--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,19 @@
 2012-03-08  Bruno Haible  <bruno@clisp.org>
 
+	exp2l-ieee: Work around test failure on OpenBSD 4.9 and IRIX 6.5.
+	* m4/exp2l-ieee.m4: New file.
+	* m4/exp2l.m4 (gl_FUNC_EXP2L): If gl_FUNC_EXP2L_IEEE is present,
+	test whether exp2l works with a NaN argument and with a negative
+	infinity argument. Replace it if not.
+	* lib/math.in.h (exp2l): Override if REPLACE_EXP2L is 1.
+	* m4/math_h.m4 (gl_MATH_H_DEFAULTS): Initialize REPLACE_EXP2L.
+	* modules/math (Makefile.am): Substitute REPLACE_EXP2L.
+	* modules/exp2l (configure.ac): Consider REPLACE_EXP2L.
+	(Depends-on): Update conditions.
+	* modules/exp2l-ieee (Files): Add m4/exp2l-ieee.m4.
+	(configure.ac): Invoke gl_FUNC_EXP2L_IEEE.
+	* doc/posix-functions/exp2l.texi: Mention the exp2l-ieee module.
+
 	Tests for module 'exp2l-ieee'.
 	* modules/exp2l-ieee-tests: New file.
 	* tests/test-exp2l-ieee.c: New file.

--- a/doc/posix-functions/exp2l.texi
+++ b/doc/posix-functions/exp2l.texi
@@ -4,9 +4,9 @@
 
 POSIX specification:@* @url{http://www.opengroup.org/onlinepubs/9699919799/functions/exp2l.html}
 
-Gnulib module: exp2l
+Gnulib module: exp2l or exp2l-ieee
 
-Portability problems fixed by Gnulib:
+Portability problems fixed by either Gnulib module @code{exp2l} or @code{exp2l-ieee}:
 @itemize
 @item
 This function is missing on some platforms:
@@ -16,6 +16,16 @@
 IRIX 6.5.
 @end itemize
 
+Portability problems fixed by Gnulib module @code{exp2l-ieee}:
+@itemize
+@item
+This function returns a wrong value for a NaN argument on some platforms:
+OpenBSD 4.9.
+@item
+This function returns a wrong value for a negative infinity argument on some platforms:
+IRIX 6.5.
+@end itemize
+
 Portability problems not fixed by Gnulib:
 @itemize
 @end itemize

--- a/lib/math.in.h
+++ b/lib/math.in.h
@@ -570,11 +570,20 @@
 #endif
 
 #if @GNULIB_EXP2L@
-# if !@HAVE_DECL_EXP2L@
-#  undef exp2l
+# if @REPLACE_EXP2L@
+#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+#   undef exp2l
+#   define exp2l rpl_exp2l
+#  endif
+_GL_FUNCDECL_RPL (exp2l, long double, (long double x));
+_GL_CXXALIAS_RPL (exp2l, long double, (long double x));
+# else
+#  if !@HAVE_DECL_EXP2L@
+#   undef exp2l
 _GL_FUNCDECL_SYS (exp2l, long double, (long double x));
+#  endif
+_GL_CXXALIAS_SYS (exp2l, long double, (long double x));
 # endif
-_GL_CXXALIAS_SYS (exp2l, long double, (long double x));
 _GL_CXXALIASWARN (exp2l);
 #elif defined GNULIB_POSIXCHECK
 # undef exp2l

new file mode 100644
--- /dev/null
+++ b/m4/exp2l-ieee.m4
@@ -0,0 +1,15 @@
+# exp2l-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 exp2l.m4 and not inlined in the
+dnl module description), so that gl_FUNC_EXP2L can test whether 'aclocal' has
+dnl found uses of this macro.
+
+AC_DEFUN([gl_FUNC_EXP2L_IEEE],
+[
+  m4_divert_text([INIT_PREPARE], [gl_exp2l_required=ieee])
+  AC_REQUIRE([gl_FUNC_EXP2L])
+])

--- a/m4/exp2l.m4
+++ b/m4/exp2l.m4
@@ -1,4 +1,4 @@
-# exp2l.m4 serial 1
+# exp2l.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_EXP2L],
 [
+  m4_divert_text([DEFAULTS], [gl_exp2l_required=plain])
   AC_REQUIRE([gl_MATH_H_DEFAULTS])
   AC_REQUIRE([gl_LONG_DOUBLE_VS_DOUBLE])
   AC_REQUIRE([gl_FUNC_EXP2])
@@ -25,9 +26,56 @@
     dnl Also check whether it's declared.
     dnl IRIX 6.5 has exp2l() in libm but doesn't declare it in <math.h>.
     AC_CHECK_DECL([exp2l], , [HAVE_DECL_EXP2L=0], [[#include <math.h>]])
+    m4_ifdef([gl_FUNC_EXP2L_IEEE], [
+      if test $gl_exp2l_required = ieee && test $REPLACE_EXP2L = 0; then
+        AC_CACHE_CHECK([whether exp2l works according to ISO C 99 with IEC 60559],
+          [gl_cv_func_exp2l_ieee],
+          [
+            save_LIBS="$LIBS"
+            LIBS="$LIBS $EXP2L_LIBM"
+            AC_RUN_IFELSE(
+              [AC_LANG_SOURCE([[
+#ifndef __NO_MATH_INLINES
+# define __NO_MATH_INLINES 1 /* for glibc */
+#endif
+#include <math.h>
+#undef exp2l
+extern
+#ifdef __cplusplus
+"C"
+#endif
+long double exp2l (long double);
+static long double dummy (long double x) { return 0; }
+static long double zero;
+int main (int argc, char *argv[])
+{
+  long double (*my_exp2l) (long double) = argc ? exp2l : dummy;
+  int result = 0;
+  /* This test fails on OpenBSD 4.9, where exp2l(NaN) = 0.0.  */
+  if (exp2l (zero / zero) == 0.0L)
+    result |= 1;
+  /* This test fails on IRIX 6.5, where exp2l(-Inf) = 1.0.  */
+  if (!(exp2l (-1.0L / zero) == 0.0L))
+    result |= 2;
+  return result;
+}
+              ]])],
+              [gl_cv_func_exp2l_ieee=yes],
+              [gl_cv_func_exp2l_ieee=no],
+              [gl_cv_func_exp2l_ieee="guessing no"])
+            LIBS="$save_LIBS"
+          ])
+        case "$gl_cv_func_exp2l_ieee" in
+          *yes) ;;
+          *) REPLACE_EXP2L=1 ;;
+        esac
+      fi
+    ])
   else
     HAVE_EXP2L=0
     HAVE_DECL_EXP2L=0
+  fi
+  if test $HAVE_EXP2L = 0 || test $REPLACE_EXP2L = 1; then
     dnl Find libraries needed to link lib/exp2l.c.
     if test $HAVE_SAME_LONG_DOUBLE_AS_DOUBLE = 1; then
       EXP2L_LIBM="$EXP2_LIBM"

