Expand host names in Tramp's ad-hoc multi-hop file names

* doc/misc/tramp.texi (Quick Start Guide): Improve wording.
(Change file name syntax): Say, that `tramp-file-name-regexp' is
not constant.
(Ad-hoc multi-hops): Explain host name expansion.

* etc/NEWS: Mention that host names in Tramp ad-hoc multi-hop file
names must match the previous hop for methods like "su" or "sudo".
Fix typos.

* lisp/net/tramp.el (tramp-find-method, tramp-find-user):
Adapt docstring.
(tramp-find-host): Mark default value.
(tramp-dissect-file-name): Expand host name for hops.
(tramp-dissect-hop-name, tramp-make-tramp-hop-name): New defuns.
(tramp-clear-passwd): Simplify.

* test/lisp/net/tramp-tests.el (tramp-test02-file-name-dissect)
(tramp-test02-file-name-dissect-simplified)
(tramp-test02-file-name-dissect-separate)
(tramp-test26-file-name-completion): Extend tests.

1 files changed, 108 insertions, 23 deletions

diff --git a/test/lisp/net/tramp-tests.el b/test/lisp/net/tramp-tests.el
index 6a08cbb5ab2..ceda70947c8 100644
--- a/test/lisp/net/tramp-tests.el
+++ b/test/lisp/net/tramp-tests.el
@@ -763,8 +763,8 @@ handled properly.  BODY shall not contain a timeout."
         "|-:user2@host2"
         "|-:user3@host3:/path/to/file"))
       (format "/%s:%s@%s|%s:%s@%s|%s:%s@%s:"
-              "-" "user1" "host1"
-              "-" "user2" "host2"
+              "method1" "user1" "host1"
+              "method2" "user2" "host2"
               "method3" "user3" "host3")))
 
     ;; Expand `tramp-default-user-alist'.
@@ -778,9 +778,9 @@ handled properly.  BODY shall not contain a timeout."
         "/method1:host1"
         "|method2:host2"
         "|method3:host3:/path/to/file"))
-      (format "/%s:%s|%s:%s|%s:%s@%s:"
-              "method1" "host1"
-              "method2" "host2"
+      (format "/%s:%s@%s|%s:%s@%s|%s:%s@%s:"
+              "method1" "user1" "host1"
+              "method2" "user2" "host2"
               "method3" "user3" "host3")))
 
     ;; Expand `tramp-default-host-alist'.
@@ -794,9 +794,36 @@ handled properly.  BODY shall not contain a timeout."
         "/method1:user1@"
         "|method2:user2@"
         "|method3:user3@:/path/to/file"))
-      (format "/%s:%s@|%s:%s@|%s:%s@%s:"
-              "method1" "user1"
-              "method2" "user2"
+      (format "/%s:%s@%s|%s:%s@%s|%s:%s@%s:"
+              "method1" "user1" "host1"
+              "method2" "user2" "host2"
+              "method3" "user3" "host3")))
+
+    ;; Ad-hoc user name and host name expansion.
+    (setq tramp-default-method-alist nil
+          tramp-default-user-alist nil
+          tramp-default-host-alist nil)
+    (should
+     (string-equal
+      (file-remote-p
+       (concat
+        "/method1:user1@host1"
+        "|method2:user2@"
+        "|method3:user3@:/path/to/file"))
+      (format "/%s:%s@%s|%s:%s@%s|%s:%s@%s:"
+              "method1" "user1" "host1"
+              "method2" "user2" "host1"
+              "method3" "user3" "host1")))
+    (should
+     (string-equal
+      (file-remote-p
+       (concat
+        "/method1:%u@%h"
+        "|method2:%u@%h"
+        "|method3:user3@host3:/path/to/file"))
+      (format "/%s:%s@%s|%s:%s@%s|%s:%s@%s:"
+              "method1" "user3" "host3"
+              "method2" "user3" "host3"
               "method3" "user3" "host3")))))
 
 (ert-deftest tramp-test02-file-name-dissect-simplified ()
@@ -1067,9 +1094,9 @@ handled properly.  BODY shall not contain a timeout."
               "/host1"
               "|host2"
               "|host3:/path/to/file"))
-            (format "/%s|%s|%s@%s:"
-                    "host1"
-                    "host2"
+            (format "/%s@%s|%s@%s|%s@%s:"
+                    "user1" "host1"
+                    "user2" "host2"
                     "user3" "host3")))
 
