I notice that AC_MINGW32 and friends don't cooperate with AC_CANONICAL_HOST. A configure.in
AC_INIT AC_CANONICAL_HOST AC_MINGW32 AC_CYGWIN AC_EMXOS2 processed with autoconf gives configure.in:3: warning: AC_CANONICAL_HOST invoked multiple times configure.in:4: warning: AC_CANONICAL_HOST invoked multiple times configure.in:5: warning: AC_CANONICAL_HOST invoked multiple times I see it was a deliberate change not to use AC_REQUIRE in those, perhaps something else is wanted. (I know these macros are obsolete, I only struck this running a recent autoconf over a guile configure.in.)
