4_ifnblank([$1],
-[else :
+[else
   $1
 ])])

diff --git a/tests/m4sh.at b/tests/m4sh.at
index 5f7dc84..065a9dd 100644
--- a/tests/m4sh.at
+++ b/tests/m4sh.at
@@ -862,8 +862,11 @@ AS_CASE([foo], [foo], m4_do(AS_CASE([bar], [bar], [echo 
sixteen])))
 dnl Handle blank arguments.
 AS_IF([false], [:], [ ]) && AS_CASE([foo], [foo], []
 ) && echo seventeen
-m4_define([empty])AS_IF([false], [:], [empty]
+m4_define([empty])AS_IF([:], [empty]
 ) && AS_CASE([foo], [foo], [empty]) && echo eighteen
+dnl We can't handle AS_IF([false], [:], [empty]) unless m4_expand is
+dnl taught how to handle m4_require.  The user is responsible for
+dnl avoiding the syntax error in that case.

 # check that require works correctly
 m4_for([n], 1, 9, [],
-- 
1.6.1.2