From: Eric Blake <ebb9@byu.net>
Date: Sat, 18 Oct 2008 13:27:45 +0000 (-0600)
Subject: Document bugs in { } handling.
X-Git-Tag: v2.63b~231
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=af61badc821bcef780650da9032adbc4d86d1db5;p=thirdparty%2Fautoconf.git

Document bugs in { } handling.

* doc/autoconf.texi (Limitations of Builtins): Mention bug on
empty list.

Signed-off-by: Eric Blake <ebb9@byu.net>
---

diff --git a/ChangeLog b/ChangeLog
index d971b188..25c8826a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,9 @@
 2008-10-18  Eric Blake  <ebb9@byu.net>
 
+	Document bugs in { } handling.
+	* doc/autoconf.texi (Limitations of Builtins): Mention bug on
+	empty list.
+
 	Fix some testsuite failures introduced two days ago.
 	* tests/m4sh.at (Nested AS@&t@_REQUIRE_SHELL_FN)
 	(AS@&t@_REQUIRE_SHELL_FN and m4@&t@_require): Adjust to changed
diff --git a/doc/autoconf.texi b/doc/autoconf.texi
index a6bcb341..eed40c56 100644
--- a/doc/autoconf.texi
+++ b/doc/autoconf.texi
@@ -14624,6 +14624,22 @@ bash: line 1: /bad: Permission denied
 1
 @end example
 
+Posix requires a syntax error if a brace list has no contents.  However,
+not all shells obey this rule; and on shells where empty lists are
+permitted, the effect on @samp{$?} is inconsistent.  To avoid problems,
+ensure that a brace list is never empty.
+
+@example
+$ @kbd{bash -c 'false; @{ @}; echo $?' || echo $?}
+bash: line 1: syntax error near unexpected token `@}'
+bash: line 1: `false; @{ @}; echo $?'
+2
+$ @kbd{zsh -c 'false; @{ @}; echo $?' || echo $?}
+1
+$ @kbd{pdksh -c 'false; @{ @}; echo $?' || echo $?}
+0
+@end example
+
 
 @item @command{break}
 @c ------------------