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.

3 files changed, 19 insertions, 8 deletions

diff --git a/doc/lispref/files.texi b/doc/lispref/files.texi
index f4678ddd846..068cf054437 100644
--- a/doc/lispref/files.texi
+++ b/doc/lispref/files.texi
@@ -1567,13 +1567,16 @@ For compatibility, @var{predicate} can also be one of the symbols
 a list of one or more of these symbols.
 @end defun
 
-@defun executable-find program
+@defun executable-find program &optional remote
 This function searches for the executable file of the named
 @var{program} and returns the absolute file name of the executable,
 including its file-name extensions, if any.  It returns @code{nil} if
-the file is not found.  The functions searches in all the directories
+the file is not found.  The function searches in all the directories
 in @code{exec-path}, and tries all the file-name extensions in
 @code{exec-suffixes} (@pxref{Subprocess Creation}).
+
+If @var{remote} is non-@code{nil}, and @code{default-directory} is a
+remote directory, @var{program} is searched on the respective remote host.
 @end defun
 
 @node Changing Files
@@ -3137,8 +3140,8 @@ first, before handlers for jobs such as remote file access.
 @code{directory-file-name},
 @code{directory-files},
 @code{directory-files-and-attributes},
-@code{dired-compress-file}, @code{dired-uncache},@*
-@code{expand-file-name},
+@code{dired-compress-file}, @code{dired-uncache},
+@code{exec-path}, @code{expand-file-name},@*
 @code{file-accessible-directory-p},
 @code{file-acl},
 @code{file-attributes},
@@ -3195,7 +3198,7 @@ first, before handlers for jobs such as remote file access.
 @code{directory-files},
 @code{directory-files-and-at@discretionary{}{}{}tributes},
 @code{dired-compress-file}, @code{dired-uncache},
-@code{expand-file-name},
+@code{exec-path}, @code{expand-file-name},
 @code{file-accessible-direc@discretionary{}{}{}tory-p},
 @code{file-acl},
 @code{file-attributes},
diff --git a/doc/lispref/processes.texi b/doc/lispref/processes.texi
index 3e26f577982..f78d8485e4e 100644
--- a/doc/lispref/processes.texi
+++ b/doc/lispref/processes.texi
@@ -177,6 +177,14 @@ before starting Emacs.  Trying to modify @code{exec-path}
 independently of @env{PATH} can lead to confusing results.
 @end defopt
 
+@defun exec-path
+The function @code{exec-path} is an extension of the respective
+variable.  If @code{default-directory} indicates a remote directory,
+it returns a list of directories used for searching programs on the
+respective remote host.  In case of a local @code{default-directory},
+the function returns just the value of the variable @code{exec-path}.
+@end defun
+
 @node Shell Arguments
 @section Shell Arguments
 @cindex arguments for shell commands
diff --git a/doc/misc/tramp.texi b/doc/misc/tramp.texi
index 420fef7164c..a9de1fddc66 100644
--- a/doc/misc/tramp.texi
+++ b/doc/misc/tramp.texi
@@ -1816,9 +1816,9 @@ shell supports the login argument @samp{-l}.
 @end defopt
 
 When remote search paths are changed, local @value{tramp} caches must
-be recomputed.  To force @value{tramp} to recompute afresh, exit
-Emacs, remove the persistent file (@pxref{Connection caching}), and
-restart Emacs.
+be recomputed.  To force @value{tramp} to recompute afresh, call
+@kbd{M-x tramp-cleanup-this-connection @key{RET}} or friends
+(@pxref{Cleanup remote connections}).
 
 
 @node Remote shell setup