Remove unnecessary parentheses around Luau types

src/formatters/luau.rs

@@ -474,6 +474,16 @@ pub fn format_type_info(ctx: &Context, type_info: &TypeInfo, shape: Shape) -> Ty
                     take_type_info_trailing_comments,
                     shape,
                 )
+            } else if types.len() == 1
+                && !matches!(
+                    types.iter().next().unwrap(),
+                    TypeInfo::Callback { .. }
+                        | TypeInfo::Union { .. }
+                        | TypeInfo::Intersection { .. }
+                )
+            {
+                // If its just a single type inside parentheses, and its not a function or composite type, then remove the parens
+                return singleline_types.into_iter().next().unwrap();
             } else {
                 (singleline_parentheses, singleline_types)
             };

tests/inputs-luau/excess-parentheses.lua

@@ -34,3 +34,7 @@ foo(
 	-- testing
 	(x :: string) -- testing
 )
+
+-- https://github.com/JohnnyMorganz/StyLua/issues/611
+local function foo(): (number)
+end

tests/snapshots/tests__luau@excess-parentheses.lua.snap

@@ -39,3 +39,6 @@ foo(
 	x :: string -- testing
 )
 
+-- https://github.com/JohnnyMorganz/StyLua/issues/611
+local function foo(): number end
+

tests/snapshots/tests__luau@type-callback-hang-parameters.lua.snap

@@ -6,12 +6,12 @@ export type ObservableQueryFields<TData, TVariables> = ObservableQueryPick<TData
 	fetchMore: ((
 		_self: any,
 		fetchMoreOptions: FetchMoreQueryOptions<TVariables, TData> & FetchMoreOptions<TData, TVariables>
-	) -> Promise<ApolloQueryResult<TData>>) & ((<TData2, TVariables2>(
+	) -> Promise<ApolloQueryResult<TData>>) & (<TData2, TVariables2>(
 		_self: any,
 		fetchMoreOptions: { query: (DocumentNode | TypedDocumentNode<TData, TVariables>)? }
 			& FetchMoreQueryOptions<TVariables2, TData>
 			& FetchMoreOptions<TData2, TVariables2>
-	) -> Promise<ApolloQueryResult<TData2>>)),
+	) -> Promise<ApolloQueryResult<TData2>>),
 }
 
 export type ObservableQueryFields<TData, TVariables> = ObservableQueryPick<TData, TVariables> & {

tests/snapshots/tests__luau_full_moon@named_function_arg_types.lua.snap

@@ -7,7 +7,7 @@ type MyCallbackType = (cost: number, name: string) -> string
 local cb: (amount: number) -> number
 local function foo(cb: (name: string) -> ()) end
 
-local function bar(x: (number)?): (baz: string) -> string end
+local function bar(x: number?): (baz: string) -> string end
 
-local function bar(x: (number)?): (baz: string) -> ((names: Array<string>) -> ...any) end
+local function bar(x: number?): (baz: string) -> ((names: Array<string>) -> ...any) end
 

tests/snapshots/tests__luau_full_moon@types_parentheses.lua.snap

@@ -11,7 +11,7 @@ export type Thunk<T> = (() -> T) | T
 
 export type PromiseLike<T> = {
 	andThen: (
-		((T) -> T)? | (PromiseLike<T>)?, -- resolve
+		((T) -> T)? | PromiseLike<T>?, -- resolve
 		((any) -> () | PromiseLike<T>)? -- reject
 	) -> PromiseLike<T>,
 }