--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,16 @@
+2012-02-29  Bruno Haible  <bruno@clisp.org>
+
+	cbrtf: Work around bug in IRIX 6.5 system function.
+	* lib/math.in.h (cbrtf): Override if REPLACE_CBRTF is 1.
+	* m4/cbrtf.m4 (gl_FUNC_CBRTF_WORKS): New macro.
+	(gl_FUNC_CBRTF): Invoke it. Set REPLACE_CBRTF to 1 if cbrtf() does not
+	work.
+	* m4/math_h.m4 (gl_MATH_H_DEFAULTS): Initialize REPLACE_CBRTF.
+	* modules/math (Makefile.am): Substitute REPLACE_CBRTF.
+	* modules/cbrtf (configure.ac): Consider REPLACE_CBRTF.
+	(Depends-on): Update conditions.
+	* doc/posix-functions/cbrtf.texi: Mention the IRIX 6.5 problem.
+
 2012-02-29  Bruno Haible  <bruno@clisp.org>
 
 	Tests for module 'cbrtl'.

--- a/doc/posix-functions/cbrtf.texi
+++ b/doc/posix-functions/cbrtf.texi
@@ -14,6 +14,9 @@
 @item
 This function is not declared on some platforms:
 IRIX 6.5.
+@item
+This function returns a wrong value for a minus zero on some platforms:
+IRIX 6.5.
 @end itemize
 
 Portability problems not fixed by Gnulib:

--- a/lib/math.in.h
+++ b/lib/math.in.h
@@ -289,10 +289,19 @@
 
 
 #if @GNULIB_CBRTF@
-# if !@HAVE_DECL_CBRTF@
+# if @REPLACE_CBRTF@
+#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+#   undef cbrtf
+#   define cbrtf rpl_cbrtf
+#  endif
+_GL_FUNCDECL_RPL (cbrtf, float, (float x));
+_GL_CXXALIAS_RPL (cbrtf, float, (float x));
+# else
+#  if !@HAVE_DECL_CBRTF@
 _GL_FUNCDECL_SYS (cbrtf, float, (float x));
+#  endif
+_GL_CXXALIAS_SYS (cbrtf, float, (float x));
 # endif
-_GL_CXXALIAS_SYS (cbrtf, float, (float x));
 _GL_CXXALIASWARN (cbrtf);
 #elif defined GNULIB_POSIXCHECK
 # undef cbrtf

--- a/m4/cbrtf.m4
+++ b/m4/cbrtf.m4
@@ -1,4 +1,4 @@
-# cbrtf.m4 serial 1
+# cbrtf.m4 serial 2
 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,
@@ -20,9 +20,19 @@
     dnl Also check whether it's declared.
     dnl IRIX 6.5 has cbrtf() in libm but doesn't declare it in <math.h>.
     AC_CHECK_DECL([cbrtf], , [HAVE_DECL_CBRTF=0], [[#include <math.h>]])
+    save_LIBS="$LIBS"
+    LIBS="$LIBS $CBRTF_LIBM"
+    gl_FUNC_CBRTF_WORKS
+    LIBS="$save_LIBS"
+    case "$gl_cv_func_cbrtf_works" in
+      *yes) ;;
+      *) REPLACE_CBRTF=1 ;;
+    esac
   else
     HAVE_CBRTF=0
     HAVE_DECL_CBRTF=0
+  fi
+  if test $HAVE_CBRTF = 0 || test $REPLACE_CBRTF = 1; then
     dnl Find libraries needed to link lib/cbrtf.c.
     AC_REQUIRE([gl_FUNC_FABSF])
     AC_REQUIRE([gl_FUNC_FREXPF])
@@ -46,3 +56,41 @@
   fi
   AC_SUBST([CBRTF_LIBM])
 ])
+
+dnl Test whether cbrtf() works.
+dnl It returns wrong values on IRIX 6.5.
+AC_DEFUN([gl_FUNC_CBRTF_WORKS],
+[
+  AC_REQUIRE([AC_PROG_CC])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+  AC_CACHE_CHECK([whether cbrtf works], [gl_cv_func_cbrtf_works],
+    [
+      AC_RUN_IFELSE(
+        [AC_LANG_SOURCE([[
+#include <math.h>
+volatile float x;
+volatile float y;
+int main ()
+{
+  extern
+  #ifdef __cplusplus
+  "C"
+  #endif
+  float cbrtf (float);
+  /* This test fails on IRIX 6.5.  */
+  x = - 0.0f;
+  y = cbrtf (x);
+  if (!(y == 0.0f))
+    return 1;
+  return 0;
+}
+]])],
+        [gl_cv_func_cbrtf_works=yes],
+        [gl_cv_func_cbrtf_works=no],
+        [case "$host_os" in
+           irix*) gl_cv_func_cbrtf_works="guessing no";;
+           *)     gl_cv_func_cbrtf_works="guessing yes";;
+         esac
+        ])
+    ])
+])

