Re: autoconf doc fixes for `...` gotchas

[Ralf Wildenhues]

Hi Paul,

* Paul Eggert wrote on Fri, Jan 21, 2005 at 01:05:47AM CET:
>
> 2005-01-20  Paul Eggert  <address@hidden>
> 
>       * doc/autoconf.texi (Shell Substitutions): Fix typo in case statement.
>       Warn about newline stripping in `` and $().  Update Solaris
>       version to 9.
>       (Limitations of Builtins): Use expr "X...", not expr "x...", as
>       X insulates us from future changes to Posix.

Could you be bothered to elaborate what those changes are?

*snip*
> Index: autoconf.texi
> ===================================================================
> RCS file: /cvsroot/autoconf/autoconf/doc/autoconf.texi,v
> retrieving revision 1.864
> diff -u address@hidden -r1.864 autoconf.texi
> --- autoconf.texi     20 Jan 2005 10:59:57 -0000      1.864
> +++ autoconf.texi     21 Jan 2005 00:02:18 -0000
> @@ -11155,7 +11163,7 @@ @node Limitations of Builtins
>  or better yet
>  
>  @example
> -expr "x$ac_feature" : '.*[^-a-zA-Z0-9_]' >/dev/null &&
> +expr "X$ac_feature" : '.*[^-a-zA-Z0-9_]' >/dev/null &&
>    @var{action}
>  @end example
>  

If you do this, please also do this (and maybe note the significance of
X over x):

--- doc/autoconf.texi   24 Jan 2005 12:24:02 -0000      1.867
+++ doc/autoconf.texi   28 Jan 2005 09:35:08 -0000
@@ -11541,8 +11541,8 @@
 @item @command{expr}
 @c -----------------
 @prindex @command{expr}
-No @command{expr} keyword starts with @samp{x}, so use @samp{expr
-x"@var{word}" : 'address@hidden'} to keep @command{expr} from
+No @command{expr} keyword starts with @samp{X}, so use @samp{expr
+X"@var{word}" : 'address@hidden'} to keep @command{expr} from
 misinterpreting @var{word}.
 
 Don't use @code{length}, @code{substr}, @code{match} and @code{index}.


Regards,
Ralf