math: Ensure declarations of math functions.

[gnulib.git] / m4 / hypotf.m4

diff --git a/m4/hypotf.m4 b/m4/hypotf.m4
index c6185a5..b4ebe9e 100644 (file)
--- a/m4/hypotf.m4
+++ b/m4/hypotf.m4
@@ -1,4 +1,4 @@
-# hypotf.m4 serial 2
+# hypotf.m4 serial 3
 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,
@@ -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"