--- a/m4/math_h.m4
+++ b/m4/math_h.m4
@@ -1,4 +1,4 @@
-# math_h.m4 serial 91
+# math_h.m4 serial 92
 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,
@@ -237,6 +237,7 @@
   REPLACE_EXPM1=0;             AC_SUBST([REPLACE_EXPM1])
   REPLACE_EXPM1F=0;            AC_SUBST([REPLACE_EXPM1F])
   REPLACE_EXP2=0;              AC_SUBST([REPLACE_EXP2])
+  REPLACE_EXP2L=0;             AC_SUBST([REPLACE_EXP2L])
   REPLACE_FABSL=0;             AC_SUBST([REPLACE_FABSL])
   REPLACE_FLOOR=0;             AC_SUBST([REPLACE_FLOOR])
   REPLACE_FLOORF=0;            AC_SUBST([REPLACE_FLOORF])

--- a/modules/exp2l
+++ b/modules/exp2l
@@ -9,15 +9,15 @@
 Depends-on:
 math
 extensions
-exp2            [test $HAVE_EXP2L = 0 && test $HAVE_SAME_LONG_DOUBLE_AS_DOUBLE = 1]
-float           [test $HAVE_EXP2L = 0 && test $HAVE_SAME_LONG_DOUBLE_AS_DOUBLE = 0]
-isnanl          [test $HAVE_EXP2L = 0 && test $HAVE_SAME_LONG_DOUBLE_AS_DOUBLE = 0]
-roundl          [test $HAVE_EXP2L = 0 && test $HAVE_SAME_LONG_DOUBLE_AS_DOUBLE = 0]
-ldexpl          [test $HAVE_EXP2L = 0 && test $HAVE_SAME_LONG_DOUBLE_AS_DOUBLE = 0]
+exp2            [{ test $HAVE_EXP2L = 0 || test $REPLACE_EXP2L = 1; } && test $HAVE_SAME_LONG_DOUBLE_AS_DOUBLE = 1]
+float           [{ test $HAVE_EXP2L = 0 || test $REPLACE_EXP2L = 1; } && test $HAVE_SAME_LONG_DOUBLE_AS_DOUBLE = 0]
+isnanl          [{ test $HAVE_EXP2L = 0 || test $REPLACE_EXP2L = 1; } && test $HAVE_SAME_LONG_DOUBLE_AS_DOUBLE = 0]
+roundl          [{ test $HAVE_EXP2L = 0 || test $REPLACE_EXP2L = 1; } && test $HAVE_SAME_LONG_DOUBLE_AS_DOUBLE = 0]
+ldexpl          [{ test $HAVE_EXP2L = 0 || test $REPLACE_EXP2L = 1; } && test $HAVE_SAME_LONG_DOUBLE_AS_DOUBLE = 0]
 
 configure.ac:
 gl_FUNC_EXP2L
-if test $HAVE_EXP2L = 0; then
+if test $HAVE_EXP2L = 0 || test $REPLACE_EXP2L = 1; then
   AC_LIBOBJ([exp2l])
   AC_LIBOBJ([expl-table])
 fi

--- a/modules/exp2l-ieee
+++ b/modules/exp2l-ieee
@@ -2,12 +2,14 @@
 exp2l() function according to ISO C 99 with IEC 60559.
 
 Files:
+m4/exp2l-ieee.m4
 
 Depends-on:
 exp2l
 fpieee
 
 configure.ac:
+gl_FUNC_EXP2L_IEEE
 
 Makefile.am:
 

--- a/modules/math
+++ b/modules/math
@@ -205,6 +205,7 @@
 	      -e 's|@''REPLACE_EXPM1''@|$(REPLACE_EXPM1)|g' \
 	      -e 's|@''REPLACE_EXPM1F''@|$(REPLACE_EXPM1F)|g' \
 	      -e 's|@''REPLACE_EXP2''@|$(REPLACE_EXP2)|g' \
+	      -e 's|@''REPLACE_EXP2L''@|$(REPLACE_EXP2L)|g' \
 	      -e 's|@''REPLACE_FABSL''@|$(REPLACE_FABSL)|g' \
 	      -e 's|@''REPLACE_FLOOR''@|$(REPLACE_FLOOR)|g' \
 	      -e 's|@''REPLACE_FLOORF''@|$(REPLACE_FLOORF)|g' \