Changeset 3640 for trunk/m4/yat_cxx11.m4

Timestamp:

May 3, 2017, 2:55:07 AM (6 years ago)

Author:

Peter

Message:

use std::log2 when available

File:

• trunk/m4/yat_cxx11.m4 (modified) (3 diffs)

trunk/m4/yat_cxx11.m4

@@ -1 +1 @@
 ## $Id$
 #
-# serial 2  (yat 0.15)
+# serial 3  (yat 0.15)
 #
 # see http://www.gnu.org/software/automake/manual/automake.html#Serials
@@ -12 +12 @@
 # DESCRIPTION
 #
-#   Test whether $CXX supports rvalues
+#   Test whether $CXX supports rvalues and other cxx11 features
 #
 # LAST MODIFICATION
@@ -82 +82 @@
 ]) # YAT_CXX_RVALUE
 
+
+# YAT_CXX_LOG2([action-if-found], [action-if-not-found])
+#
+# Test whether $CXX supports std::log2. If not, try turning on support
+# with a number of different switches. If a successful switch is found
+# invoke shell action-if-found; else issue action-if-not-found.
+AC_DEFUN([YAT_CXX_LOG2],
+[
+YAT_CXX_TRY_CXX11([log2], [ dnl header
+  @%:@include <cmath>
+  void foo(double x);
+  ],[ dnl body
+  double x = std::log2(3.14);
+  foo(x);
+  ], [# action
+  $1
+  ], [ # action if not found
+  $2
+  ])
+]) # YAT_CXX_RVALUE
+
+
 # YAT_CXX_TRY_CXX11([feature], [header], [body], [action-if-found],
 #                   [action-if-not-found])