Implement command completion in remote shells. (Bug#31704)

* doc/lispref/files.texi (Locating Files): Describe optional
argument REMOTE of `executable-find'.
(Magic File Names): Add `exec-path'.

* doc/lispref/processes.texi (Subprocess Creation): Describe
function `exec-path'.

* doc/misc/tramp.texi (Remote programs): Explain refresh of search
paths by `tramp-cleanup-this-connection'.

* etc/NEWS: Mention 'exec-path' and 'executable-find'.

* lisp/files.el (exec-path): New defun.
(executable-find): Add optional argument REMOTE.

* lisp/shell.el (shell-completion-vars): Set `comint-file-name-prefix'.
(shell--command-completion-data): Use `(exec-path)'.  (Bug#31704)

* lisp/net/ange-ftp.el (exec-path):
* lisp/net/tramp.el (tramp-file-name-for-operation):
* lisp/net/tramp-adb.el (tramp-adb-file-name-handler-alist):
* lisp/net/tramp-archive.el (tramp-archive-file-name-handler-alist):
* lisp/net/tramp-gvfs.el (tramp-gvfs-file-name-handler-alist):
* lisp/net/tramp-sh.el (tramp-sh-file-name-handler-alist):
* lisp/net/tramp-smb.el (tramp-smb-file-name-handler-alist)
<exec-path>: Add handler.

* lisp/net/tramp-adb.el (tramp-adb-handle-exec-path): New defun.
(tramp-adb-maybe-open-connection): Do not set "remote-path"
connection property.

* lisp/net/tramp-compat.el (tramp-compat-exec-path): New defun.

* lisp/net/tramp-sh.el (tramp-sh-handle-exec-path): New defun.

* lisp/net/tramp.el (tramp-eshell-directory-change): Use it.

* test/lisp/net/tramp-archive-tests.el
(tramp-archive-test38-make-nearby-temp-file)
(tramp-archive-test41-file-system-info)
(tramp-archive-test43-auto-load)
(tramp-archive-test43-delay-load): Rename.

* test/lisp/net/tramp-tests.el (tramp-test34-exec-path): New test.
(tramp-test36-make-auto-save-file-name)
(tramp-test37-find-backup-file-name)
(tramp-test38-make-nearby-temp-file)
(tramp-test39-special-characters)
(tramp-test39-special-characters-with-stat)
(tramp-test39-special-characters-with-perl)
(tramp-test39-special-characters-with-ls, tramp-test40-utf8)
(tramp-test40-utf8-with-stat, tramp-test40-utf8-with-perl)
(tramp-test40-utf8-with-ls, tramp-test41-file-system-info)
(tramp-test42-asynchronous-requests, tramp-test43-auto-load)
(tramp-test43-delay-load, tramp-test43-recursive-load)
(tramp-test43-remote-load-path, tramp-test44-unload): Rename.

1 files changed, 25 insertions, 5 deletions

diff --git a/lisp/files.el b/lisp/files.el
index c4a68d04407..d0804b000a6 100644
--- a/lisp/files.el
+++ b/lisp/files.el
@@ -1024,13 +1024,33 @@ customize the variable `user-emacs-directory-warning'."
 					errtype user-emacs-directory)))))
        bestname))))
 
+(defun exec-path ()
+  "List of directories to search programs to run in remote subprocesses.
+The remote host is identified by `default-directory'.  For remote
+hosts which do not support subprocesses, this returns `nil'.
+If `default-directory' is a local directory, the value of the variable
+`exec-path' is returned."
+  (let ((handler (find-file-name-handler default-directory 'exec-path)))
+    (if handler
+	(funcall handler 'exec-path)
+      exec-path)))
 
-(defun executable-find (command)
+(defun executable-find (command &optional remote)
   "Search for COMMAND in `exec-path' and return the absolute file name.
-Return nil if COMMAND is not found anywhere in `exec-path'."
-  ;; Use 1 rather than file-executable-p to better match the behavior of
-  ;; call-process.
-  (locate-file command exec-path exec-suffixes 1))
+Return nil if COMMAND is not found anywhere in `exec-path'.  If
+REMOTE is non-nil, search on the remote host indicated by
+`default-directory' instead."
+  (if (and remote (file-remote-p default-directory))
+      (let ((res (locate-file
+	          command
+	          (mapcar
+	           (lambda (x) (concat (file-remote-p default-directory) x))
+	           (exec-path))
+	          exec-suffixes 'file-executable-p)))
+        (when (stringp res) (file-local-name res)))
+    ;; Use 1 rather than file-executable-p to better match the
+    ;; behavior of call-process.
+    (locate-file command exec-path exec-suffixes 1)))
 
 (defun load-library (library)
   "Load the Emacs Lisp library named LIBRARY.