* doc/autoconf.texi (Here-Documents): We now know more about
	the variable expansion in here documents bug.
	Thanks to Tim Rice and Stepan Kasal.

Index: doc/autoconf.texi
===================================================================
RCS file: /cvsroot/autoconf/autoconf/doc/autoconf.texi,v
retrieving revision 1.1021
diff -u -r1.1021 autoconf.texi
--- doc/autoconf.texi	22 May 2006 17:27:50 -0000	1.1021
+++ doc/autoconf.texi	25 May 2006 05:58:44 -0000
@@ -10749,12 +10751,13 @@
 
 Many older shells (including the Bourne shell) implement here-documents
 inefficiently.  And some shells mishandle large here-documents: for
-example, Solaris @command{dtksh}, which is derived from Korn shell
-version M-12/28/93d, mishandles variable expansion that occurs on
-1024-byte buffer boundaries within a here-document.  Users can generally
-fix these problems by using a faster or more reliable shell, e.g., by
-using the command @samp{CONFIG_SHELL=/bin/bash /bin/bash ./configure} rather
-than plain @samp{./configure}.
+example, Solaris @command{dtksh} and the UnixWare Posix shell, which are
+derived from Korn shell version M-12/28/93d, mishandle braced variable
+expansion @address@hidden@}} that crosses a 1024- or 4096-byte buffer boundary
+within a here-document.  If the closing brace does not lie on the boundary,
+the failure is silent and the variable expansion will be empty, otherwise
+the shell will report a bad substitution.  This bug can usually be worked
+around by omitting the braces: @code{$var}.
 
 Some shells can be extremely inefficient when there are a lot of
 here-documents inside a single statement.  For instance if your