log10: Work around OSF/1 5.1 bug.

* lib/math.in.h (log10): New declaration.
* lib/log10.c: New file.
* m4/log10.m4 (gl_FUNC_LOG10_WORKS): New macro.
(gl_FUNC_LOG10): Invoke it. Set REPLACE_LOG10.
* m4/math_h.m4 (gl_MATH_H): Test whether log10 is declared.
(gl_MATH_H_DEFAULTS): Initialize GNULIB_LOG10, REPLACE_LOG10.
* modules/math (Makefile.am): Substitute GNULIB_LOG10, REPLACE_LOG10.
* modules/log10 (Files): Add lib/log10.c.
(Depends-on): Add math.
(configure.ac): If REPLACE_LOG10 is 1, compile an override.
* tests/test-math-c++.cc: Check the declaration of log10.
* doc/posix-functions/log10.texi: Mention the OSF/1 5.1 problem.

9 files changed, 129 insertions, 4 deletions

diff --git a/ChangeLog b/ChangeLog
index 45c41973a1..67191809fa 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,19 @@
+2012-04-01  Bruno Haible  <bruno@clisp.org>
+
+	log10: Work around OSF/1 5.1 bug.
+	* lib/math.in.h (log10): New declaration.
+	* lib/log10.c: New file.
+	* m4/log10.m4 (gl_FUNC_LOG10_WORKS): New macro.
+	(gl_FUNC_LOG10): Invoke it. Set REPLACE_LOG10.
+	* m4/math_h.m4 (gl_MATH_H): Test whether log10 is declared.
+	(gl_MATH_H_DEFAULTS): Initialize GNULIB_LOG10, REPLACE_LOG10.
+	* modules/math (Makefile.am): Substitute GNULIB_LOG10, REPLACE_LOG10.
+	* modules/log10 (Files): Add lib/log10.c.
+	(Depends-on): Add math.
+	(configure.ac): If REPLACE_LOG10 is 1, compile an override.
+	* tests/test-math-c++.cc: Check the declaration of log10.
+	* doc/posix-functions/log10.texi: Mention the OSF/1 5.1 problem.
+
 2012-03-31  Bruno Haible  <bruno@clisp.org>
 
 	log10l tests: More tests.
diff --git a/doc/posix-functions/log10.texi b/doc/posix-functions/log10.texi
index 0674fdb8e0..34936d13ea 100644
--- a/doc/posix-functions/log10.texi
+++ b/doc/posix-functions/log10.texi
@@ -8,6 +8,9 @@ Gnulib module: log10
 
 Portability problems fixed by Gnulib:
 @itemize
+@item
+This function returns a wrong value for a minus zero argument on some platforms:
+OSF/1 5.1.
 @end itemize
 
 Portability problems not fixed by Gnulib:
diff --git a/lib/log10.c b/lib/log10.c
new file mode 100644
index 0000000000..9e959b862d
--- /dev/null
+++ b/lib/log10.c
@@ -0,0 +1,31 @@
+/* Base 10 logarithmic function.
+   Copyright (C) 2012 Free Software Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+/* Specification.  */
+#include <math.h>
+
+double
+log10 (double x)
+#undef log10
+{
+  /* Work around the OSF/1 5.1 bug.  */
+  if (x == 0.0)
+    /* Return -Infinity.  */
+    return -1.0 / 0.0;
+  return log10 (x);
+}
diff --git a/lib/math.in.h b/lib/math.in.h
index 4b2ce87ac2..3a77922d3c 100644
--- a/lib/math.in.h
+++ b/lib/math.in.h
@@ -1205,6 +1205,26 @@ _GL_WARN_ON_USE (log10f, "log10f is unportable - "
 # endif
 #endif
 
