X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=m4%2Fhypotf.m4;h=aec739b085c85621c890e4bbb6cc0a8fae93f973;hb=8866a241ddbf4a459347b7147e325f539e4c07fe;hp=c6185a543939bfa5c6fc4131e4269b4b4580f85b;hpb=b3f31eeaa29521c15f6d5523a50c3061faf4384b;p=gnulib.git

diff --git a/m4/hypotf.m4 b/m4/hypotf.m4
index c6185a543..aec739b08 100644
--- a/m4/hypotf.m4
+++ b/m4/hypotf.m4
@@ -1,5 +1,5 @@
-# hypotf.m4 serial 2
-dnl Copyright (C) 2012 Free Software Foundation, Inc.
+# hypotf.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.
@@ -10,6 +10,9 @@ AC_DEFUN([gl_FUNC_HYPOTF],
   AC_REQUIRE([gl_MATH_H_DEFAULTS])
   AC_REQUIRE([gl_FUNC_HYPOT])
 
+  dnl Persuade glibc <math.h> to declare hypotf().
+  AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
+
   dnl Test whether hypotf() exists. Assume that hypotf(), if it exists, is
   dnl defined in the same library as hypot().
   save_LIBS="$LIBS"
@@ -28,6 +31,7 @@ AC_DEFUN([gl_FUNC_HYPOTF],
     esac
     m4_ifdef([gl_FUNC_HYPOTF_IEEE], [
       if test $gl_hypotf_required = ieee && test $REPLACE_HYPOTF = 0; then
+        AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
         AC_CACHE_CHECK([whether hypotf works according to ISO C 99 with IEC 60559],
           [gl_cv_func_hypotf_ieee],
           [
@@ -64,7 +68,13 @@ int main (int argc, char *argv[])
               ]])],
               [gl_cv_func_hypotf_ieee=yes],
               [gl_cv_func_hypotf_ieee=no],
-              [gl_cv_func_hypotf_ieee="guessing no"])
+              [case "$host_os" in
+                         # Guess yes on glibc systems.
+                 *-gnu*) gl_cv_func_hypotf_ieee="guessing yes" ;;
+                         # If we don't know, assume the worst.
+                 *)      gl_cv_func_hypotf_ieee="guessing no" ;;
+               esac
+              ])
             LIBS="$save_LIBS"
           ])
         case "$gl_cv_func_hypotf_ieee" in