fix(js_formatter): only parenthesize default-export function cast exp…

…ressions (#1023)

crates/biome_js_formatter/src/ts/expressions/as_expression.rs

@@ -91,6 +91,20 @@ impl NeedsParentheses for TsAsOrSatisfiesExpression {
         match parent.kind() {
             JsSyntaxKind::JS_CONDITIONAL_EXPRESSION => true,
 
+            // `export default (function foo() {} as bar)` needs to be special
+            // cased. All other default-exported as expressions can be written
+            // without parentheses, but function expressions _without_ the
+            // parentheses because `JsExportDefaultFunctionDeclaration`s and
+            // the cast becomes invalid.
+            JsSyntaxKind::JS_EXPORT_DEFAULT_EXPRESSION_CLAUSE => {
+                self.expression().map_or(false, |expression| {
+                    matches!(
+                        expression.syntax().kind(),
+                        JsSyntaxKind::JS_FUNCTION_EXPRESSION
+                    )
+                })
+            }
+
             _ => {
                 type_cast_like_needs_parens(self.syntax(), parent)
                     || is_binary_like_left_or_right(self.syntax(), parent)
@@ -152,5 +166,14 @@ mod tests {
         assert_needs_parentheses!("(x as any) instanceof (y as any)", TsAsExpression[1]);
 
         assert_not_needs_parentheses!("x as number as string", TsAsExpression[1]);
+
+        // default-exported function expressions require parentheses, otherwise
+        // the end of the function ends the export declaration, and the `as`
+        // gets treated as a new statement.
+        assert_needs_parentheses!(
+            "export default (function foo(){} as typeof console.log)",
+            TsAsExpression
+        );
+        assert_not_needs_parentheses!("export default foo as bar", TsAsExpression);
     }
 }

crates/biome_js_formatter/tests/quick_test.rs

@@ -9,31 +9,20 @@ mod language {
     include!("language.rs");
 }
 
+#[ignore]
 #[test]
 // use this test check if your snippet prints as you wish, without using a snapshot
 fn quick_test() {
     let src = r#"
-    
-const makeSomeFunction =
-(services = {logger:null}) =>
-  (a, b, c) =>
-    services.logger(a,b,c)
-
-const makeSomeFunction2 =
-(services = {
-  logger: null
-}) =>
-  (a, b, c) =>
-    services.logger(a, b, c)
-
+  export default foo as bar;
     "#;
-    let syntax = JsFileSource::tsx();
+    let source_type = JsFileSource::tsx();
     let tree = parse(
         src,
-        syntax,
+        source_type,
         JsParserOptions::default().with_parse_class_parameter_decorators(),
     );
-    let options = JsFormatOptions::new(syntax)
+    let options = JsFormatOptions::new(source_type)
         .with_indent_style(IndentStyle::Space)
         .with_semicolons(Semicolons::Always)
         .with_quote_style(QuoteStyle::Double)
@@ -42,7 +31,6 @@ const makeSomeFunction2 =
 
     let doc = format_node(options.clone(), &tree.syntax()).unwrap();
     let result = doc.print().unwrap();
-    let source_type = JsFileSource::js_module();
 
     println!("{}", doc.into_document());
     eprintln!("{}", result.as_code());