Tramp: Do not raise an error when not connected (Bug#78572)

* lisp/net/tramp-cmds.el (tramp-cleanup-connection):
Use read syntax #' for `tramp-timeout-session',

* lisp/net/tramp.el (tramp-barf-if-file-missing): Do not raise an error
when not connected.  (Bug#78572)
(tramp-file-name-handler): Do not force the backtrace.
(tramp-connectable-p): Check also, whether initial handshake is finished.
(tramp-skeleton-directory-files)
(tramp-skeleton-directory-files-and-attributes)
(tramp-skeleton-set-file-modes-times-uid-gid): Rearrange sending
`file-missing' error.
(tramp-handle-access-file, tramp-handle-unlock-file):
Use `tramp-connectable-p'.

* test/lisp/net/tramp-tests.el (project-mode-line-format)
(project-mode-line): Declare.
(tramp-test48-session-timeout): New test.
(tramp-test49-auto-load, tramp-test49-delay-load)
(tramp-test49-recursive-load, tramp-test49-remote-load-path)
(tramp-test50-without-remote-files, tramp-test51-unload): Rename.

test/lisp/net/tramp-tests.el

@@ -67,6 +67,7 @@
 (require 'vc-git)
 (require 'vc-hg)
 
+(declare-function project-mode-line-format "project")
 (declare-function tramp-check-remote-uname "tramp-sh")
 (declare-function tramp-find-executable "tramp-sh")
 (declare-function tramp-get-remote-chmod-h "tramp-sh")
@@ -89,6 +90,7 @@
 (defvar tramp-use-connection-share)
 
 ;; Declared in Emacs 30.1.
+(defvar project-mode-line)
 (defvar remote-file-name-access-timeout)
 (defvar remote-file-name-inhibit-delete-by-moving-to-trash)
 
@@ -8374,8 +8376,52 @@ process sentinels.  They shall not disturb each other."
   ;; Cleanup.
   (tramp-cleanup-connection tramp-test-vec 'keep-debug))
 
+;; This test is inspired by Bug#78572.
+(ert-deftest tramp-test48-session-timeout ()
+  "Check that Tramp handles a session timeout properly."
+  (skip-unless (tramp--test-enabled))
+  (skip-unless
+   (tramp-get-method-parameter tramp-test-vec 'tramp-session-timeout))
+
+  ;; We want to see the timeout message.
+  (tramp--test-instrument-test-case 3
+    (let ((remote-file-name-inhibit-cache t)
+	  (tmp-name (tramp--test-make-temp-name)))
+      (unwind-protect
+	  (progn
+	    (should-not (file-exists-p tmp-name))
+	    (write-region "foo" nil tmp-name)
+	    (should (file-exists-p tmp-name))
+
+	    (tramp-timeout-session tramp-test-vec)
+	    (should (file-exists-p tmp-name))
+	    (should (directory-files (file-name-directory tmp-name)))
+
+	    ;; `project-mode-line' was introduced in Emacs 30.1.
+	    (when (boundp 'project-mode-line)
+	      (require 'project)
+	      (ert-with-message-capture captured-messages
+		(let ((project-mode-line t))
+		  (with-temp-buffer
+		    (set-visited-file-name tmp-name)
+		    (insert "foo")
+		    (should (buffer-modified-p))
+		    (tramp-timeout-session tramp-test-vec)
+		    ;; This calls `file-directory-p' and
+		    ;; `directory-files'.  Shouldn't raise an error when
+		    ;; not connected.
+		    (project-mode-line-format)
+		    ;; Steal the file lock.
+		    (cl-letf (((symbol-function #'ask-user-about-lock) #'always))
+		      (save-buffer)))
+		  (should-not
+		   (string-match-p "File is missing:" captured-messages))))))
+
+	;; Cleanup.
+	(ignore-errors (delete-file tmp-name))))))
+
 ;; This test is inspired by Bug#29163.
-(ert-deftest tramp-test48-auto-load ()
+(ert-deftest tramp-test49-auto-load ()
   "Check that Tramp autoloads properly."
   ;; If we use another syntax but `default', Tramp is already loaded
   ;; due to the `tramp-change-syntax' call.
@@ -8400,7 +8446,7 @@ process sentinels.  They shall not disturb each other."
 	(mapconcat #'shell-quote-argument load-path " -L ")
 	(shell-quote-argument code)))))))
 
-(ert-deftest tramp-test48-delay-load ()
+(ert-deftest tramp-test49-delay-load ()
   "Check that Tramp is loaded lazily, only when needed."
   ;; Tramp is neither loaded at Emacs startup, nor when completing a
   ;; non-Tramp file name like "/foo".  Completing a Tramp-alike file
@@ -8430,7 +8476,7 @@ process sentinels.  They shall not disturb each other."
 	  (mapconcat #'shell-quote-argument load-path " -L ")
 	  (shell-quote-argument (format code tm)))))))))
 
-(ert-deftest tramp-test48-recursive-load ()
+(ert-deftest tramp-test49-recursive-load ()
   "Check that Tramp does not fail due to recursive load."
   (skip-unless (tramp--test-enabled))
 
@@ -8454,7 +8500,7 @@ process sentinels.  They shall not disturb each other."
 	  (mapconcat #'shell-quote-argument load-path " -L ")
 	  (shell-quote-argument code))))))))
 
-(ert-deftest tramp-test48-remote-load-path ()
+(ert-deftest tramp-test49-remote-load-path ()
   "Check that Tramp autoloads its packages with remote `load-path'."
   ;; `tramp-cleanup-all-connections' is autoloaded from tramp-cmds.el.
   ;; It shall still work, when a remote file name is in the
@@ -8479,7 +8525,7 @@ process sentinels.  They shall not disturb each other."
 	(mapconcat #'shell-quote-argument load-path " -L ")
 	(shell-quote-argument code)))))))
 
-(ert-deftest tramp-test49-without-remote-files ()
+(ert-deftest tramp-test50-without-remote-files ()
   "Check that Tramp can be suppressed."
   (skip-unless (tramp--test-enabled))
 
@@ -8494,7 +8540,7 @@ process sentinels.  They shall not disturb each other."
   (setq tramp-mode t)
   (should (file-remote-p ert-remote-temporary-file-directory)))
 
-(ert-deftest tramp-test50-unload ()
+(ert-deftest tramp-test51-unload ()
   "Check that Tramp and its subpackages unload completely.
 Since it unloads Tramp, it shall be the last test to run."
   :tags '(:expensive-test)