AC_C_BACKSLASH_A

[Akim Demaille]

I'm installing the following patch.  Given that I greatly prefer a
simple interface, if you agree, I'd rather see this macro become
internal, and be called by AC_PROG_CC.  Or AC_PROG_CC_STDC.  I don't
like new macros :(

Index: ChangeLog
from  Akim Demaille  <address@hidden>

        * lib/autoconf/c.m4 (AC_C_BACKSLASH_A): New.
        * doc/autoconf.texi (C Compiler): Adjust.

Index: NEWS
===================================================================
RCS file: /cvsroot/autoconf/autoconf/NEWS,v
retrieving revision 1.246
diff -u -u -r1.246 NEWS
--- NEWS 7 Jun 2002 09:30:24 -0000 1.246
+++ NEWS 16 Jul 2002 13:29:44 -0000
@@ -23,8 +23,10 @@
 - AC_PROG_F77 default search no longer includes cf77 and cfg77.
 
 - New macros
-  AC_CONFIG_LIBOBJ_DIR, AC_GNU_SOURCE, AC_PROG_EGREP, AC_PROG_FGREP,
-  AC_REPLACE_FNMATCH, AC_FUNC_FNMATCH_GNU, AC_TYPE_MBSTATE_T.
+
+  AC_C_BACKSLASH_A, AC_CONFIG_LIBOBJ_DIR, AC_GNU_SOURCE,
+  AC_PROG_EGREP, AC_PROG_FGREP, AC_REPLACE_FNMATCH,
+  AC_FUNC_FNMATCH_GNU, AC_TYPE_MBSTATE_T.
 
 - AC_FUNC_GETLOADAVG
   looks for getloadavg.c in the CONFIG_LIBOBJ_DIR.
Index: doc/autoconf.texi
===================================================================
RCS file: /cvsroot/autoconf/autoconf/doc/autoconf.texi,v
retrieving revision 1.637
diff -u -u -r1.637 autoconf.texi
--- doc/autoconf.texi 9 Jul 2002 17:01:38 -0000 1.637
+++ doc/autoconf.texi 16 Jul 2002 13:31:13 -0000
@@ -4895,6 +4895,12 @@
 @code{AC_TRY_COMPILE} (@pxref{Examining Syntax}) or @code{AC_TRY_RUN}
 (@pxref{Run Time})
 
address@hidden AC_C_BACKSLASH_A
address@hidden HAVE_C_BACKSLASH_A
+Define @samp{HAVE_C_BACKSLASH_A} to 1 if the C compiler understands
address@hidden
address@hidden defmac
+
 @defmac AC_C_BIGENDIAN (@ovar{action-if-true}, @ovar{action-if-false}, 
@ovar{action-if-unknown})
 @acindex C_BIGENDIAN
 @cvindex WORDS_BIGENDIAN
Index: lib/autoconf/c.m4
===================================================================
RCS file: /cvsroot/autoconf/autoconf/lib/autoconf/c.m4,v
retrieving revision 1.165
diff -u -u -r1.165 c.m4
--- lib/autoconf/c.m4 7 Jun 2002 10:04:28 -0000 1.165
+++ lib/autoconf/c.m4 16 Jul 2002 13:31:18 -0000
@@ -793,6 +793,29 @@
 AU_DEFUN([AC_PROG_CC_STDC], [])
 
 
+# AC_C_BACKSLASH_A
+# ----------------
+AC_DEFUN([AC_C_BACKSLASH_A],
+[
+  AC_CACHE_CHECK([whether backslash-a works in strings], ac_cv_c_backslash_a,
+   [AC_COMPILE_IFELSE([AC_LANG_PROGRAM([],
+     [[
+#if '\a' == 'a'
+      syntax error;
+#endif
+      char buf['\a' == 'a' ? -1 : 1];
+      buf[0] = '\a';
+      return buf[0] != "\a"[0];
+     ]])],
+     [ac_cv_c_backslash_a=yes],
+     [ac_cv_c_backslash_a=no])])
+  if test $ac_cv_c_backslash_a = yes; then
+    AC_DEFINE(HAVE_C_BACKSLASH_A, 1,
+      [Define if backslash-a works in C strings.])
+  fi
+])
+
+
 # AC_C_CROSS
 # ----------
 # Has been merged into AC_PROG_CC.