           ;; Expand `tramp-default-host-alist'.
@@ -1083,9 +1110,35 @@ handled properly.  BODY shall not contain a timeout."
               "/user1@"
               "|user2@"
               "|user3@:/path/to/file"))
-            (format "/%s@|%s@|%s@%s:"
-                    "user1"
-                    "user2"
+            (format "/%s@%s|%s@%s|%s@%s:"
+                    "user1" "host1"
+                    "user2" "host2"
+                    "user3" "host3")))
+
+          ;; Ad-hoc user name and host name expansion.
+          (setq tramp-default-user-alist nil
+                tramp-default-host-alist nil)
+          (should
+           (string-equal
+            (file-remote-p
+             (concat
+              "/user1@host1"
+              "|user2@"
+              "|user3@:/path/to/file"))
+            (format "/%s@%s|%s@%s|%s@%s:"
+                    "user1" "host1"
+                    "user2" "host1"
+                    "user3" "host1")))
+          (should
+           (string-equal
+            (file-remote-p
+             (concat
+              "/%u@%h"
+              "|%u@%h"
+              "|user3@host3:/path/to/file"))
+            (format "/%s@%s|%s@%s|%s@%s:"
+                    "user3" "host3"
+                    "user3" "host3"
                     "user3" "host3"))))
 
       ;; Exit.
@@ -1670,9 +1723,9 @@ handled properly.  BODY shall not contain a timeout."
               "/[/user1@host1"
               "|/user2@host2"
               "|/user3@host3]/path/to/file"))
-            (format "/[/%s@%s|/%s@%s|%s/%s@%s]"
-                    "user1" "host1"
-                    "user2" "host2"
+            (format "/[%s/%s@%s|%s/%s@%s|%s/%s@%s]"
+                    "method1" "user1" "host1"
+                    "method2" "user2" "host2"
                     "method3" "user3" "host3")))
 
           ;; Expand `tramp-default-user-alist'.
@@ -1686,9 +1739,9 @@ handled properly.  BODY shall not contain a timeout."
               "/[method1/host1"
               "|method2/host2"
               "|method3/host3]/path/to/file"))
-            (format "/[%s/%s|%s/%s|%s/%s@%s]"
-                    "method1" "host1"
-                    "method2" "host2"
+            (format "/[%s/%s@%s|%s/%s@%s|%s/%s@%s]"
+                    "method1" "user1" "host1"
+                    "method2" "user2" "host2"
                     "method3" "user3" "host3")))
 
           ;; Expand `tramp-default-host-alist'.
@@ -1702,9 +1755,36 @@ handled properly.  BODY shall not contain a timeout."
               "/[method1/user1@"
               "|method2/user2@"
               "|method3/user3@]/path/to/file"))
-            (format "/[%s/%s@|%s/%s@|%s/%s@%s]"
-                    "method1" "user1"
-                    "method2" "user2"
+            (format "/[%s/%s@%s|%s/%s@%s|%s/%s@%s]"
+                    "method1" "user1" "host1"
+                    "method2" "user2" "host2"
+                    "method3" "user3" "host3")))
+
+          ;; Ad-hoc user name and host name expansion.
+          (setq tramp-default-method-alist nil
+                tramp-default-user-alist nil
+                tramp-default-host-alist nil)
+          (should
+           (string-equal
+            (file-remote-p
+             (concat
+              "/[method1/user1@host1"
+              "|method2/user2@"
+              "|method3/user3@]/path/to/file"))
+            (format "/[%s/%s@%s|%s/%s@%s|%s/%s@%s]"
+                    "method1" "user1" "host1"
+                    "method2" "user2" "host1"
+                    "method3" "user3" "host1")))
+          (should
+           (string-equal
+            (file-remote-p
+             (concat
+              "/[method1/%u@%h"
+              "|method2/%u@%h"
+              "|method3/user3@host3]/path/to/file"))
+            (format "/[%s/%s@%s|%s/%s@%s|%s/%s@%s]"
+                    "method1" "user3" "host3"
+                    "method2" "user3" "host3"
                     "method3" "user3" "host3"))))
 
       ;; Exit.
@@ -3491,6 +3571,7 @@ This tests also `make-symbolic-link', `file-truename' and `add-name-to-file'."
   (when (not (memq system-type '(cygwin windows-nt)))
     (let ((method (file-remote-p tramp-test-temporary-file-directory 'method))
           (host (file-remote-p tramp-test-temporary-file-directory 'host))
+          (vec (tramp-dissect-file-name tramp-test-temporary-file-directory))
           (orig-syntax tramp-syntax))
       (when (and (stringp host) (string-match tramp-host-with-port-regexp host))
         (setq host (match-string 1 host)))
@@ -3501,6 +3582,10 @@ This tests also `make-symbolic-link', `file-truename' and `add-name-to-file'."
                (if (tramp--test-expensive-test)
                    (tramp-syntax-values) `(,orig-syntax)))
             (tramp-change-syntax syntax)
+            ;; This has cleaned up all connection data, which are used
+            ;; for completion.  We must refill the cache.
+            (tramp-set-connection-property vec "property" nil)
+
             (let ;; This is needed for the `simplified' syntax.
                 ((method-marker
                   (if (zerop (length tramp-method-regexp))