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User-defined type guards seemingly unused when given an intersection type #10144
Description
TypeScript Version: 1.8.10
Code
interface Foo {
x: number;
s: string;
}
interface Bar {
y: number;
z: number;
}
interface HasNum {
a: number;
}
type FooOrBar = Foo | Bar;
type FooOrBarWithNum = FooOrBar & HasNum;
function is_foo(f: FooOrBar): f is Foo {
return (f as Foo).x !== undefined;
}
let obj: FooOrBarWithNum = {
a: 5,
x: 5,
s: "hello"
};
if (is_foo(obj)) {
obj.x; // ERROR: Property 'x' does not exist on type (Foo | Bar) & HasNum
}
let obj_2: FooOrBar = obj; // Cast it back to just a FooOrBar.
if (is_foo(obj_2)) {
obj_2.x; // This compiles just fine.
}Expected behavior:
I would expect obj to have type Foo inside of the if-block.
Actual behavior:
obj is not refined, but obj_2 is.
Activity
[-]User-defined type guards broken when used with Intersection Types[/-][+]User-defined type guards seemingly unused when used with Intersection Types[/+][-]User-defined type guards seemingly unused when used with Intersection Types[/-][+]User-defined type guards seemingly unused when given an intersection type[/+]yortus commentedon Aug 4, 2016
This looks related to or a duplicate of #9919
yortus commentedon Oct 21, 2016
This works now. Fixed by #11717.