fix(formatter): remove unnecessary parens around TSConstructorType in arrow function return type

crates/oxc_formatter/src/parentheses/ts_type.rs

@@ -45,11 +45,20 @@ impl NeedsParentheses<'_> for AstNode<'_, TSType<'_>> {
 impl NeedsParentheses<'_> for AstNode<'_, TSFunctionType<'_>> {
     #[inline]
     fn needs_parentheses(&self, _f: &Formatter<'_, '_>) -> bool {
-        function_like_type_needs_parentheses(
-            self.span(),
-            effective_parent(self.parent()),
-            Some(&self.return_type),
-        )
+        let parent = effective_parent(self.parent());
+
+        // TSFunctionType needs parens when used as an arrow function's return type
+        // to resolve syntactic ambiguity: `(): () => void => ...` is ambiguous without parens.
+        // TSConstructorType does NOT need this — the `new` keyword is unambiguous.
+        //
+        // https://github.com/prettier/prettier/blob/812a4d0071270f61a7aa549d625b618be7e09d71/src/language-js/parentheses/needs-parentheses.js#L514-L525
+        if let AstNodes::TSTypeAnnotation(type_annotation) = parent
+            && matches!(type_annotation.parent(), AstNodes::ArrowFunctionExpression(_))
+        {
+            return true;
+        }
+
+        function_like_type_needs_parentheses(self.span(), parent, Some(&self.return_type))
     }
 }
 
@@ -90,9 +99,12 @@ impl NeedsParentheses<'_> for AstNode<'_, TSUnionType<'_>> {
     }
 }
 
-/// Returns `true` if a TS primary type needs parentheses
-/// Common logic for determining if function-like types (TSFunctionType, TSConstructorType)
-/// need parentheses based on their parent context.
+/// Returns `true` if a function-like TS type (TSFunctionType, TSConstructorType)
+/// needs parentheses based on their parent context.
+///
+/// Note: The arrow-function-return-type case is handled separately by each caller,
+/// because only `TSFunctionType` needs parens there (syntactic ambiguity with `=>`),
+/// while `TSConstructorType` does not (the `new` keyword is unambiguous).
 ///
 /// Ported from Biome's function_like_type_needs_parentheses
 fn function_like_type_needs_parentheses<'a>(
@@ -101,10 +113,6 @@ fn function_like_type_needs_parentheses<'a>(
     return_type: Option<&'a TSTypeAnnotation<'a>>,
 ) -> bool {
     match parent {
-        // Arrow function return types need parens
-        AstNodes::TSTypeAnnotation(type_annotation) => {
-            matches!(type_annotation.parent(), AstNodes::ArrowFunctionExpression(_))
-        }
         // In conditional types
         AstNodes::TSConditionalType(conditional) => {
             let is_check_type = conditional.check_type().span() == span;

crates/oxc_formatter/tests/fixtures/ts/parenthesis/constructor-type-arrow-return.ts

@@ -0,0 +1,15 @@
+const f = (): (new () => Foo) => new Foo();
+
+const g = (): new () => Foo => new Foo();
+
+export const provideCloudMessagingServiceClass = (): (new () => CloudMessagingService) => {
+  return MobileCloudMessagingService;
+};
+
+const h = (): (new <T>() => T) => new Foo();
+
+const i = (): (abstract new () => Foo) => new Foo();
+
+const j = (): (() => Foo) => () => new Foo();
+
+type T = (new () => Foo) | Bar;

crates/oxc_formatter/tests/fixtures/ts/parenthesis/constructor-type-arrow-return.ts.snap

@@ -0,0 +1,62 @@
+---
+source: crates/oxc_formatter/tests/fixtures/mod.rs
+assertion_line: 229
+---
+==================== Input ====================
+const f = (): (new () => Foo) => new Foo();
+
+const g = (): new () => Foo => new Foo();
+
+export const provideCloudMessagingServiceClass = (): (new () => CloudMessagingService) => {
+  return MobileCloudMessagingService;
+};
+
+const h = (): (new <T>() => T) => new Foo();
+
+const i = (): (abstract new () => Foo) => new Foo();
+
+const j = (): (() => Foo) => () => new Foo();
+
+type T = (new () => Foo) | Bar;
+
+==================== Output ====================
+------------------
+{ printWidth: 80 }
+------------------
+const f = (): new () => Foo => new Foo();
+
+const g = (): new () => Foo => new Foo();
+
+export const provideCloudMessagingServiceClass =
+  (): new () => CloudMessagingService => {
+    return MobileCloudMessagingService;
+  };
+
+const h = (): new <T>() => T => new Foo();
+
+const i = (): abstract new () => Foo => new Foo();
+
+const j = (): (() => Foo) => () => new Foo();
+
+type T = (new () => Foo) | Bar;
+
+-------------------
+{ printWidth: 100 }
+-------------------
+const f = (): new () => Foo => new Foo();
+
+const g = (): new () => Foo => new Foo();
+
+export const provideCloudMessagingServiceClass = (): new () => CloudMessagingService => {
+  return MobileCloudMessagingService;
+};
+
+const h = (): new <T>() => T => new Foo();
+
+const i = (): abstract new () => Foo => new Foo();
+
+const j = (): (() => Foo) => () => new Foo();
+
+type T = (new () => Foo) | Bar;
+
+===================== End =====================