X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=m4%2Ftanf.m4;h=030abe95df04272f646478164a0f9260953dcdd8;hb=270e2d3e2966d9a5bc16dd0b367b71740b8994d5;hp=7ecbe81e77acf638307adc6d080596aee57a5b99;hpb=1602f0afed21be664fcf5c42d59db07cc22c56d6;p=gnulib.git

diff --git a/m4/tanf.m4 b/m4/tanf.m4
index 7ecbe81e7..030abe95d 100644
--- a/m4/tanf.m4
+++ b/m4/tanf.m4
@@ -1,4 +1,4 @@
-# tanf.m4 serial 1
+# tanf.m4 serial 2
 dnl Copyright (C) 2011-2012 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -9,6 +9,9 @@ AC_DEFUN([gl_FUNC_TANF],
   AC_REQUIRE([gl_MATH_H_DEFAULTS])
   AC_REQUIRE([gl_FUNC_TAN])
 
+  dnl Persuade glibc <math.h> to declare tanf().
+  AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
+
   dnl Test whether tanf() exists. Assume that tanf(), if it exists, is
   dnl defined in the same library as tan().
   save_LIBS="$LIBS"