+#if @GNULIB_LOG10@
+# if @REPLACE_LOG10@
+#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+#   undef log10
+#   define log10 rpl_log10
+#  endif
+_GL_FUNCDECL_RPL (log10, double, (double x));
+_GL_CXXALIAS_RPL (log10, double, (double x));
+# else
+_GL_CXXALIAS_SYS (log10, double, (double x));
+# endif
+_GL_CXXALIASWARN (log10);
+#elif defined GNULIB_POSIXCHECK
+# undef log10
+# if HAVE_RAW_DECL_LOG10
+_GL_WARN_ON_USE (log10, "log10 has portability problems - "
+                 "use gnulib module log10 for portability");
+# endif
+#endif
+
 #if @GNULIB_LOG10L@
 # if !@HAVE_LOG10L@ || !@HAVE_DECL_LOG10L@
 #  undef log10l
diff --git a/m4/log10.m4 b/m4/log10.m4
index 251c1c6363..ab066cc071 100644
--- a/m4/log10.m4
+++ b/m4/log10.m4
@@ -1,4 +1,4 @@
-# log10.m4 serial 1
+# log10.m4 serial 2
 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,
@@ -6,6 +6,49 @@ dnl with or without modifications, as long as this notice is preserved.
 
 AC_DEFUN([gl_FUNC_LOG10],
 [
+  AC_REQUIRE([gl_MATH_H_DEFAULTS])
+
   dnl Determine LOG10_LIBM.
   gl_COMMON_DOUBLE_MATHFUNC([log10])
+
+  save_LIBS="$LIBS"
+  LIBS="$LIBS $LOG10_LIBM"
+  gl_FUNC_LOG10_WORKS
+  LIBS="$save_LIBS"
+  case "$gl_cv_func_log10_works" in
+    *yes) ;;
+    *) REPLACE_LOG10=1 ;;
+  esac
+])
+
+dnl Test whether log10() works.
+dnl On OSF/1 5.1, log10(-0.0) is NaN.
+AC_DEFUN([gl_FUNC_LOG10_WORKS],
+[
+  AC_REQUIRE([AC_PROG_CC])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+  AC_CACHE_CHECK([whether log10 works], [gl_cv_func_log10_works],
+    [
+      AC_RUN_IFELSE(
+        [AC_LANG_SOURCE([[
+#include <math.h>
+volatile double x;
+double y;
+int main ()
+{
+  x = -0.0;
+  y = log10 (x);
+  if (!(y + y == y))
+    return 1;
+  return 0;
+}
+]])],
+        [gl_cv_func_log10_works=yes],
+        [gl_cv_func_log10_works=no],
+        [case "$host_os" in
+           osf*) gl_cv_func_log10_works="guessing no";;
+           *)    gl_cv_func_log10_works="guessing yes";;
+         esac
+        ])
+    ])
 ])
diff --git a/m4/math_h.m4 b/m4/math_h.m4
index ff1654ec7f..2fe2ecef69 100644
--- a/m4/math_h.m4
+++ b/m4/math_h.m4
@@ -1,4 +1,4 @@
-# math_h.m4 serial 104
+# math_h.m4 serial 105
 dnl Copyright (C) 2007-2012 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -45,7 +45,7 @@ AC_DEFUN([gl_MATH_H],
      fabsf fabsl floorf floorl fma fmaf fmal
      fmod fmodf fmodl frexpf frexpl hypotf hypotl
      ldexpf ldexpl
-     logb log logf logl log10f log10l log1p log1pf log1pl log2 log2f log2l
+     logb log logf logl log10 log10f log10l log1p log1pf log1pl log2 log2f log2l
      modf modff modfl powf
      remainder remainderf remainderl
      rint rintf rintl round roundf roundl sinf sinl sinhf sqrtf sqrtl
@@ -119,6 +119,7 @@ AC_DEFUN([gl_MATH_H_DEFAULTS],
   GNULIB_LOG=0;        AC_SUBST([GNULIB_LOG])
   GNULIB_LOGF=0;       AC_SUBST([GNULIB_LOGF])
   GNULIB_LOGL=0;       AC_SUBST([GNULIB_LOGL])
+  GNULIB_LOG10=0;      AC_SUBST([GNULIB_LOG10])
   GNULIB_LOG10F=0;     AC_SUBST([GNULIB_LOG10F])
   GNULIB_LOG10L=0;     AC_SUBST([GNULIB_LOG10L])
   GNULIB_LOG1P=0;      AC_SUBST([GNULIB_LOG1P])
@@ -277,6 +278,7 @@ AC_DEFUN([gl_MATH_H_DEFAULTS],
   REPLACE_LOG=0;               AC_SUBST([REPLACE_LOG])
   REPLACE_LOGF=0;              AC_SUBST([REPLACE_LOGF])
   REPLACE_LOGL=0;              AC_SUBST([REPLACE_LOGL])
+  REPLACE_LOG10=0;             AC_SUBST([REPLACE_LOG10])
   REPLACE_LOG1P=0;             AC_SUBST([REPLACE_LOG1P])
   REPLACE_LOG1PF=0;            AC_SUBST([REPLACE_LOG1PF])
   REPLACE_LOG1PL=0;            AC_SUBST([REPLACE_LOG1PL])
diff --git a/modules/log10 b/modules/log10
index 4385288451..3918d1f659 100644
--- a/modules/log10
+++ b/modules/log10
@@ -2,13 +2,19 @@ Description:
 log10() function: base 10 logarithmic function.
 
