configure.in: declare a requirement for at least autoconf 2.50

On Debian/Ubuntu systems, if autoconf version 2.13 is installed,
autoconf will try to automatically figure out whether autoconf 2.13 or
something more modern is required (since the autoconf maintainers,
curses be upon them, didn't bother to maintain compatibility between
autoconf 2.13 and 2.50).  Unfortunately, the hueristics aren't
perfect, and although the configure.in file looks superficially like
it will be compatible with autoconf 2.13, it isn't.  You will end up
with a number of very subtle compilation failures if you use autoconf
2.13.

So declare a requirement for autoconf 2.50 using AC_PREREQ(2.50).

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Christoph Hellwig <hch@lst.de>

diff --git a/configure.in b/configure.in
index 10c4c611ee6a1228987dc3d62974dea0b826abbb..664c0e93bc88bbc218a66004a63eb45b04740efd 100644 (file)
--- a/configure.in
+++ b/configure.in
@@ -1,4 +1,5 @@
 AC_INIT(include/libxfs.h)
+AC_PREREQ(2.50)
 AC_CONFIG_AUX_DIR([.])
 AC_CONFIG_MACRO_DIR([m4])
 AC_CONFIG_HEADER(include/platform_defs.h)