doc: Note about diagnostic mapping.

helix-view/src/document.rs

@@ -213,10 +213,14 @@ impl Document {
                     .unwrap();
             }
 
-            // if let Some(diagnostics) = &mut self.diagnostics {
+            // map state.diagnostics over changes::map_pos too
-            //     for diagnostic in diagnostics {
+            // NOTE: seems to do nothing since the language server resends diagnostics on each edit
-            //         // TODO: map state.diagnostics over changes::map_pos too
+            // for diagnostic in &mut self.diagnostics {
-            //     }
+            //     use helix_core::Assoc;
+            //     let changes = transaction.changes();
+            //     diagnostic.range.start = changes.map_pos(diagnostic.range.start, Assoc::After);
+            //     diagnostic.range.end = changes.map_pos(diagnostic.range.end, Assoc::After);
+            //     diagnostic.line = self.text.char_to_line(diagnostic.range.start);
             // }
 
             // emit lsp notification