feat: handle self-param outside of methods when renaming

Author: roife

src/tools/rust-analyzer/crates/ide/src/rename.rs

@@ -421,19 +421,28 @@ fn text_edit_from_self_param(self_param: &ast::SelfParam, new_name: &str) -> Opt
         None
     }
 
-    let impl_def = self_param.syntax().ancestors().find_map(ast::Impl::cast)?;
-    let type_name = target_type_name(&impl_def)?;
-
-    let mut replacement_text = String::from(new_name);
-    replacement_text.push_str(": ");
-    match (self_param.amp_token(), self_param.mut_token()) {
-        (Some(_), None) => replacement_text.push('&'),
-        (Some(_), Some(_)) => replacement_text.push_str("&mut "),
-        (_, _) => (),
-    };
-    replacement_text.push_str(type_name.as_str());
+    match self_param.syntax().ancestors().find_map(ast::Impl::cast) {
+        Some(impl_def) => {
+            let type_name = target_type_name(&impl_def)?;
+
+            let mut replacement_text = String::from(new_name);
+            replacement_text.push_str(": ");
+            match (self_param.amp_token(), self_param.mut_token()) {
+                (Some(_), None) => replacement_text.push('&'),
+                (Some(_), Some(_)) => replacement_text.push_str("&mut "),
+                (_, _) => (),
+            };
+            replacement_text.push_str(type_name.as_str());
 
-    Some(TextEdit::replace(self_param.syntax().text_range(), replacement_text))
+            Some(TextEdit::replace(self_param.syntax().text_range(), replacement_text))
+        }
+        None => {
+            cov_mark::hit!(rename_self_outside_of_methods);
+            let mut replacement_text = String::from(new_name);
+            replacement_text.push_str(": _");
+            Some(TextEdit::replace(self_param.syntax().text_range(), replacement_text))
+        }
+    }
 }
 
 #[cfg(test)]
@@ -1977,6 +1986,26 @@ impl Foo {
         );
     }
 
+    #[test]
+    fn test_self_outside_of_methods() {
+        cov_mark::check!(rename_self_outside_of_methods);
+        check(
+            "foo",
+            r#"
+fn f($0self) -> i32 {
+    use self as _;
+    self.i
+}
+"#,
+            r#"
+fn f(foo: _) -> i32 {
+    use self as _;
+    foo.i
+}
+"#,
+        );
+    }
+
     #[test]
     fn test_self_in_path_to_parameter() {
         check(