Improve parsing example.

* doc/m4.texinfo (Input processing): Double-quote argument to
translit, for robustness.
* THANKS: Update.
Reported by Chris Penev.

Signed-off-by: Eric Blake <eblake@redhat.com>
(cherry picked from commit b4f66285d8252196e1b4c6acf55eda3c1118e580)

3 files changed, 18 insertions, 6 deletions

diff --git a/ChangeLog b/ChangeLog
index bf196aa2..12ccadfc 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2010-02-24  Eric Blake  <eblake@redhat.com>
+
+	Improve parsing example.
+	* doc/m4.texinfo (Input processing): Double-quote argument to
+	translit, for robustness.
+	* THANKS: Update.
+	Reported by Chris Penev.
+
 2010-01-29  Eric Blake  <ebb9@byu.net>
 
 	Document upcoming release.
diff --git a/THANKS b/THANKS
index 3512369f..7bd8b0a1 100644
--- a/THANKS
+++ b/THANKS
@@ -33,6 +33,7 @@ Bruno Haible            bruno@clisp.org
 Cesar Strauss           cestrauss@gmail.com
 Charles Wilson          cygwin@cwilson.fastmail.fm
 Chris McGuire           chris@wso.net
+Chris Penev             xpenev@gmail.com
 Damian Menscher         menscher@uiuc.edu
 Dan Jacobson            jidanni@jidanni.org
 Daniel Richard G.       skunk@iskunk.org
diff --git a/doc/m4.texinfo b/doc/m4.texinfo
index 2d4a81b9..fa0c6fda 100644
--- a/doc/m4.texinfo
+++ b/doc/m4.texinfo
@@ -1392,13 +1392,15 @@ whitespace so that less whitespace is output (which, although harmless
 to shell scripts, can be visually unappealing), and fixes the quoting
 issues so that the capitalization occurs when the macro
 @samp{gl_STRING_MODULE_INDICATOR} is invoked, rather then when it is
-defined.
+defined.  It also adds another layer of quoting to the first argument of
+@code{translit}, to ensure that the output will be rescanned as a string
+rather than a potential uppercase macro name needing further expansion.
 
 @example
 changequote([,])dnl
 define([gl_STRING_MODULE_INDICATOR],
   [dnl comment
-  GNULIB_[]translit([$1], [a-z], [A-Z])=1dnl
+  GNULIB_[]translit([[$1]], [a-z], [A-Z])=1dnl
 ])dnl
   gl_STRING_MODULE_INDICATOR([strcase])
 @result{}    GNULIB_STRCASE=1
@@ -1407,7 +1409,7 @@ define([gl_STRING_MODULE_INDICATOR],
 The parsing of the first line is unchanged.  The second line sees the
 name of the macro to define, then sees the discarded @samp{@key{NL}}
 and two spaces, as before.  But this time, the next token is
-@samp{[dnl comment@key{NL}@ @ GNULIB_[]translit([$1], [a-z],
+@samp{[dnl comment@key{NL}@ @ GNULIB_[]translit([[$1]], [a-z],
 [A-Z])=1dnl@key{NL}]}, which includes nested quotes, followed by
 @samp{)} to end the macro definition and @samp{dnl} to skip the
 newline.  No early expansion of @code{translit} occurs, so the entire
@@ -1424,10 +1426,11 @@ output literally.  The token @samp{[]} is an empty string, so it does
 not affect output.  Then the token @samp{translit} is encountered.
 
 This time, the arguments to @code{translit} are parsed as @samp{(},
-@samp{[strcase]}, @samp{,}, @samp{ }, @samp{[a-z]}, @samp{,}, @samp{ },
+@samp{[[strcase]]}, @samp{,}, @samp{ }, @samp{[a-z]}, @samp{,}, @samp{ },
 @samp{[A-Z]}, and @samp{)}.  The two spaces are discarded, and the
-translit results in the desired result @samp{STRCASE}.  This is
-rescanned, but since it is not a macro name, it is output literally.
+translit results in the desired result @samp{[STRCASE]}.  This is
+rescanned, but since it is a string, the quotes are stripped and the
+only output is a literal @samp{STRCASE}.
 Then the scanner sees @samp{=} and @samp{1}, which are output
 literally, followed by @samp{dnl} which discards the rest of the
 definition of @code{gl_STRING_MODULE_INDICATOR}.  The newline at the