Avoid modifying the LSP message before resolving it (#26347)

Closes https://github.com/zed-industries/zed/issues/21277

To the left is current Zed, right is the improved version.
3rd message, from Zed, to resolve the item, does not have `textEdit` on
the right side, and has one on the left.
Seems to not influence the end result though, but at least Zed behaves
more appropriate now.

<img width="1727" alt="image"
src="https://github.com/user-attachments/assets/ca1236fd-9ce2-41ba-88fe-1f3178cdcbde"
/>


Instead of modifying the original LSP completion item, store completion
list defaults and apply them when the item is requested (except `data`
defaults, needed for resolve).

Now, the only place that can modify the completion items is this method,
and Python impl seems to be the one doing it:


ca9c3af56f/crates/languages/src/python.rs (L182-L204)

Seems ok to leave untouched for now.

Release Notes:

- Fixed LSP completion items modified before resolve request

crates/editor/src/code_context_menus.rs

@@ -500,7 +500,7 @@ impl CompletionsMenu {
                                     highlight.font_weight = None;
                                     if completion
                                         .source
-                                        .lsp_completion()
+                                        .lsp_completion(false)
                                         .and_then(|lsp_completion| lsp_completion.deprecated)
                                         .unwrap_or(false)
                                     {
@@ -711,10 +711,12 @@ impl CompletionsMenu {
 
                 let completion = &completions[mat.candidate_id];
                 let sort_key = completion.sort_key();
-                let sort_text = completion
-                    .source
-                    .lsp_completion()
-                    .and_then(|lsp_completion| lsp_completion.sort_text.as_deref());
+                let sort_text =
+                    if let CompletionSource::Lsp { lsp_completion, .. } = &completion.source {
+                        lsp_completion.sort_text.as_deref()
+                    } else {
+                        None
+                    };
                 let score = Reverse(OrderedFloat(mat.score));
 
                 if mat.score >= 0.2 {

crates/editor/src/editor.rs

@@ -17017,6 +17017,7 @@ fn snippet_completions(
                             sort_text: Some(char::MAX.to_string()),
                             ..lsp::CompletionItem::default()
                         }),
+                        lsp_defaults: None,
                     },
                     label: CodeLabel {
                         text: matching_prefix.clone(),

crates/editor/src/editor_tests.rs

@@ -12334,24 +12334,6 @@ async fn test_completions_default_resolve_data_handling(cx: &mut TestAppContext)
         },
     };
 
-    let item_0_out = lsp::CompletionItem {
-        commit_characters: Some(default_commit_characters.clone()),
-        insert_text_format: Some(default_insert_text_format),
-        ..item_0
-    };
-    let items_out = iter::once(item_0_out)
-        .chain(items[1..].iter().map(|item| lsp::CompletionItem {
-            commit_characters: Some(default_commit_characters.clone()),
-            data: Some(default_data.clone()),
-            insert_text_mode: Some(default_insert_text_mode),
-            text_edit: Some(lsp::CompletionTextEdit::Edit(lsp::TextEdit {
-                range: default_edit_range,
-                new_text: item.label.clone(),
-            })),
-            ..item.clone()
-        }))
-        .collect::<Vec<lsp::CompletionItem>>();
-
     let mut cx = EditorLspTestContext::new_rust(
         lsp::ServerCapabilities {
             completion_provider: Some(lsp::CompletionOptions {
@@ -12370,10 +12352,11 @@ async fn test_completions_default_resolve_data_handling(cx: &mut TestAppContext)
 
     let completion_data = default_data.clone();
     let completion_characters = default_commit_characters.clone();
+    let completion_items = items.clone();
     cx.handle_request::<lsp::request::Completion, _, _>(move |_, _, _| {
         let default_data = completion_data.clone();
         let default_commit_characters = completion_characters.clone();
-        let items = items.clone();
+        let items = completion_items.clone();
         async move {
             Ok(Some(lsp::CompletionResponse::List(lsp::CompletionList {
                 items,
@@ -12422,7 +12405,7 @@ async fn test_completions_default_resolve_data_handling(cx: &mut TestAppContext)
                         .iter()
                         .map(|mat| mat.string.clone())
                         .collect::<Vec<String>>(),
-                    items_out
+                    items
                         .iter()
                         .map(|completion| completion.label.clone())
                         .collect::<Vec<String>>()
@@ -12435,14 +12418,18 @@ async fn test_completions_default_resolve_data_handling(cx: &mut TestAppContext)
     // with 4 from the end.
     assert_eq!(
         *resolved_items.lock(),
-        [
-            &items_out[0..16],
-            &items_out[items_out.len() - 4..items_out.len()]
-        ]
-        .concat()
-        .iter()
-        .cloned()
-        .collect::<Vec<lsp::CompletionItem>>()
+        [&items[0..16], &items[items.len() - 4..items.len()]]
+            .concat()
+            .iter()
+            .cloned()
+            .map(|mut item| {
+                if item.data.is_none() {
+                    item.data = Some(default_data.clone());
+                }
+                item
+            })
+            .collect::<Vec<lsp::CompletionItem>>(),
+        "Items sent for resolve should be unchanged modulo resolve `data` filled with default if missing"
     );
     resolved_items.lock().clear();
 
@@ -12453,9 +12440,15 @@ async fn test_completions_default_resolve_data_handling(cx: &mut TestAppContext)
     // Completions that have already been resolved are skipped.
     assert_eq!(
         *resolved_items.lock(),
-        items_out[items_out.len() - 16..items_out.len() - 4]
+        items[items.len() - 16..items.len() - 4]
             .iter()
             .cloned()
+            .map(|mut item| {
+                if item.data.is_none() {
+                    item.data = Some(default_data.clone());
+                }
+                item
+            })
             .collect::<Vec<lsp::CompletionItem>>()
     );
     resolved_items.lock().clear();