Some minor Tramp changes

* lisp/net/tramp-adb.el (tramp-adb-handle-make-process):
Fix error message.

* lisp/net/tramp-cache.el (tramp-dump-connection-properties):
Remove `tramp-null-hop'.

* lisp/net/tramp-message.el (tramp-message, tramp-backtrace)
(tramp-error): Handle VEC being nil.

* lisp/net/tramp.el (tramp-null-hop): Add ;;;###tramp-autoload cookie.
Use pseudo method "local".
(tramp-file-name-unify): IF VEC is nil, set it to `tramp-null-hop'.
(tramp-set-completion-function): Support also functions with
METHOD as argument.
(tramp-get-completion-methods): Add argument HOP.
(tramp-completion-handle-file-name-all-completions): Use it.
(tramp-call-process-region): Set VEC if nil.

lisp/net/tramp-adb.el

@@ -923,7 +923,7 @@ implementation will be used."
 
 	    (when (string-match-p (rx multibyte) command)
 	      (tramp-error
-	       v 'file-error "Cannot apply multi-byte command `%s'" command))
+	       v 'file-error "Cannot apply multibyte command `%s'" command))
 
 	    (while (get-process name1)
 	      ;; NAME must be unique as process name.

lisp/net/tramp-cache.el

@@ -28,8 +28,8 @@
 ;; An implementation of information caching for remote files.
 
 ;; Each connection, identified by a `tramp-file-name' structure or by
-;; a process, has a unique cache.  We distinguish 6 kind of caches,
-;; depending on the key:
+;; a process, has a unique cache.  We distinguish several kinds of
+;; caches, depending on the key:
 ;;
 ;; - localname is nil.  These are reusable properties.  Examples:
 ;;   "remote-shell" identifies the POSIX shell to be called on the
@@ -50,11 +50,14 @@
 ;;   definitions already sent to the remote shell, "last-cmd-time" is
 ;;   the timestamp a command has been sent to the remote process.
 ;;
-;; - The key is nil.  These are temporary properties related to the
-;;   local machine.  Examples: "parse-passwd" and "parse-group" keep
-;;   the results of parsing "/etc/passwd" and "/etc/group",
+;; - The key is `tramp-null-hop' or nil.  These are temporary
+;;   properties related to the local machine.  If the key is nil, it
+;;   is silently converted into `tramp-null-hop'.
+;;   Examples: "parse-passwd" and "parse-group" keep the results of
+;;   parsing "/etc/passwd" and "/etc/group",
 ;;   "{uid,gid}-{integer,string}" are the local uid and gid, and
-;;   "locale" is the used shell locale.
+;;   "locale" is the used shell locale.  "user-host-completions" keeps
+;;   the reachable hosts for the commands in tramp-container.el.
 ;;
 ;; - The key is `tramp-cache-version'.  It keeps the Tramp version the
 ;;   cache data was produced with.  If the cache is read by another
@@ -568,6 +571,8 @@ PROPERTIES is a list of file properties (strings)."
 	       (stringp tramp-persistency-file-name))
       (let ((cache (copy-hash-table tramp-cache-data))
 	    print-length print-level)
+	;; Remove `tramp-null-hop'.
+	(remhash tramp-null-hop cache)
 	;; Remove temporary data.  If there is the key "login-as", we
 	;; don't save either, because all other properties might
 	;; depend on the login name, and we want to give the

lisp/net/tramp-message.el

@@ -328,9 +328,10 @@ applicable)."
 			       (process-buffer vec-or-proc)
 			     (tramp-get-connection-buffer
 			      vec-or-proc 'dont-create))))))))
-	    ;; Translate proc to vec.
+	    ;; Translate proc to vec.  Handle nil vec.
 	    (when (processp vec-or-proc)
-	      (setq vec-or-proc (process-get vec-or-proc 'tramp-vector))))
+	      (setq vec-or-proc (process-get vec-or-proc 'tramp-vector)))
+	    (setq vec-or-proc (tramp-file-name-unify vec-or-proc)))
 	  ;; Do it.
 	  (when (and (tramp-file-name-p vec-or-proc)
 		     (or (null tramp-debug-command-messages) (= level 6)))
@@ -351,10 +352,8 @@ forces the backtrace even if `tramp-verbose' is less than 10.
 This function is meant for debugging purposes."
   (let ((tramp-verbose (if force 10 tramp-verbose)))
     (when (>= tramp-verbose 10)
-      (if vec-or-proc
-	  (tramp-message
-	   vec-or-proc 10 "\n%s" (with-output-to-string (backtrace)))
-	(with-output-to-temp-buffer "*debug tramp*" (backtrace))))))
+      (tramp-message
+       vec-or-proc 10 "\n%s" (with-output-to-string (backtrace))))))
 
