hypotl-ieee: Work around test failure on OSF/1 and native Windows.

[gnulib.git] / m4 / hypotl.m4

diff --git a/m4/hypotl.m4 b/m4/hypotl.m4
index 57b472f..424e0a1 100644 (file)
--- a/m4/hypotl.m4
+++ b/m4/hypotl.m4
@@ -1,4 +1,4 @@
-# hypotl.m4 serial 1
+# hypotl.m4 serial 2
 dnl Copyright (C) 2012 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -6,6 +6,7 @@ dnl with or without modifications, as long as this notice is preserved.
 
 AC_DEFUN([gl_FUNC_HYPOTL],
 [
+  m4_divert_text([DEFAULTS], [gl_hypotl_required=plain])
   AC_REQUIRE([gl_MATH_H_DEFAULTS])
   AC_REQUIRE([gl_FUNC_HYPOT])
 
@@ -17,8 +18,57 @@ AC_DEFUN([gl_FUNC_HYPOTL],
   LIBS="$save_LIBS"
   if test $ac_cv_func_hypotl = yes; then
     HYPOTL_LIBM="$HYPOT_LIBM"
+    m4_ifdef([gl_FUNC_HYPOTL_IEEE], [
+      if test $gl_hypotl_required = ieee && test $REPLACE_HYPOTL = 0; then
+        AC_CACHE_CHECK([whether hypotl works according to ISO C 99 with IEC 60559],
+          [gl_cv_func_hypotl_ieee],
+          [
+            save_LIBS="$LIBS"
+            LIBS="$LIBS $HYPOTL_LIBM"
+            AC_RUN_IFELSE(
+              [AC_LANG_SOURCE([[
+#ifndef __NO_MATH_INLINES
+# define __NO_MATH_INLINES 1 /* for glibc */
+#endif
+#include <math.h>
+/* Compare two numbers with ==.
+   This is a separate function because IRIX 6.5 "cc -O" miscompiles an
+   'x == x' test.  */
+static int
+numeric_equal (long double x, long double y)
+{
+  return x == y;
+}
+static long double dummy (long double x, long double y) { return 0; }
+long double zero;
+long double one = 1.0L;
+int main (int argc, char *argv[])
+{
+  long double (*my_hypotl) (long double, long double) = argc ? hypotl : dummy;
+  long double f;
+  /* Test hypotl(NaN,Infinity).
+     This test fails on OSF/1 5.1 and native Windows.  */
+  f = my_hypotl (zero / zero, one / zero);
+  if (!numeric_equal (f, f))
+    return 1;
+  return 0;
+}
+              ]])],
+              [gl_cv_func_hypotl_ieee=yes],
+              [gl_cv_func_hypotl_ieee=no],
+              [gl_cv_func_hypotl_ieee="guessing no"])
+            LIBS="$save_LIBS"
+          ])
+        case "$gl_cv_func_hypotl_ieee" in
+          *yes) ;;
+          *) REPLACE_HYPOTL=1 ;;
+        esac
+      fi
+    ])
   else
     HAVE_HYPOTL=0
+  fi
+  if test $HAVE_HYPOTL = 0 || test $REPLACE_HYPOTL = 1; then
     dnl Find libraries needed to link lib/hypotl.c.
     if test $HAVE_SAME_LONG_DOUBLE_AS_DOUBLE = 1; then
       HYPOTL_LIBM="$HYPOT_LIBM"