[Fix #1297] C-c M-n should act on both repls

In a cljc or cljx buffer hitting `C-c M-n` to switch the repl ns will
now act on both repls so they are in sync.

CHANGELOG.md

@@ -46,6 +46,7 @@
 
 ### Changes
 
+* [#1397](https://github.com/clojure-emacs/cider/issues/1297) <kbd>C-c M-n</kbd> now changes the ns of both the Clojure and ClojureScript REPL (in the same project) when called from a cljc or cljx file.
 * [#1348](https://github.com/clojure-emacs/cider/issues/1348): Drop the dash dependency.
 * The usage of the default connection has been reduced significantly. Now evaluations & related commands will be routed via the connection matching the current project automatically unless there's some ambiguity when determining the connection (like multiple or no matching connections). Simply put you'll no longer have to mess around much with connecting-setting commands (e.g. `nrepl-connection-browser`, `cider-rotate-default-connection`).
 * [#732](https://github.com/clojure-emacs/cider/issues/732): `cider-quit` and `cider-restart` now operate on the current connection only. With a prefix argument they operate on all connections.

cider-client.el

@@ -202,17 +202,15 @@ such a link cannot be established automatically."
 A REPL is relevant if its `nrepl-project-dir' is compatible with the
 current directory (see `cider-find-connection-buffer-for-project-directory').
 If there is ambiguity, it is resolved by matching TYPE with the REPL
-type (Clojure or ClojureScript).  If TYPE is nil, it is derived from the
-file extension."
-  ;; Cleanup the connections list.
-  (cider-connections)
+type (Clojure or ClojureScript).  TYPE is a string, which when nil is derived
+from the file extension."
+  (cider-connections) ; Cleanup the connections list.
   (if (eq cider-request-dispatch 'dynamic)
       (cond
        ((cider--in-connection-buffer-p) (current-buffer))
        ((= 1 (length cider-connections)) (car cider-connections))
-       (t (let* ((project-directory (clojure-project-dir (cider-current-dir)))
-                 (repls (and project-directory
-                             (cider-find-connection-buffer-for-project-directory project-directory 'all))))
+       (t (let ((repls (cider-find-connection-buffer-for-project-directory
+                        nil :all-connections)))
             (if (= 1 (length repls))
                 ;; Only one match, just return it.
                 (car repls)
@@ -228,6 +226,16 @@ file extension."
     ;; TODO: Add logic to dispatch to a matching Clojure/ClojureScript REPL based on file type
     (car cider-connections)))
 
+(defun cider-other-connection (connection)
+  "Return the first connection of another type than CONNECTION, \
+in the same project, or nil."
+  (let* ((connection-type (cider--connection-type connection))
+         (other (if (equal connection-type "clj")
+                    (cider-current-connection "cljs")
+                  (cider-current-connection "clj"))))
+    (unless (equal connection-type (cider--connection-type other))
+      other)))
+
 
 ;;; Connection Browser
 (defvar cider-connections-buffer-mode-map
@@ -791,10 +799,17 @@ endpoint and Clojure version."
   "Extract the essential properties of CONN-BUFFER."
   (with-current-buffer conn-buffer
     (list
+     :type cider-repl-type
      :host (car nrepl-endpoint)
      :port (cadr nrepl-endpoint)
      :project-dir nrepl-project-dir)))
 
+(defun cider--connection-type (conn-buffer)
+  "Get CONN-BUFFER's type.
+
+Return value matches `cider-repl-type'."
+  (plist-get (cider--connection-properties conn-buffer) :type))
+
 (defun cider--connection-host (conn-buffer)
   "Get CONN-BUFFER's host."
   (plist-get (cider--connection-properties conn-buffer) :host))

cider-repl.el

@@ -35,6 +35,7 @@
 (require 'cider-eldoc) ; for cider-eldoc-setup
 (require 'cider-common)
 (require 'cider-compat)
+(require 'cider-util)
 
 (require 'clojure-mode)
 (require 'easymenu)
@@ -761,18 +762,26 @@ text property `cider-old-input'."
 (defun cider-repl-set-ns (ns)
   "Switch the namespace of the REPL buffer to NS.
 
-If invoked in a REPL buffer the command will prompt you for the name of the
+If called from a cljc or cljx buffer act on both the Clojure and
+ClojureScript REPL if there are more than one REPL present.
+
+If invoked in a REPL buffer the command will prompt for the name of the
 namespace to switch to."
   (interactive (list (if (or (derived-mode-p 'cider-repl-mode)
                              (null (cider-ns-form)))
                          (completing-read "Switch to namespace: "
                                           (cider-sync-request:ns-list))
                        (cider-current-ns))))
-  (if (and ns (not (equal ns "")))
+  (when (or (not ns) (equal ns ""))
+    (user-error "No namespace selected"))
+  (cider-nrepl-request:eval (format "(in-ns '%s)" ns)
+                            (cider-repl-switch-ns-handler
+                             (cider-current-connection)))
+  (when (cider--cljc-or-cljx-buffer-p)
+    (when-let ((other-connection (cider-other-connection
+                                  (cider-current-connection))))
       (cider-nrepl-request:eval (format "(in-ns '%s)" ns)
-                                (cider-repl-switch-ns-handler (cider-current-connection))
-                                nil)
-    (error "No namespace selected")))
+                                (cider-repl-switch-ns-handler other-connection)))))
 
 
 ;;;;; History

cider-util.el

@@ -80,6 +80,14 @@ which nREPL uses for temporary evaluation file names."
   (let ((fname (file-name-nondirectory file-name)))
     (string-match-p "^form-init" fname)))
 
+(defun cider--cljc-or-cljx-buffer-p (&optional buffer)
+  "Return true if the current buffer is visiting a cljc or cljx file.
+
+If BUFFER is provided act on that buffer instead."
+  (with-current-buffer (or buffer (current-buffer))
+    (or (derived-mode-p 'clojurec-mode) (derived-mode-p 'clojurex-mode))))
+
+
 ;;; Thing at point
 (defun cider-defun-at-point ()
   "Return the text of the top-level sexp at point."
@@ -131,6 +139,8 @@ which nREPL uses for temporary evaluation file names."
         ""
       str)))
 
+
+;;; sexp navigation
 (defun cider-sexp-at-point ()
   "Return the sexp at point as a string, otherwise nil."
   (let ((bounds (cider-bounds-of-sexp-at-point)))
@@ -171,6 +181,7 @@ Can only error if SKIP is non-nil."
       (forward-sexp 1)
       (cider-start-of-next-sexp))))
 
+
 ;;; Text properties
 
 (defun cider-maybe-intern (name)
@@ -205,6 +216,7 @@ PROP is the name of a text property."
   (when more-text (insert more-text))
   (when break (insert "\n")))
 
+
 ;;; Font lock
 
 (defun cider--font-lock-ensure ()
@@ -283,6 +295,7 @@ Unless you specify a BUFFER it will default to the current one."
       (pkg-info-version-info 'cider)
     (error cider-version)))
 
+
 ;;; Strings
 
 (defun cider-string-join (strings &optional separator)
@@ -333,6 +346,7 @@ Any other value is just returned."
       (mapcar #'cider--deep-vector-to-list x)
     x))
 
+
 ;;; Words of inspiration
 (defun cider-user-first-name ()
   "Find the current user's first name."