New module 'hypotl'.

[gnulib.git] / m4 / logb.m4

diff --git a/m4/logb.m4 b/m4/logb.m4
index 4dadd17..f6d1555 100644 (file)
--- a/m4/logb.m4
+++ b/m4/logb.m4
@@ -1,5 +1,5 @@
-# logb.m4 serial 2
-dnl Copyright (C) 2010 Free Software Foundation, Inc.
+# logb.m4 serial 4
+dnl Copyright (C) 2010-2012 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
@@ -8,7 +8,7 @@ AC_DEFUN([gl_FUNC_LOGB],
 [
   AC_REQUIRE([gl_MATH_H_DEFAULTS])
   dnl Test whether logb() is declared.
-  AC_CHECK_DECLS([logb], , , [#include <math.h>])
+  AC_CHECK_DECLS([logb], , , [[#include <math.h>]])
   if test "$ac_cv_have_decl_logb" != yes; then
     HAVE_DECL_LOGB=0
   fi
@@ -20,7 +20,11 @@ AC_DEFUN([gl_FUNC_LOGB],
          # define __NO_MATH_INLINES 1 /* for glibc */
          #endif
          #include <math.h>
-         extern double logb (double x);
+         extern
+         #ifdef __cplusplus
+         "C"
+         #endif
+         double logb (double x);
          double x;]],
        [[x = logb(x);]])],
     [LOGB_LIBM=])
@@ -33,7 +37,11 @@ AC_DEFUN([gl_FUNC_LOGB],
            # define __NO_MATH_INLINES 1 /* for glibc */
            #endif
            #include <math.h>
-           extern double logb (double x);
+           extern
+           #ifdef __cplusplus
+           "C"
+           #endif
+           double logb (double x);
            double x;]],
          [[x = logb(x);]])],
       [LOGB_LIBM="-lm"])