Re: Directory name completion blocks when it shouldn't

[Chris Moore]

Richard Stallman <address@hidden> writes:

> On the other hand, cd does use read-directory-name.
> So this appears to be a bug in the completion routines themselves.

read-directory-name uses read-file-name with PREDICATE set to
'file-directory-p

read-file-name uses read-file-name-internal

read-file-name-internal ignores the value of PREDICATE if ACTION is
nil (ACTION is t if we are listing possible completions, and nil if
are actually doing the completion)

When we are doing the completion, read-file-name-internal calls
file_name_completion in dired.c to actually do it.
file_name_completion doesn't have any code to complete only
directories, but it does honour the value of
completion-ignored-extensions.  If we temporarily bind
completion-ignored-extensions to include the empty string, it will
ignore all files, but not directories.

So here's a possible fix:

------------------------------------------------------------------------
--- lisp/files.el       2006-12-01 14:27:47.000000000 +0100
+++ /tmp/files.el       2006-12-08 15:49:50.000000000 +0100
@@ -576,11 +576,12 @@
 the value of `default-directory'."
   (unless dir
     (setq dir default-directory))
-  (read-file-name prompt dir (or default-dirname
-                                (if initial (expand-file-name initial dir)
-                                  dir))
-                 mustmatch initial
-                 'file-directory-p))
+  (let ((completion-ignored-extensions (cons "" 
completion-ignored-extensions)))
+    (read-file-name prompt dir (or default-dirname
+                                  (if initial (expand-file-name initial dir)
+                                    dir))
+                   mustmatch initial
+                   'file-directory-p)))
 
 
 (defun pwd ()
------------------------------------------------------------------------

And a test case:

$ mkdir -p /tmp/dir/subdir
$ touch /tmp/dir/sub.txt
$ emacs
M-x cd RET /tmp/dir/s TAB

Before applying the patch, TAB will complete only up to "/tmp/dir/sub".  With
the patch it will complete to "/tmp/dir/subdir/".