--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,10 @@
 2011-06-06  Eric Blake  <eblake@redhat.com>
 
+	canonicalize-lgpl: work around AIX realpath bug
+	* m4/canonicalize.m4 (gl_FUNC_REALPATH_WORKS): Expose AIX bug.
+	* doc/posix-functions/realpath.texi (realpath): Document it.
+	Reported by Bruno Haible.
+
 	strerror: work around FreeBSD bug
 	* lib/strerror.c (strerror): Special case 0.
 	Reported by Bruno Haible.

--- a/doc/posix-functions/realpath.texi
+++ b/doc/posix-functions/realpath.texi
@@ -27,6 +27,9 @@
 This function fails to recognize non-directories followed @samp{..} on
 some platforms:
 cygwin.
+@item
+This function misbehaves on consecutive slashes on some platforms:
+AIX 7.
 @end itemize
 
 Portability problems not fixed by Gnulib:

--- a/m4/canonicalize.m4
+++ b/m4/canonicalize.m4
@@ -1,4 +1,4 @@
-# canonicalize.m4 serial 19
+# canonicalize.m4 serial 20
 
 dnl Copyright (C) 2003-2007, 2009-2011 Free Software Foundation, Inc.
 
@@ -62,10 +62,12 @@
   AC_CHECK_FUNCS_ONCE([realpath])
   AC_CACHE_CHECK([whether realpath works], [gl_cv_func_realpath_works], [
     touch conftest.a
+    mkdir conftest.d
     AC_RUN_IFELSE([
       AC_LANG_PROGRAM([[
         ]GL_NOCRASH[
         #include <stdlib.h>
+        #include <string.h>
       ]], [[
         int result = 0;
         {
@@ -83,10 +85,17 @@
           if (name != NULL)
             result |= 4;
         }
+        {
+          char *name1 = realpath (".", NULL);
+          char *name2 = realpath ("conftest.d//./..", NULL);
+          if (strcmp (name1, name2) != 0)
+            result |= 8;
+        }
         return result;
       ]])
     ], [gl_cv_func_realpath_works=yes], [gl_cv_func_realpath_works=no],
        [gl_cv_func_realpath_works="guessing no"])
+    rm -Rf conftest.a conftest.d
   ])
   if test "$gl_cv_func_realpath_works" = yes; then
     AC_DEFINE([FUNC_REALPATH_WORKS], [1], [Define to 1 if realpath()