Stop releasing CIDER and cider-nrepl together

cider-nrepl now has its own release cycle and CIDER introduces
`cider-required-middleware-version` to track it.

Author: bbatsov

CHANGELOG.md

@@ -38,7 +38,7 @@
 * **(Breaking)** Move `cider-ns-refresh`, previously on `C-c C-x`, on `C-c M-n (M-)r` in the `cider-ns-map`.
 * **(Breaking)** Bump the minimum required Emacs version to 25.1.
 * **(Breaking)** Drop support for Java 7 and Clojure(Script) 1.7.
-* **(Breaking)** Use session name as part of CIDER buffers names (REPL, server, messages), and obsolete `nrepl-buffer-name-separator` and `nrepl-buffer-name-show-port`. See `cider-session-name-template` and `cider-format-connection-params` for how to customize CIDER buffer names. 
+* **(Breaking)** Use session name as part of CIDER buffers names (REPL, server, messages), and obsolete `nrepl-buffer-name-separator` and `nrepl-buffer-name-show-port`. See `cider-session-name-template` and `cider-format-connection-params` for how to customize CIDER buffer names.
 * Rename `cider-eval-defun-to-point` to `cider-eval-defun-up-to-point`.
 * Add support for printing to the current buffer to `cider-eval-defun-up-to-point`.
 * Remove `cider-ping` command.
@@ -51,6 +51,7 @@
 * **(Breaking)** Move `cider-pprint-eval-last-sexp`, previously on `C-c C-p`, to `C-c C-v (C-)f (C-)e` in the `cider-eval-commands-map`.
 * **(Breaking)** Move `cider-pprint-eval-defun-at-point`, previously on `C-c C-f`, to `C-c C-v (C-)f (C-)d` in the `cider-eval-commands-map`.
 * Accept bare figwheel-main build names (e.g., `dev`). Previously, a keyword (e.g., `:dev`) was required.
+* Stop releasing CIDER and cider-nrepl together. cider-nrepl now has its own release cycle and CIDER introduces `cider-required-middleware-version` to track it.
 
 ## 0.17.0 (2018-05-07)
 

cider-connection.el

@@ -195,17 +195,18 @@ FORMAT is a format string to compile with ARGS and display on the REPL."
                                "Can't determine Clojure's version. CIDER requires Clojure %s (or newer)."
                                cider-minimum-clojure-version)))
 
+(defvar cider-required-middleware-version)
 (defun cider--check-middleware-compatibility ()
   "CIDER frontend/backend compatibility check.
 Retrieve the underlying connection's CIDER-nREPL version and checks if the
 middleware used is compatible with CIDER.  If not, will display a warning
 message in the REPL area."
   (let* ((version-dict        (nrepl-aux-info "cider-version" (cider-current-repl)))
          (middleware-version  (nrepl-dict-get version-dict "version-string" "not installed")))
-    (unless (equal cider-version middleware-version)
+    (unless (version<= cider-required-middleware-version middleware-version)
       (cider-emit-manual-warning "troubleshooting/#cider-complains-of-the-cider-nrepl-version"
-                                 "CIDER's version (%s) does not match cider-nrepl's version (%s). Things will break!"
-                                 cider-version middleware-version))))
+                                 "CIDER %s requires cider-nrepl %s+, but you're currently using cider-nrepl %s. Things will break!"
+                                 cider-version cider-required-middleware-version middleware-version))))
 
 (declare-function cider-interactive-eval-handler "cider-eval")
 ;; TODO: Use some null handler here

cider.el

@@ -391,6 +391,12 @@ Elements of the list are artifact name and list of exclusions to apply for the a
 (defconst cider-latest-clojure-version "1.10.0"
   "Latest supported version of Clojure.")
 
+(defconst cider-required-middleware-version "0.18.0"
+  "The minimum CIDER nREPL version that's known to work properly with CIDER.")
+
+(defconst cider-latest-middleware-version "0.18.0"
+  "The latest CIDER nREPL version that's known to work properly with CIDER.")
+
 (defcustom cider-jack-in-auto-inject-clojure nil
   "Version of clojure to auto-inject into REPL.
 If nil, do not inject Clojure into the REPL.  If `latest', inject
@@ -418,7 +424,7 @@ that extend CIDER, not for users.  For example, a refactoring package might
 want to inject some middleware only when within a project context.)")
 (put 'cider-jack-in-lein-plugins 'risky-local-variable t)
 (cider-add-to-alist 'cider-jack-in-lein-plugins
-                    "cider/cider-nrepl" (upcase cider-version))
+                    "cider/cider-nrepl" cider-latest-middleware-version)
 
 (defvar cider-jack-in-cljs-lein-plugins nil
   "List of Leiningen plugins to be injected at jack-in.

doc/installation.md

@@ -202,6 +202,8 @@ It goes without saying that your project should depend on `cider-nrepl`.
 
 !!! note
 
-    `x.y.z` should match the version of CIDER you're currently using (say `0.17.0`).
-    For snapshot releases of CIDER you should use the snapshot of the plugin as well
-    (say `0.18.0-SNAPSHOT`).
+    `x.y.z` should be compatible with the version of CIDER you're currently using.
+    The required version can be checked in `cider-required-middleware-version`.
+    Prior to CIDER 0.18, CIDER and cider-nrepl were always released together
+    and their versions had to match for things to work, but as the prominence
+    of cider-nrepl grew and many other tools started using, this was changed.

doc/troubleshooting.md

@@ -143,9 +143,9 @@ effect of changes you have to restart Emacs.
 
 This is a warning displayed on the REPL buffer when it starts, and usually looks like this:
 
-> **WARNING:** CIDER's version (0.12.0) does not match cider-nrepl's version (...). Things will break!
+> **WARNING:** CIDER 0.18.0 requires cider-nrepl x.y.z+, but you're currently using cider-nrepl a.b.c. Things will break!
 
-where `...` might be an actual version, like `0.10.0`, or it might be `not installed` or `nil`.
+where `a.b.c` might be an actual version, like `0.17.0`, or it might be `not installed` or `nil`.
 The solution to this depends on what you see and on what you're doing.
 
 #### You see a number like `X.X.X`, and you're starting the REPL with `cider-connect`