AC_CYGWIN

[Patrick Welche]

I had a go at compiling glib on a non-linux platform (!) and found

configure.in:300: warning: AC_CANONICAL_HOST invoked multiple times 

Line 106 is AC_CANONICAL_HOST, and line 300 is AC_CYGWIN.

I found the definition of AC_CYGWIN in lib/autoconf/specific.m4:

# AC_CYGWIN
# ---------
# Check for Cygwin.  This is a way to set the right value for  
# EXEEXT.
AU_DEFUN([AC_CYGWIN],
[AC_CANONICAL_HOST
AC_DIAGNOSE([obsolete],
        [$0 is obsolete: use AC_CANONICAL_HOST and $host_os])dnl
case $host_os in  
  *cygwin* ) CYGWIN=yes;;
     * ) CYGWIN=no;;
esac
])# AC_CYGWIN


Several things I don't understand: google brought up an email which
esentially said "Don't use AC_REQUIRE inside AU_DEFUN", but then how
do you say "Only run AC_CANONICAL_HOST if it hasn't been run before".
Also, AU_DEFUN (OLD-MACRO, IMPLEMENTATION, [MESSAGE]), so why use
AC_DIAGNOSE instead of [MESSAGE]?

(This on NetBSD-1.6T/i386, cvs autotools,perl 5.8.0)

Cheers,

Patrick