X-Git-Url: https://erislabs.net/gitweb/?a=blobdiff_plain;f=m4%2Fhypot.m4;h=05e6c5fed44ac0e8e4bce65758f812196d3c7af5;hb=03ea4328ae1ea7e985f7fd9a42ebf77bc64bd47c;hp=b8faf8893214713c0bc4cdb73eb173f85c350522;hpb=fb88b295e090486496c869d44a7b47ee8cbc4071;p=gnulib.git

diff --git a/m4/hypot.m4 b/m4/hypot.m4
index b8faf8893..05e6c5fed 100644
--- a/m4/hypot.m4
+++ b/m4/hypot.m4
@@ -1,4 +1,4 @@
-# hypot.m4 serial 1
+# hypot.m4 serial 4
 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 +6,95 @@ dnl with or without modifications, as long as this notice is preserved.
 
 AC_DEFUN([gl_FUNC_HYPOT],
 [
+  m4_divert_text([DEFAULTS], [gl_hypot_required=plain])
+  AC_REQUIRE([gl_MATH_H_DEFAULTS])
+
+  dnl Persuade glibc <math.h> to declare hypot().
+  AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
+
   dnl Determine HYPOT_LIBM.
   gl_COMMON_DOUBLE_MATHFUNC([hypot])
+
+  m4_ifdef([gl_FUNC_HYPOT_IEEE], [
+    if test $gl_hypot_required = ieee && test $REPLACE_HYPOT = 0; then
+      AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+      AC_CACHE_CHECK([whether hypot works according to ISO C 99 with IEC 60559],
+        [gl_cv_func_hypot_ieee],
+        [
+          save_LIBS="$LIBS"
+          LIBS="$LIBS $HYPOT_LIBM"
+          AC_RUN_IFELSE(
+            [AC_LANG_SOURCE([[
+#ifndef __NO_MATH_INLINES
+# define __NO_MATH_INLINES 1 /* for glibc */
+#endif
+#include <math.h>
+/* Compare two numbers with ==.
+   This is a separate function because IRIX 6.5 "cc -O" miscompiles an
+   'x == x' test.  */
+static int
+numeric_equal (double x, double y)
+{
+  return x == y;
+}
+static double dummy (double x, double y) { return 0; }
+double zero;
+double one = 1.0;
+int main (int argc, char *argv[])
+{
+  double (*my_hypot) (double, double) = argc ? hypot : dummy;
+  double f;
+  /* Test hypot(NaN,Infinity).
+     This test fails on OSF/1 5.1 and native Windows.  */
+  f = my_hypot (zero / zero, one / zero);
+  if (!numeric_equal (f, f))
+    return 1;
+  return 0;
+}
+            ]])],
+            [gl_cv_func_hypot_ieee=yes],
+            [gl_cv_func_hypot_ieee=no],
+            [case "$host_os" in
+                       # Guess yes on glibc systems.
+               *-gnu*) gl_cv_func_hypot_ieee="guessing yes" ;;
+                       # If we don't know, assume the worst.
+               *)      gl_cv_func_hypot_ieee="guessing no" ;;
+             esac
+            ])
+          LIBS="$save_LIBS"
+        ])
+      case "$gl_cv_func_hypot_ieee" in
+        *yes) ;;
+        *) REPLACE_HYPOT=1 ;;
+      esac
+    fi
+  ])
+  if test $REPLACE_HYPOT = 1; then
+    dnl Find libraries needed to link lib/hypot.c.
+    AC_REQUIRE([gl_FUNC_FABS])
+    AC_REQUIRE([gl_FUNC_FREXP])
+    AC_REQUIRE([gl_FUNC_LDEXP])
+    AC_REQUIRE([gl_FUNC_SQRT])
+    HYPOT_LIBM=
+    dnl Append $FABS_LIBM to HYPOT_LIBM, avoiding gratuitous duplicates.
+    case " $HYPOT_LIBM " in
+      *" $FABS_LIBM "*) ;;
+      *) HYPOT_LIBM="$HYPOT_LIBM $FABS_LIBM" ;;
+    esac
+    dnl Append $FREXP_LIBM to HYPOT_LIBM, avoiding gratuitous duplicates.
+    case " $HYPOT_LIBM " in
+      *" $FREXP_LIBM "*) ;;
+      *) HYPOT_LIBM="$HYPOT_LIBM $FREXP_LIBM" ;;
+    esac
+    dnl Append $LDEXP_LIBM to HYPOT_LIBM, avoiding gratuitous duplicates.
+    case " $HYPOT_LIBM " in
+      *" $LDEXP_LIBM "*) ;;
+      *) HYPOT_LIBM="$HYPOT_LIBM $LDEXP_LIBM" ;;
+    esac
+    dnl Append $SQRT_LIBM to HYPOT_LIBM, avoiding gratuitous duplicates.
+    case " $HYPOT_LIBM " in
+      *" $SQRT_LIBM "*) ;;
+      *) HYPOT_LIBM="$HYPOT_LIBM $SQRT_LIBM" ;;
+    esac
+  fi
 ])