eglot should flush recent changes before didSave notification

[mkcms]

When I make a change in the buffer, and then immediately save it, didChange events are ran after didSave notifications. This leads to eglot and some servers having different document versions. This happens to me with eclipse.jdt.ls LSP server. Other servers that I tested simply ignore TextDocument/didSave notifications so it will never happen. Here is an example with eclipse.jdt.ls:

package com.frog.test;

public class App
{
    public static void main(String[] args)
    {
	int a;
    }
}

1. Go to 7th line.
2. M-x kill-whole-line
3. Quickly do C-x C-s (before recent changes are sent)

client-notification Sat Aug  4 11:36:16 2018:
(:jsonrpc "2.0" :method "textDocument/didSave" :params
	  (:text "package com.frog.test;\n\npublic class App\n{\n    public static void main(String[] args)\n    {\n    }\n}\n" :textDocument
		 (:uri "file:///home/michal/src/eclipse-workspace/test/src/main/java/com/frog/test/App.java")))

server-notification Sat Aug  4 11:36:16 2018:
(:jsonrpc "2.0" :method "window/logMessage" :params
	  (:type 3 :message "Aug 4, 2018 11:36:16 AM >> document/didSave"))

client-notification Sat Aug  4 11:36:17 2018:
(:jsonrpc "2.0" :method "textDocument/didChange" :params
	  (:textDocument
	   (:uri "file:///home/michal/src/eclipse-workspace/test/src/main/java/com/frog/test/App.java" :version 2)
	   :contentChanges
	   [(:range
	     (:start
	      (:line 6 :character 0)
	      :end
	      (:line 6 :character 7))
	     :rangeLength 7 :text "")
	    (:range
	     (:start
	      (:line 6 :character 0)
	      :end
	      (:line 7 :character 0))
	     :rangeLength 1 :text "")]))

One solution to it is to ensure recent changes are flushed before every notification.

[mkcms]

Despite the fact that the program is correct, this leads to diagnostics such as:

server-notification Sat Aug  4 11:36:18 2018:
(:jsonrpc "2.0" :method "textDocument/publishDiagnostics" :params
	  (:uri "file:///home/michal/src/eclipse-workspace/test/src/main/java/com/frog/test/App.java" :diagnostics
		[(:range
		  (:start
		   (:line 3 :character 0)
		   :end
		   (:line 3 :character 1))
		  :severity 1 :code "1610612976" :source "Java" :message "Syntax error, insert \"}\" to complete ClassBody")
		 (:range
		  (:start
		   (:line 5 :character 4)
		   :end
		   (:line 5 :character 5))
		  :severity 1 :code "1610612976" :source "Java" :message "Syntax error, insert \"}\" to complete MethodBody")]))

[joaotavora]

This happens to me with eclipse.jdt.ls LSP server.

By the way, when you can, make a PR to add this to the README.md and eglot-server-programs.

One solution to it is to ensure recent changes are flushed before every notification.

Don't you mean before each didSave notification?

diff --git a/eglot.el b/eglot.el
index c3a0d51..afe6911 100644
--- a/eglot.el
+++ b/eglot.el
@@ -1116,6 +1116,7 @@ When called interactively, use the currently active server"
 
 (defun eglot--signal-textDocument/didSave ()
   "Send textDocument/didSave to server."
+  (eglot--signal-textDocument/didChange)
   (jsonrpc-notify
    (eglot--current-server-or-lose)
    :textDocument/didSave

[mkcms]

By the way, when you can, make a PR to add this to the README.md and eglot-server-programs.

I'll try, although this server has a lot of configurable parameters. I think at least two defcustoms are needed for it.

Don't you mean before each didSave notification?

I meant before every notification just to be safe but perhaps that's too much. I'm not sure if other notifications depend on didChange notifications.