X-Git-Url: https://erislabs.net/gitweb/?a=blobdiff_plain;f=m4%2Fhypot.m4;h=2ae3be7a9b2ca6b3de30acfa2cbfd0c672d3e3a0;hb=da8054d48dc22e1c051db54049e005d51a006e69;hp=1837a01a0ecf7627e1a5dbe9372ee8063a41713d;hpb=9fb732a430dbc21f0502b77e76ec68d13f8b8f39;p=gnulib.git

diff --git a/m4/hypot.m4 b/m4/hypot.m4
index 1837a01a0..2ae3be7a9 100644
--- a/m4/hypot.m4
+++ b/m4/hypot.m4
@@ -1,5 +1,5 @@
-# hypot.m4 serial 2
-dnl Copyright (C) 2012 Free Software Foundation, Inc.
+# hypot.m4 serial 4
+dnl Copyright (C) 2012-2013 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.
@@ -9,11 +9,15 @@ 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 $REPLACE_HYPOT = 0; then
+      AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
       AC_CACHE_CHECK([whether hypot works according to ISO C 99 with IEC 60559],
         [gl_cv_func_hypot_ieee],
         [
@@ -50,7 +54,13 @@ int main (int argc, char *argv[])
             ]])],
             [gl_cv_func_hypot_ieee=yes],
             [gl_cv_func_hypot_ieee=no],
-            [gl_cv_func_hypot_ieee="guessing no"])
+            [case "$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