X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=m4%2Fstdbool.m4;h=2204ecd98405be59e1a8ef52d6fbd464f61552f7;hb=53a0d02424cfcde73015ce469bd01a5bc51ed337;hp=922a00258ee03299cb8cc9463d7c37e88a6cc7b1;hpb=94c929ecbd19082f4001fb3a33b5a85bd80d7749;p=gnulib.git

diff --git a/m4/stdbool.m4 b/m4/stdbool.m4
index 922a00258..2204ecd98 100644
--- a/m4/stdbool.m4
+++ b/m4/stdbool.m4
@@ -1,6 +1,6 @@
 # Check for stdbool.h that conforms to C99.
 
-dnl Copyright (C) 2002-2005 Free Software Foundation, Inc.
+dnl Copyright (C) 2002-2006 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
@@ -64,9 +64,9 @@ AC_DEFUN([AC_HEADER_STDBOOL],
 	  char a[true == 1 ? 1 : -1];
 	  char b[false == 0 ? 1 : -1];
 	  char c[__bool_true_false_are_defined == 1 ? 1 : -1];
-	  char d[(bool) -0.5 == true ? 1 : -1];
+	  char d[(bool) 0.5 == true ? 1 : -1];
 	  bool e = &s;
-	  char f[(_Bool) -0.0 == false ? 1 : -1];
+	  char f[(_Bool) 0.0 == false ? 1 : -1];
 	  char g[true];
 	  char h[sizeof (_Bool)];
 	  char i[sizeof s.t];
@@ -74,10 +74,38 @@ AC_DEFUN([AC_HEADER_STDBOOL],
 	  _Bool n[m];
 	  char o[sizeof n == m * sizeof n[0] ? 1 : -1];
 	  char p[-1 - (_Bool) 0 < 0 && -1 - (bool) 0 < 0 ? 1 : -1];
+	  #if defined __xlc__ || defined __GNUC__
+	   /* Catch a bug in IBM AIX xlc compiler version 6.0.0.0
+	      reported by James Lemley on 2005-10-05; see
+	      http://lists.gnu.org/archive/html/bug-coreutils/2005-10/msg00086.html
+	      This test is not quite right, since xlc is allowed to
+	      reject this program, as the initializer for xlcbug is
+	      not one of the forms that C requires support for.
+	      However, doing the test right would require a run-time
+	      test, and that would make cross-compilation harder.
+	      Let us hope that IBM fixes the xlc bug, and also adds
+	      support for this kind of constant expression.  In the
+	      meantime, this test will reject xlc, which is OK, since
+	      our stdbool.h substitute should suffice.  We also test
+	      this with GCC, where it should work, to detect more
+	      quickly whether someone messes up the test in the
+	      future.  */
+	   char digs[] = "0123456789";
+	   int xlcbug = 1 / (&(digs + 5)[-2 + (bool) 1] == &digs[4] ? 1 : -1);
+	  #endif
+	  /* Catch a bug in an HP-UX C compiler.  See
+	     http://gcc.gnu.org/ml/gcc-patches/2003-12/msg02303.html
+	     http://lists.gnu.org/archive/html/bug-coreutils/2005-11/msg00161.html
+	   */
+	  _Bool q = true;
+	  _Bool *pq = &q;
 	],
 	[
-	  return (!a + !b + !c + !d + !e + !f + !g + !h + !i + !j + !k + !l
-		  + !m + !n + !o + !p);
+	  *pq |= q;
+	  *pq |= ! q;
+	  /* Refer to every declared value, to avoid compiler optimizations.  */
+	  return (!a + !b + !c + !d + !e + !f + !g + !h + !i + !!j + !k + !!l
+		  + !m + !n + !o + !p + !q + !pq);
 	],
 	[ac_cv_header_stdbool_h=yes],
 	[ac_cv_header_stdbool_h=no])])