Known? 2.53a swallowing brackets it oughtn't

[Soren A]

Hello,

I am using GNU Autoconf 2.53a.
Platform: Cygwin (output of `uname -a':
CYGWIN_NT-4.0 CHERUBIC 1.3.10(0.51/3/2) 2002-02-25 11:14 i486 unknown).

I think I have found a bug in this autoconf release.

In a configure.ac, if I attempt to write a shell expression using any
tool that takes bracketed regexes like "grep '[0-9]'" or "case $Foo in
row[2-6] ) dostuff;; esac", autoconf eats the brackets and the output
configure script is faulty in that it doesn't faithfully reproduce the
logic I intended (I will get "grep '0-9'" and so on). 

As I understand it, I should definitely expect to have to hande brackets
with kid gloves (US idiom: "carefully") _inside_ an autoconf macro. This
case I am seeing is not inside any autoconf macro. It involves external
conditional logic in the configure.ac -- shell scripting -- "in-between"
any calls to autoconf macros that are in this configure.ac. Not "inside"
a call to (invocation of, reference to, whatever) an autoconf macro. 

Thus it is not expected behavior that I should have to worry about my
brackets in these instances becoming victims of subtle foul play, and at
the very minimum there would be a severe documentation bug/deficiency
here if this was considered "OK" behavior from autoconf but users aren't
alerted to be on guard for it. 

Any readers can feel very free to NOT reply in any way to this message
as I won't misrepresent myself by acting as if I am a mild-mannered
nice-guy supporter of GNU Autotools. I rather vociferously have NOT
been: 

  <address@hidden>
   "Where is Buffy when we need her!?!"

So I am not looking to make friends here. But I have been told that
instead of just growsing about how miserable Autotool'ed packages have
been making my life I should file bug reports, so I have just tried.
Now, back to my bottle. 

  Soren Andersen