[#1217] Add a command for associating projects with connections

This command should mostly be used with connections created using
`cider-connect`.

CHANGELOG.md

@@ -4,6 +4,7 @@
 
 ### New features
 
+* [#1217](https://github.com/clojure-emacs/cider/issues/1217): Add new command `cider-assoc-project-with-connection` to associate a project directory with a connection.
 * [#1248](https://github.com/clojure-emacs/cider/pull/1248): Add <kbd>TAB</kbd> and <kbd>RET</kbd> keys to the test-report buffer.
 * [#1245](https://github.com/clojure-emacs/cider/pull/1245): New variable, `cider-ovelays-use-font-lock` controls whether results overlay should be font-locked or just use a single face.
 * [#1235](https://github.com/clojure-emacs/cider/pull/1235): Add support for syntax-quoted forms to the debugger.

cider-interaction.el

@@ -472,6 +472,18 @@ is ambiguity, therefore nil is returned."
       (file-name-directory buffer-file-name)
     default-directory))
 
+(defun cider-assoc-project-with-connection ()
+  "Associate a Clojure project with an nREPL connection.
+
+Useful for connections created using `cider-connect', as for them
+such a link cannot be established automatically."
+  (interactive)
+  (let ((conn-buf (completing-read "Connection: " (nrepl-connection-buffers)))
+        (project-dir (read-directory-name "Project: " nil (clojure-project-dir))))
+    (when conn-buf
+      (with-current-buffer conn-buf
+        (setq nrepl-project-dir project-dir)))))
+
 (defun cider-set-relevant-connection (&optional do-prompt)
   "Try to set the current REPL buffer based on the the current Clojure source buffer.
 If succesful, return the new connection buffer.