 Files:
+lib/log10.c
 m4/log10.m4
 m4/mathfunc.m4
 
 Depends-on:
+math
 
 configure.ac:
 gl_FUNC_LOG10
+if test $REPLACE_LOG10 = 1; then
+  AC_LIBOBJ([log10])
+fi
+gl_MATH_MODULE_INDICATOR([log10])
 
 Makefile.am:
 
diff --git a/modules/math b/modules/math
index 51db89e0a6..ceb77884af 100644
--- a/modules/math
+++ b/modules/math
@@ -84,6 +84,7 @@ math.h: math.in.h $(top_builddir)/config.status $(CXXDEFS_H) $(ARG_NONNULL_H) $(
 	      -e 's/@''GNULIB_LOG''@/$(GNULIB_LOG)/g' \
 	      -e 's/@''GNULIB_LOGF''@/$(GNULIB_LOGF)/g' \
 	      -e 's/@''GNULIB_LOGL''@/$(GNULIB_LOGL)/g' \
+	      -e 's/@''GNULIB_LOG10''@/$(GNULIB_LOG10)/g' \
 	      -e 's/@''GNULIB_LOG10F''@/$(GNULIB_LOG10F)/g' \
 	      -e 's/@''GNULIB_LOG10L''@/$(GNULIB_LOG10L)/g' \
 	      -e 's/@''GNULIB_LOG1P''@/$(GNULIB_LOG1P)/g' \
@@ -244,6 +245,7 @@ math.h: math.in.h $(top_builddir)/config.status $(CXXDEFS_H) $(ARG_NONNULL_H) $(
 	      -e 's|@''REPLACE_LOG''@|$(REPLACE_LOG)|g' \
 	      -e 's|@''REPLACE_LOGF''@|$(REPLACE_LOGF)|g' \
 	      -e 's|@''REPLACE_LOGL''@|$(REPLACE_LOGL)|g' \
+	      -e 's|@''REPLACE_LOG10''@|$(REPLACE_LOG10)|g' \
 	      -e 's|@''REPLACE_LOG1P''@|$(REPLACE_LOG1P)|g' \
 	      -e 's|@''REPLACE_LOG1PF''@|$(REPLACE_LOG1PF)|g' \
 	      -e 's|@''REPLACE_LOG1PL''@|$(REPLACE_LOG1PL)|g' \
diff --git a/tests/test-math-c++.cc b/tests/test-math-c++.cc
index 9caa9511e6..b6df6595c4 100644
--- a/tests/test-math-c++.cc
+++ b/tests/test-math-c++.cc
@@ -210,7 +210,9 @@ SIGNATURE_CHECK (GNULIB_NAMESPACE::ldexpl, long double, (long double, int));
 
 //SIGNATURE_CHECK (GNULIB_NAMESPACE::lgamma, double, (double));
 
-//SIGNATURE_CHECK (GNULIB_NAMESPACE::log10, double, (double));
+#if GNULIB_TEST_LOG10
+SIGNATURE_CHECK (GNULIB_NAMESPACE::log10, double, (double));
+#endif
 #if GNULIB_TEST_LOG10L
 SIGNATURE_CHECK (GNULIB_NAMESPACE::log10l, long double, (long double));
 #endif