Tramp: Support different proxies for the same destination

* doc/misc/tramp.texi (Ad-hoc multi-hops): New subsection "Using
different proxies for the same destination".

* etc/NEWS: Tramp supports different proxies for the same
destination host name in parallel.
Fix typos.

* lisp/net/tramp-cmds.el (tramp-cleanup-connection): Fix docstring.

* lisp/net/tramp.el (tramp-make-tramp-file-name): Don't call
`tramp-add-hops' during file name completion.
(tramp-handle-file-name-as-directory)
(tramp-handle-file-name-directory): Use `tramp-cache-undefined'
for an empty `tramp-default-proxies-alist'.
(tramp-add-hops): Extend.  Remove existing entries with same
target and different proxy, if needed.  (Bug#74219)

1 files changed, 24 insertions, 0 deletions

diff --git a/doc/misc/tramp.texi b/doc/misc/tramp.texi
index 96ec6d60b9e..a014319c02c 100644
--- a/doc/misc/tramp.texi
+++ b/doc/misc/tramp.texi
@@ -3914,6 +3914,30 @@ shall be taken, add a proper rule to the user option
 @end lisp
 
 
+@subsection Using different proxies for the same destination
+
+@strong{Note}: This feature is experimental, don't use it in
+production systems!
+
+Sometimes, it is needed to specify different proxies for the same
+destination host name.  This can happen for the same destination when
+the local host is located in different networks over the time.  This
+can also happen when the remote destination is specified by the remote
+same file name, although different hosts are meant depending on the
+used proxy.  A typical example are docker containers, which run on
+different hosts under the same docker name.
+
+When the user option @code{tramp-show-ad-hoc-proxies} is
+non-@code{nil}, such ad-hoc multi-hop file names can be used in
+parallel.  In the following, on both remote hosts @samp{host1} and
+@samp{host2} there is a docker container @samp{name}, respectively:
+
+@example
+@trampfn{ssh@value{postfixhop}user1@@host1|docker,name,}
+@trampfn{ssh@value{postfixhop}user2@@host2|docker,name,}
+@end example
+
+
 @node Home directories
 @section Expanding @file{~} to home directory