 (defsubst tramp-error (vec-or-proc signal fmt-string &rest arguments)
   "Emit an error.
@@ -370,13 +369,12 @@ FMT-STRING and ARGUMENTS."
       ;; character, as in smb domain spec.
       (setq arguments (list fmt-string)
 	    fmt-string "%s"))
-    (when vec-or-proc
-      (tramp-message
-       vec-or-proc 1 "%s"
-       (error-message-string
-	(list signal
-	      (get signal 'error-message)
-	      (apply #'format-message fmt-string arguments)))))
+    (tramp-message
+     vec-or-proc 1 "%s"
+     (error-message-string
+      (list signal
+	    (get signal 'error-message)
+	    (apply #'format-message fmt-string arguments))))
     (signal signal (list (substring-no-properties
 			  (apply #'format-message fmt-string arguments))))))
 

lisp/net/tramp.el

@@ -1190,7 +1190,7 @@ The `ftp' syntax does not support methods.")
      ;; We cannot use `tramp-prefix-regexp', because it starts with `bol'.
      (literal tramp-prefix-format)
 
-     ;; Optional multi hops.
+     ;; Optional multi-hops.
      (* (regexp tramp-remote-file-name-spec-regexp)
         (regexp tramp-postfix-hop-regexp))
 
@@ -1457,10 +1457,12 @@ calling HANDLER.")
 (function-put #'tramp-file-name-localname 'tramp-suppress-trace t)
 (function-put #'tramp-file-name-hop 'tramp-suppress-trace t)
 
-;; Needed for `tramp-read-passwd' and `tramp-get-remote-null-device'.
+;;;###tramp-autoload
 (defconst tramp-null-hop
-  (make-tramp-file-name :user (user-login-name) :host tramp-system-name)
-"Connection hop which identifies the virtual hop before the first one.")
+  (make-tramp-file-name
+   :method "local" :user (user-login-name) :host tramp-system-name)
+  "Connection hop which identifies the virtual hop before the first one.
+Used also for caching properties of the local machine.")
 
 (defun tramp-file-name-user-domain (vec)
   "Return user and domain components of VEC."
@@ -1490,14 +1492,17 @@ If nil, return `tramp-default-port'."
 ;;;###tramp-autoload
 (defun tramp-file-name-unify (vec &optional localname)
   "Unify VEC by removing localname and hop from `tramp-file-name' structure.
-If LOCALNAME is an absolute file name, set it as localname.  If
-LOCALNAME is a relative file name, return `tramp-cache-undefined'.
-Objects returned by this function compare `equal' if they refer to the
-same connection.  Make a copy in order to avoid side effects."
+IF VEC is nil, set it to `tramp-null-hop'.
+If LOCALNAME is an absolute file name, set it as localname.
+If LOCALNAME is a relative file name, return `tramp-cache-undefined'.
+Objects returned by this function compare `equal' if they refer
+to the same connection.  Make a copy in order to avoid side
+effects."
   ;; (declare (tramp-suppress-trace t))
   (if (and (stringp localname)
 	   (not (file-name-absolute-p localname)))
       (setq vec tramp-cache-undefined)
+    (unless vec (setq vec tramp-null-hop))
     (when (tramp-file-name-p vec)
       (setq vec (copy-tramp-file-name vec))
       (setf (tramp-file-name-localname vec)
@@ -2134,6 +2139,8 @@ Example:
 		    ;; DNS-SD service type.
 		    ((string-match-p
 		      tramp-dns-sd-service-regexp (nth 1 (car v))))
+		    ;; Method.
+		    ((string-equal method (nth 1 (car v))))
 		    ;; Configuration file or empty string.
 		    (t (file-exists-p (nth 1 (car v))))))
 	(setq r (delete (car v) r)))
@@ -2774,16 +2781,14 @@ not in completion mode."
 
 	    ;; Possible methods.
 	    (setq result
-		  (append result (tramp-get-completion-methods m)))))))
+		  (append result (tramp-get-completion-methods m hop)))))))
 
     ;; Unify list, add hop, remove nil elements.
     (dolist (elt result)
       (when elt
-	(string-match tramp-prefix-regexp elt)
-	(setq elt (replace-match (concat tramp-prefix-format hop) nil nil elt))
-	(push
-	 (substring elt (length (tramp-drop-volume-letter directory)))
-	 result1)))
+	(setq elt (replace-regexp-in-string
+		   tramp-prefix-regexp (concat tramp-prefix-format hop) elt))
+	(push (substring elt (length directory)) result1)))
 
     ;; Complete local parts.
     (delete-dups
@@ -2911,11 +2916,14 @@ remote host and localname (filename on remote host)."
 
 ;; This function returns all possible method completions, adding the
 ;; trailing method delimiter.
-(defun tramp-get-completion-methods (partial-method)
-  "Return all method completions for PARTIAL-METHOD."
+(defun tramp-get-completion-methods (partial-method hop)
+  "Return all method completions for PARTIAL-METHOD.
+If HOP is non-nil, return only multi-hop capable methods."
   (mapcar
    (lambda (method)
      (and method (string-prefix-p (or partial-method "") method)
+	  (or (not hop)
+	      (tramp-multi-hop-p (make-tramp-file-name :method method)))
 	  (tramp-completion-make-tramp-file-name method nil nil nil)))
    (mapcar #'car tramp-methods)))
 
@@ -6380,6 +6388,7 @@ are written with verbosity of 6."
 	(temporary-file-directory tramp-compat-temporary-file-directory)
 	(process-environment (default-toplevel-value 'process-environment))
 	(buffer (if (eq buffer t) (current-buffer) buffer))
+	(vec (or vec (car tramp-current-connection)))
 	result)
     (tramp-message
      vec 6 "`%s %s' %s %s %s %s"