* wcwidth.m4 (gl_FUNC_WCWIDTH): Simplify by using AC_CHECK_DECLS.

[gnulib.git] / m4 / stdbool.m4

diff --git a/m4/stdbool.m4 b/m4/stdbool.m4
index f37f27b..2204ecd 100644 (file)
--- a/m4/stdbool.m4
+++ b/m4/stdbool.m4
@@ -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];
@@ -74,7 +74,7 @@ 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__
+         #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
@@ -86,7 +86,10 @@ AC_DEFUN([AC_HEADER_STDBOOL],
              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.  */
+             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
@@ -98,9 +101,11 @@ AC_DEFUN([AC_HEADER_STDBOOL],
          _Bool *pq = &q;
        ],
        [
+         *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);
+                 + !m + !n + !o + !p + !q + !pq);
        ],
        [ac_cv_header_stdbool_h=yes],
        [ac_cv_header_stdbool_h=no])])