Haxe compiler Array<FunctionArg> @:optional unintuitive typing?

Test.hx

class Test {
	static function main() {
		
		var args = [{ name: "abc", type: null }]; // FAILS
		//var args = [{ name: "abc", type: null, opt: false, value: null }]; // WORKS
		//var args:Array<FunctionArg> = [{ name: "abc", type: null }]; // WORKS
		
		(args:Array<haxe.macro.Expr.FunctionArg>);
		/*
		
		Compiler throws the following error for the first option:
		
		test/Test.hx:8: characters 3-7 : Array<{ type : Null<haxe.macro.ComplexType>, name : String }> should be Array<haxe.macro.FunctionArg>
		test/Test.hx:8: characters 3-7 : Type parameters are invariant
		test/Test.hx:8: characters 3-7 : { type : Null<haxe.macro.ComplexType>, name : String } should be haxe.macro.FunctionArg
		test/Test.hx:8: characters 3-7 : { type : Null<haxe.macro.ComplexType>, name : String } should be { ?value : Null<haxe.macro.Expr>, type : Null<haxe.macro.ComplexType>, ?opt : Bool, name : String }
		test/Test.hx:8: characters 3-7 : { type : Null<haxe.macro.ComplexType>, name : String } has no field opt
		
		*/
		
	}
}