Merge commit 'a39d4083cab589d7cd6a13e8a4b8db8875261d75'

[gnulib.git] / m4 / copysignl.m4

diff --git a/m4/copysignl.m4 b/m4/copysignl.m4
index 4b5329f..a250a26 100644 (file)
--- a/m4/copysignl.m4
+++ b/m4/copysignl.m4
@@ -1,5 +1,5 @@
-# copysignl.m4 serial 1
-dnl Copyright (C) 2011 Free Software Foundation, Inc.
+# copysignl.m4 serial 3
+dnl Copyright (C) 2011-2014 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.
@@ -7,13 +7,22 @@ dnl with or without modifications, as long as this notice is preserved.
 AC_DEFUN([gl_FUNC_COPYSIGNL],
 [
   AC_REQUIRE([gl_MATH_H_DEFAULTS])
+  AC_REQUIRE([gl_LONG_DOUBLE_VS_DOUBLE])
+
+  dnl Persuade glibc <math.h> to declare copysignl().
+  AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
 
   dnl Determine COPYSIGNL_LIBM.
   gl_MATHFUNC([copysignl], [long double], [(long double, long double)])
   if test $gl_cv_func_copysignl_no_libm = no \
      && test $gl_cv_func_copysignl_in_libm = no; then
     HAVE_COPYSIGNL=0
-    COPYSIGNL_LIBM=
+    if test $HAVE_SAME_LONG_DOUBLE_AS_DOUBLE = 1; then
+      AC_REQUIRE([gl_FUNC_COPYSIGN])
+      COPYSIGNL_LIBM="$COPYSIGN_LIBM"
+    else
+      COPYSIGNL_LIBM=
+    fi
   fi
   AC_SUBST([COPYSIGNL_LIBM])
 ])