--- a/m4/math_h.m4
+++ b/m4/math_h.m4
@@ -1,4 +1,4 @@
-# math_h.m4 serial 77
+# math_h.m4 serial 78
 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,
@@ -216,6 +216,7 @@
   HAVE_DECL_TRUNC=1;           AC_SUBST([HAVE_DECL_TRUNC])
   HAVE_DECL_TRUNCF=1;          AC_SUBST([HAVE_DECL_TRUNCF])
   HAVE_DECL_TRUNCL=1;          AC_SUBST([HAVE_DECL_TRUNCL])
+  REPLACE_CBRTF=0;             AC_SUBST([REPLACE_CBRTF])
   REPLACE_CEIL=0;              AC_SUBST([REPLACE_CEIL])
   REPLACE_CEILF=0;             AC_SUBST([REPLACE_CEILF])
   REPLACE_CEILL=0;             AC_SUBST([REPLACE_CEILL])

--- a/modules/cbrtf
+++ b/modules/cbrtf
@@ -9,14 +9,14 @@
 
 Depends-on:
 math
-isfinite        [test $HAVE_CBRTF = 0]
-fabsf           [test $HAVE_CBRTF = 0]
-frexpf          [test $HAVE_CBRTF = 0]
-ldexpf          [test $HAVE_CBRTF = 0]
+isfinite        [test $HAVE_CBRTF = 0 || test $REPLACE_CBRTF = 1]
+fabsf           [test $HAVE_CBRTF = 0 || test $REPLACE_CBRTF = 1]
+frexpf          [test $HAVE_CBRTF = 0 || test $REPLACE_CBRTF = 1]
+ldexpf          [test $HAVE_CBRTF = 0 || test $REPLACE_CBRTF = 1]
 
 configure.ac:
 gl_FUNC_CBRTF
-if test $HAVE_CBRTF = 0; then
+if test $HAVE_CBRTF = 0 || test $REPLACE_CBRTF = 1; then
   AC_LIBOBJ([cbrtf])
 fi
 gl_MATH_MODULE_INDICATOR([cbrtf])

--- a/modules/math
+++ b/modules/math
@@ -185,7 +185,8 @@
 	      -e 's|@''HAVE_DECL_TRUNCF''@|$(HAVE_DECL_TRUNCF)|g' \
 	      -e 's|@''HAVE_DECL_TRUNCL''@|$(HAVE_DECL_TRUNCL)|g' \
 	  | \
-	  sed -e 's|@''REPLACE_CEIL''@|$(REPLACE_CEIL)|g' \
+	  sed -e 's|@''REPLACE_CBRTF''@|$(REPLACE_CBRTF)|g' \
+	      -e 's|@''REPLACE_CEIL''@|$(REPLACE_CEIL)|g' \
 	      -e 's|@''REPLACE_CEILF''@|$(REPLACE_CEILF)|g' \
 	      -e 's|@''REPLACE_CEILL''@|$(REPLACE_CEILL)|g' \
 	      -e 's|@''REPLACE_FABSL''@|$(REPLACE_FABSL)|g' \