changeset 16688:ff618f17a176

log2-ieee: Work around test failure on NetBSD 5.1 and Solaris 10. * m4/log2-ieee.m4: New file. * m4/log2.m4 (gl_FUNC_LOG2): If gl_FUNC_LOG2_IEEE is present, test whether log2 works with a minus zero argument. Replace it if not. * modules/log2-ieee (Files): Add m4/log2-ieee.m4. (configure.ac): Invoke gl_FUNC_LOG2_IEEE. * doc/posix-functions/log2.texi: Mention the log2-ieee module.
author Bruno Haible <bruno@clisp.org>
date Sun, 11 Mar 2012 22:12:34 +0100
parents 3df51d8317c0
children 749edfc2abd5
files ChangeLog doc/posix-functions/log2.texi m4/log2-ieee.m4 m4/log2.m4 modules/log2-ieee
diffstat 5 files changed, 88 insertions(+), 3 deletions(-) [+]
line wrap: on
line diff
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,13 @@
 2012-03-11  Bruno Haible  <bruno@clisp.org>
 
+	log2-ieee: Work around test failure on NetBSD 5.1 and Solaris 10.
+	* m4/log2-ieee.m4: New file.
+	* m4/log2.m4 (gl_FUNC_LOG2): If gl_FUNC_LOG2_IEEE is present, test
+	whether log2 works with a minus zero argument. Replace it if not.
+	* modules/log2-ieee (Files): Add m4/log2-ieee.m4.
+	(configure.ac): Invoke gl_FUNC_LOG2_IEEE.
+	* doc/posix-functions/log2.texi: Mention the log2-ieee module.
+
 	Tests for module 'log2l-ieee'.
 	* modules/log2l-ieee-tests: New file.
 	* tests/test-log2l-ieee.c: New file.
--- a/doc/posix-functions/log2.texi
+++ b/doc/posix-functions/log2.texi
@@ -4,9 +4,9 @@
 
 POSIX specification:@* @url{http://www.opengroup.org/onlinepubs/9699919799/functions/log2.html}
 
-Gnulib module: log2
+Gnulib module: log2 or log2-ieee
 
-Portability problems fixed by Gnulib:
+Portability problems fixed by either Gnulib module @code{log2} or @code{log2-ieee}:
 @itemize
 @item
 This function is missing on some platforms:
@@ -26,6 +26,13 @@
 Cygwin 1.7.9.
 @end itemize
 
+Portability problems fixed by Gnulib module @code{log2-ieee}:
+@itemize
+@item
+This function returns a wrong value for a negative argument on some platforms:
+NetBSD 5.1, Solaris 11 2011-11.
+@end itemize
+
 Portability problems not fixed by Gnulib:
 @itemize
 @end itemize
new file mode 100644
--- /dev/null
+++ b/m4/log2-ieee.m4
@@ -0,0 +1,15 @@
+# log2-ieee.m4 serial 1
+dnl Copyright (C) 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.
+
+dnl This macro is in a separate file (not in remainder.m4 and not inlined in the
+dnl module description), so that gl_FUNC_LOG2 can test whether 'aclocal' has
+dnl found uses of this macro.
+
+AC_DEFUN([gl_FUNC_LOG2_IEEE],
+[
+  m4_divert_text([INIT_PREPARE], [gl_log2_required=ieee])
+  AC_REQUIRE([gl_FUNC_LOG2])
+])
--- a/m4/log2.m4
+++ b/m4/log2.m4
@@ -1,4 +1,4 @@
-# log2.m4 serial 1
+# log2.m4 serial 2
 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,
@@ -6,6 +6,7 @@
 
 AC_DEFUN([gl_FUNC_LOG2],
 [
+  m4_divert_text([DEFAULTS], [gl_log2_required=plain])
   AC_REQUIRE([gl_MATH_H_DEFAULTS])
 
   dnl Persuade glibc <math.h> to declare log2().
@@ -33,6 +34,58 @@
       *yes) ;;
       *) REPLACE_LOG2=1 ;;
     esac
+
+    m4_ifdef([gl_FUNC_LOG2_IEEE], [
+      if test $gl_log2_required = ieee && test $REPLACE_LOG2 = 0; then
+        AC_CACHE_CHECK([whether log2 works according to ISO C 99 with IEC 60559],
+          [gl_cv_func_log2_ieee],
+          [
+            save_LIBS="$LIBS"
+            LIBS="$LIBS $LOG2_LIBM"
+            AC_RUN_IFELSE(
+              [AC_LANG_SOURCE([[
+#ifndef __NO_MATH_INLINES
+# define __NO_MATH_INLINES 1 /* for glibc */
+#endif
+#include <math.h>
+#ifndef log2 /* for Cygwin 1.7.x */
+extern
+#ifdef __cplusplus
+"C"
+#endif
+double log2 (double);
+#endif
+/* Compare two numbers with ==.
+   This is a separate function because IRIX 6.5 "cc -O" miscompiles an
+   'x == x' test.  */
+static int
+numeric_equal (double x, double y)
+{
+  return x == y;
+}
+static double dummy (double x) { return 0; }
+int main (int argc, char *argv[])
+{
+  double (*my_log2) (double) = argc ? log2 : dummy;
+  /* Test log2(negative).
+     This test fails on NetBSD 5.1 and Solaris 11 2011-11.  */
+  double y = my_log2 (-1.0);
+  if (numeric_equal (y, y))
+    return 1;
+  return 0;
+}
+              ]])],
+              [gl_cv_func_log2_ieee=yes],
+              [gl_cv_func_log2_ieee=no],
+              [gl_cv_func_log2_ieee="guessing no"])
+            LIBS="$save_LIBS"
+          ])
+        case "$gl_cv_func_log2_ieee" in
+          *yes) ;;
+          *) REPLACE_LOG2=1 ;;
+        esac
+      fi
+    ])
   else
     HAVE_LOG2=0
     HAVE_DECL_LOG2=0
--- a/modules/log2-ieee
+++ b/modules/log2-ieee
@@ -2,12 +2,14 @@
 log2() function according to ISO C 99 with IEC 60559.
 
 Files:
+m4/log2-ieee.m4
 
 Depends-on:
 log2
 fpieee
 
 configure.ac:
+gl_FUNC_LOG2_IEEE
 
 Makefile.am: