AC_C_CHAR_UNSIGNED is not strictly necessary.

* doc/autoconf.texi (C Compiler) <AC_C_CHAR_UNSIGNED>: Mention a
portable alternative to this macro.
* THANKS: Update.
Reported by Hallvard B Furuseth.

Signed-off-by: Eric Blake <ebb9@byu.net>

diff --git a/ChangeLog b/ChangeLog
index 155637b531ee247950c2f3c24c8c08f25016f4a6..ed7a91541e97bb2439c48ee1d7772b691c17e2a5 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,11 @@
 2008-08-06  Eric Blake  <ebb9@byu.net>
 
+       AC_C_CHAR_UNSIGNED is not strictly necessary.
+       * doc/autoconf.texi (C Compiler) <AC_C_CHAR_UNSIGNED>: Mention a
+       portable alternative to this macro.
+       * THANKS: Update.
+       Reported by Hallvard B Furuseth.
+
        Update some files from upstream.
        * GNUmakefile: Update.
        * build-aux/announce-gen: Likewise.

diff --git a/THANKS b/THANKS
index 912ec2c8bb50ded8a52c696476c5bf78e563a2c1..7b903a9f079a742023849eb76eee912bdf35453f 100644 (file)
--- a/THANKS
+++ b/THANKS
@@ -132,6 +132,7 @@ Guillermo Gomez             gomez@mi.uni-erlangen.de
 H. Merijn Brand             h.m.brand@hccnet.nl
 H. Peter Anvin              ?
 H.J. Lu                     hjl@gnu.org
+Hallvard B Furuseth         h.b.furuseth@usit.uio.no
 Hans Aberg                  haberg@math.su.se
 Hans Olsson                 Hans.Olsson@dna.lth.se
 Hans Ulrich Niedermann      hun@n-dimensional.de

diff --git a/doc/autoconf.texi b/doc/autoconf.texi
index b1b2a24aa0bbd13cfecba4854dcfc568508f4898..61cccca656cd0837c56acddac9b877da3abd45c3 100644 (file)
--- a/doc/autoconf.texi
+++ b/doc/autoconf.texi
@@ -6884,6 +6884,17 @@ if it accepts one of those, otherwise define @code{inline} to be empty.
 @cvindex __CHAR_UNSIGNED__
 If the C type @code{char} is unsigned, define @code{__CHAR_UNSIGNED__},
 unless the C compiler predefines it.
+
+These days, using this macro is not necessary.  The same information can
+be determined by this portable alternative, thus avoiding the use of
+preprocessor macros in the namespace reserved for the implementation.
+
+@example
+#include <limits.h>
+#if CHAR_MIN == 0
+# define CHAR_UNSIGNED 1
+#endif
+@end example
 @end defmac
 
 @defmac AC_C_STRINGIZE