Robustify in the face of manual mode changes

When manually changing the major-mode of a managed buffer, this sends
a didClose and tears down Eglot-related stuff like if were killing the
buffer.  After changing the mode, we have to recheck that we are now
not managed by another server (or by the same server, in case we
changed the mode to be the same mode).

* eglot.el (eglot-shutdown): Use eglot--with-live-buffer
(eglot--on-shutdown): Use eglot--with-live-buffer
(eglot--managed-mode): Use change-major-mode-hook.
(eglot--managed-mode-onoff): Change protocol. Turn off when called
with no arguments.
(eglot--maybe-activate-editing-mode): Don't do anything if mode is
already active.  Suitable for calling from
after-change-major-mode-hook.
(after-change-major-mode-hook): Add
eglot--maybe-activate-editing-mode.

GitHub-reference: close https://github.com/joaotavora/eglot/issues/44

diff --git a/lisp/progmodes/eglot.el b/lisp/progmodes/eglot.el
index 8f9a43d93e8c9921b2fd062008fea632934892c5..49a1f3d496b7610a5fdea31a32345f2b7434225c 100644 (file)
--- a/lisp/progmodes/eglot.el
+++ b/lisp/progmodes/eglot.el
@@ -244,7 +244,7 @@ Don't leave this function with the server still running."
         (ignore-errors (jsonrpc-request server :exit nil :timeout 1)))
     ;; Turn off `eglot--managed-mode' where appropriate.
     (dolist (buffer (eglot--managed-buffers server))
-      (with-current-buffer buffer (eglot--managed-mode-onoff server -1)))
+      (eglot--with-live-buffer buffer (eglot--managed-mode-onoff server nil)))
     ;; Now ask jsonrpc.el to shutdown server (which in normal
     ;; conditions should return immediately).
     (jsonrpc-shutdown server)))
@@ -253,7 +253,7 @@ Don't leave this function with the server still running."
   "Called by jsonrpc.el when SERVER is already dead."
   ;; Turn off `eglot--managed-mode' where appropriate.
   (dolist (buffer (eglot--managed-buffers server))
-    (with-current-buffer buffer (eglot--managed-mode-onoff server -1)))
+    (eglot--with-live-buffer buffer (eglot--managed-mode-onoff server nil)))
   ;; Kill any expensive watches
   (maphash (lambda (_id watches)
              (mapcar #'file-notify-rm-watch watches))
@@ -691,11 +691,13 @@ If optional MARKERS, make markers."
     (add-hook 'before-change-functions 'eglot--before-change nil t)
     (add-hook 'flymake-diagnostic-functions 'eglot-flymake-backend nil t)
     (add-hook 'kill-buffer-hook 'eglot--signal-textDocument/didClose nil t)
+    (add-hook 'kill-buffer-hook 'eglot--managed-mode-onoff nil t)
     (add-hook 'before-revert-hook 'eglot--signal-textDocument/didClose nil t)
     (add-hook 'before-save-hook 'eglot--signal-textDocument/willSave nil t)
     (add-hook 'after-save-hook 'eglot--signal-textDocument/didSave nil t)
     (add-hook 'xref-backend-functions 'eglot-xref-backend nil t)
     (add-hook 'completion-at-point-functions #'eglot-completion-at-point nil t)
+    (add-hook 'change-major-mode-hook 'eglot--managed-mode-onoff nil t)
     (add-function :before-until (local 'eldoc-documentation-function)
                   #'eglot-eldoc-function)
     (add-function :around (local 'imenu-create-index-function) #'eglot-imenu))
@@ -709,6 +711,7 @@ If optional MARKERS, make markers."
     (remove-hook 'after-save-hook 'eglot--signal-textDocument/didSave t)
     (remove-hook 'xref-backend-functions 'eglot-xref-backend t)
     (remove-hook 'completion-at-point-functions #'eglot-completion-at-point t)
+    (remove-hook 'change-major-mode-hook #'eglot--managed-mode-onoff t)
     (remove-function (local 'eldoc-documentation-function)
                      #'eglot-eldoc-function)
     (remove-function (local 'imenu-create-index-function) #'eglot-imenu)
@@ -718,17 +721,22 @@ If optional MARKERS, make markers."
   "A cached reference to the current EGLOT server.
 Reset in `eglot--managed-mode-onoff'.")
 
-(defun eglot--managed-mode-onoff (server arg)
-  "Proxy for function `eglot--managed-mode' with ARG and SERVER."
-  (eglot--managed-mode arg)
+(defun eglot--managed-mode-onoff (&optional server turn-on)
+  "Proxy for function `eglot--managed-mode' with TURN-ON and SERVER."
   (let ((buf (current-buffer)))
-    (cond (eglot--managed-mode
+    (cond ((and server turn-on)
+           (eglot--managed-mode 1)
            (setq eglot--cached-current-server server)
            (cl-pushnew buf (eglot--managed-buffers server)))
           (t
-           (setq eglot--cached-current-server nil)
-           (setf (eglot--managed-buffers server)
-                 (delq buf (eglot--managed-buffers server)))))))
+           (eglot--managed-mode -1)
+           (let ((server
+                  (or server
+                      eglot--cached-current-server)))
+             (setq eglot--cached-current-server nil)
+             (when server
+               (setf (eglot--managed-buffers server)
+                     (delq buf (eglot--managed-buffers server)))))))))
 
 (add-hook 'eglot--managed-mode-hook 'flymake-mode)
 (add-hook 'eglot--managed-mode-hook 'eldoc-mode)
@@ -754,21 +762,24 @@ Reset in `eglot--managed-mode-onoff'.")
   "Maybe activate mode function `eglot--managed-mode'.
 If SERVER is supplied, do it only if BUFFER is managed by it.  In
 that case, also signal textDocument/didOpen."
-  (unless server
-    (when eglot--cached-current-server
-      (display-warning
-       :eglot "`eglot--cached-current-server' is non-nil, but it should be!\n\
+  (unless eglot--managed-mode
+    (unless server
+      (when eglot--cached-current-server
+        (display-warning
+         :eglot "`eglot--cached-current-server' is non-nil, but it shouldn't be!\n\
 Please report this as a possible bug.")
-      (setq eglot--cached-current-server nil)))
-  ;; Called even when revert-buffer-in-progress-p
-  (let* ((cur (and buffer-file-name (eglot--current-server)))
-         (server (or (and (null server) cur) (and server (eq server cur) cur))))
-    (when server
-      (setq eglot--unreported-diagnostics `(:just-opened . nil))
-      (eglot--managed-mode-onoff server 1)
-      (eglot--signal-textDocument/didOpen))))
+        (setq eglot--cached-current-server nil)))
+    ;; Called even when revert-buffer-in-progress-p
+    (let* ((cur (and buffer-file-name (eglot--current-server)))
+           (server (or (and (null server) cur) (and server (eq server cur) cur))))
+      (when server
+        (setq eglot--unreported-diagnostics `(:just-opened . nil))
+        (eglot--managed-mode-onoff server t)
+        (eglot--signal-textDocument/didOpen)))))
+
 
 (add-hook 'find-file-hook 'eglot--maybe-activate-editing-mode)
+(add-hook 'after-change-major-mode-hook 'eglot--maybe-activate-editing-mode)
 
 (defun eglot-clear-status (server)
   "Clear the last JSONRPC error for SERVER."