IDE: Properly update errors in open files upon file save

Summary:
The IDE obtains errors from two sources:
* for open files, it gets errors from its own typechecking. This allows to typecheck unsaved changes.
  * Files are rechecked upon refocusing on the tab for the file and only then
* for non-open files, it gets errors from hh_server. These appear in the problem pane. Errors from hh_server for open files are ignored

With this diff, errors from hh_server for open files do get accounted for, so long the file does not have unsaved changes. See the test plan for a better idea of how this is helpful.

Reviewed By: mheiber

Differential Revision: D71131447

fbshipit-source-id: 05e7d502127b3b519a8dde3ce18b9cda58bd52c6

Author: Catherine Gasnier

hphp/hack/src/client/clientLsp.ml

@@ -3550,7 +3550,7 @@ let handle_errors_file_item
           lenv.Run_env.uris_with_standalone_diagnostics
           |> UriMap.filter_map (fun uri (existing_time, diagnostics_from) ->
                  if
-                   UriMap.mem uri lenv.Run_env.editor_open_files
+                   UriSet.mem uri lenv.Run_env.uris_with_unsaved_changes
                    || Float.(existing_time > start_time)
                  then begin
                    Some (existing_time, diagnostics_from)
@@ -3597,7 +3597,7 @@ let handle_errors_file_item
         ~f:(fun path file_errors acc ->
           let path = Relative_path.to_absolute path in
           let uri = path_string_to_lsp_uri path ~default_path:path in
-          if UriMap.mem uri lenv.Run_env.editor_open_files then
+          if UriSet.mem uri lenv.Run_env.uris_with_unsaved_changes then
             acc
           else
             match UriMap.find_opt uri acc with

hphp/hack/test/integration/test_lsp.py

@@ -5751,17 +5751,41 @@ def test_standalone_errors(self) -> None:
                 notify=False,
             )
             .notification(
-                comment="actually open something that's different from what was on disk (with extra newline)",
+                comment="open errors_b.php",
+                method="textDocument/didOpen",
+                params={
+                    "textDocument": {
+                        "uri": "${errors_b_uri}",
+                        "languageId": "hack",
+                        "version": 1,
+                        "text": "<?hh\nfunction bbb(): int { return 2 }\n",
+                    }
+                },
+            )
+            .notification(
+                comment="open errors_a.php",
                 method="textDocument/didOpen",
                 params={
                     "textDocument": {
                         "uri": "${errors_a_uri}",
                         "languageId": "hack",
                         "version": 1,
-                        "text": "<?hh\n\n\n\nfunction aaa(): int { return 1 }\n",
+                        "text": "<?hh\nfunction aaa(): int { return 1 }\n",
                     }
                 },
             )
+            .notification(
+                comment="edit errors_a.php",
+                method="textDocument/didChange",
+                params={
+                    "textDocument": {"uri": "${errors_a_uri}", "version": 1},
+                    "contentChanges": [
+                        {
+                            "text": "<?hh\n\n\n\nfunction aaa(): int { return 1 }\n",
+                        }
+                    ],
+                },
+            )
             .wait_for_notification(
                 comment="standalone should report a squiggle in errors_a.php from serverless",
                 method="textDocument/publishDiagnostics",