Handle multiple REPL types for single project

[otwieracz]

Handle multiple REPL types for single project

Goal of this PR is to handle the issue:

1. Create and open project with lein and shadow-cljs working in one directory tree:

src
├── clj  (lein source-paths)
├── cljc (lein & shadow-cljs source-paths)
└── cljs (shadow-cljs source-paths)

2. Open .clj file, jack-in cider-jack-in-clj
3. Switch to CLJ REPL buffer with (cider-switch-to-repl-buffer) - works fine
4. Open .cljs file, jack-in cider-jack-in-cljs, accept creation of sibling REPL.
5. Switch to CLJS REPL buffer with (cider-switch-to-repl-buffer) - fails with message user-error: No clj REPLs in current session "project/project:localhost:63409"

Root cause

• There are two sesman sessions created linked to the same project:

 CIDER Sessions:

  1: project/project:localhost:63409
      linked-to: proj(~/project/)  
        objects: *cider-repl %s(clj)*  

  2: project/project:localhost:63420
      linked-to: proj(~/project/)  
        objects: *cider-repl %s(cljs:shadow)*  

• (cider-repls) uses (sesman-current-session) to get only one matching session for project (even though there might be more than one) without taking type into consideration. Then it matches type against the single result.

Proposed solution

• Look for specified type within all matching sesman sessions
• When deciding on buffer type, on cljc file detection, consult (cider-repl-type) function. This enables easy change of REPL type for CLJC buffer (which might be simultaneously used by both REPLs) with snippet like (in spacemacs):

  ;; Shortcut for easily changing REPL type in ClojureC mode
  (add-hook 'cider-mode-hook (lambda ()
                               (spacemacs/set-leader-keys-for-major-mode 'clojurec-mode "st" 'cider-set-repl-type)))

[bbatsov]

Hmm, that's weird. If I recall correctly sibling REPLs were supposed to be in the same session, otherwise they are basically unrelated.

[bbatsov]

@vspinu might be able to provide more insight here.

[vspinu]

As it happens I have started working with clojure/Cider 2 days ago after a more than a year break and immediately stumbled over this (or maybe related) issue but didn't have time to investigate.

One of the ways to reproduce my issue is to jack in twice, C-z works. Then C-c C-q on one of the processes, C-z will no longer work from the original file even though the linking is there. The reason is that cider-mode is no longer installed in those buffers. One need to revert the buffer to get C-z working again.

@otwieracz Could you check if you really have cider-mode t in the buffer that you C-z from?

Open .cljs file, jack-in cider-jack-in-cljs, accept creation of sibling REPL.

I think you are not starting the "sibling" repl, but a new repl if you press "y". That prompt is quite confusing. "Proceed Y/N?" means create a new server session altogether, not a sibling.

I cannot judge the proposed solution as I forgot the details. But the change seems unrelated to the "cider-mode disappearence" which is the culprit in my case.

[otwieracz]

@otwieracz Could you check if you really have cider-mode t in the buffer that you C-z from?

Yes, I've got cider-mode on minor-modes-list. Major mode is clojure-mode.

I think you are not starting the "sibling" repl, but a new repl if you press "y". That prompt is quite confusing. "Proceed Y/N?" means create a new server session altogether, not a sibling.

Unfortunately, there's no other way than hitting y. n is aborting the process and resulting in Quit message:

A session with the same parameters exists (project/project:localhost:51230).  You can connect a sibling instead.  Proceed? (y or n) n
Quit

[bbatsov]

See the conversation in #2946 and the updated message. Basically after pressing "n" you're expected to run cider-connect-sibling-clj(s), as nothing happens automatically. Perhaps when can reconsider this down the road and prompt the user to select what kind of sibling REPL they want.

[otwieracz]

@bbatsov unfortunately I am still getting a lot of issues with this approach:

After commenting-out my modifeid cider-repls and cider-repl-type-for-buffer and then restarting spacemacs with SPC q r:

• I've stared lein clj REPL with cider-jack-in
• Trying to start another REPL while looking at cljs file kindly greets me with this confusing message. Hitting no ends up with no action taken.
• Doing cider-connect-sibling-cljs while looking at cljs file, having already clj REPL connected from clj file from the same project results in message: : No cljs REPLs in current session "foo/bar:localhost:56670"
• Trying to start cljs sibling from clj file with above command resulted in error: error in process filter: user-error: The shadow-cljs ClojureScript REPL is not available. Please check https://docs.cider.mx/cider/basics/clojurescript for details
• After killing clj REPL, cider-jack-in-cljs from cljs starts fine but it's type is set to clj - I have to manually switch REPL type cider-set-repl-type to make sesman match this session to cljs file (before that I'm getting: user-error: No cljs REPLs in current session "foo/bar:localhost:56876")

[otwieracz]

My setup (approximate):

myproj/
   project.clj ;; for clojure
   shadow-cljs.edn ;; for clojurescript
   src/
      myproj/
         foo.clj
         bar.cljs

I expect lein and shadow-cljs to separately provide clj and cljs REPLs.

FYI, with most recent CIDER in Emacs 28 the message indeed changed but other than that problems still persist... (and my hack stopped working):

• Start CLJ repl with cider-jack-in-clj
• CLJ repl starts fine:

 CIDER Sessions:

  1: foo/myproj:localhost:53306
      linked-to: proj(~/Work/myproj/)  
        objects: *cider-repl %s(clj)*  

• Trying cider-jack-in-cljs now makes it clear what the behaviour will be:
  A CIDER session with the same connection parameters already exists (foo/myproj:localhost:53306). Are you sure you want to create a new session instead of using cider-connect-sibling-clj(s)'? (y or n) n`
• Trying cider-connect-sibling-cljs viewing cljs file in the same project:

condition-case: No cljs REPLs in current session "foo/myproj:localhost:53306"

• Starting sibling with cider-connect-sibling-cljs, selecting shadow-cljs as REPL type and :app as env:

[nREPL] Establishing direct connection to localhost:53306 ...
[nREPL] Direct connection to localhost:53306 established
error in process filter: if: The shadow-cljs ClojureScript REPL is not available.  Please check https://docs.cider.mx/cider/basics/clojurescript for details
error in process filter: The shadow-cljs ClojureScript REPL is not available.  Please check https://docs.cider.mx/cider/basics/clojurescript for details

It should start new shadow-cljs instance? Here it's trying to use existing lein connection and pretends to be surprised for not finding shadow-cljs REPL here :)

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