X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;ds=sidebyside;f=m4%2Fcopysignf.m4;h=293bf456132ecf0aeb727aeb87b46ca031980055;hb=108828a0e95d3c4e89ff4f38fe4b39ae6218792e;hp=f706009a3d3b55cf0e710a378f2d3226e219fc6b;hpb=1602f0afed21be664fcf5c42d59db07cc22c56d6;p=gnulib.git

diff --git a/m4/copysignf.m4 b/m4/copysignf.m4
index f706009a3..293bf4561 100644
--- a/m4/copysignf.m4
+++ b/m4/copysignf.m4
@@ -1,4 +1,4 @@
-# copysignf.m4 serial 1
+# copysignf.m4 serial 3
 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,
@@ -8,11 +8,26 @@ AC_DEFUN([gl_FUNC_COPYSIGNF],
 [
   AC_REQUIRE([gl_MATH_H_DEFAULTS])
 
+  dnl Persuade glibc <math.h> to declare copysignf().
+  AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
+
   dnl Determine COPYSIGNF_LIBM.
-  gl_MATHFUNC([copysignf], [float], [(float, float)])
-  if test $gl_cv_func_copysignf_no_libm = no \
-     && test $gl_cv_func_copysignf_in_libm = no; then
+  gl_MATHFUNC([copysignf], [float], [(float, float)],
+    [extern
+     #ifdef __cplusplus
+     "C"
+     #endif
+     float copysignf (float, float);
+    ])
+  if test $gl_cv_func_copysignf_no_libm = yes \
+     || test $gl_cv_func_copysignf_in_libm = yes; then
+    HAVE_COPYSIGNF=1
+    dnl Also check whether it's declared.
+    dnl IRIX 6.5 has copysignf() in libm but doesn't declare it in <math.h>.
+    AC_CHECK_DECL([copysignf], , [HAVE_DECL_COPYSIGNF=0], [[#include <math.h>]])
+  else
     HAVE_COPYSIGNF=0
+    HAVE_DECL_COPYSIGNF=0
     COPYSIGNF_LIBM=
   fi
   AC_SUBST([COPYSIGNF_LIBM])