fix: Fix old config patching overwriting callable snippet config unconditionally

Author: Veykril

crates/rust-analyzer/src/config.rs

@@ -595,6 +595,7 @@ impl Config {
                 .collect();
         patch_old_style::patch_json_for_outdated_configs(&mut json);
         self.data = ConfigData::from_json(json, &mut errors);
+        tracing::debug!("deserialized config data: {:#?}", self.data);
         self.snippets.clear();
         for (name, def) in self.data.completion_snippets_custom.iter() {
             if def.prefix.is_empty() && def.postfix.is_empty() {

crates/rust-analyzer/src/config/patch_old_style.rs

@@ -117,7 +117,8 @@ pub(super) fn patch_json_for_outdated_configs(json: &mut Value) {
     ) {
         (Some(Value::Bool(true)), Some(Value::Bool(true))) => json!("fill_arguments"),
         (Some(Value::Bool(true)), _) => json!("add_parentheses"),
-        (_, _) => json!(null),
+        (Some(Value::Bool(false)), Some(Value::Bool(false))) => json!("add_parentheses"),
+        (_, _) => return,
     };
     merge(json, json!({ "completion": { "callable": {"snippets": res }} }));
 }