CFA with optional chaining

[falsandtru]

@rbuckton

TypeScript Version: master

Search Terms:

Code

declare const o: { x: 0 } | undefined;
if (o?.x === 0) {
  o.x;
}
declare const a: [0] | undefined;
if (a?.[0] === 0) {
  a[0];
}

Expected behavior:
pass
Actual behavior:

$ node built/local/tsc --noEmit --strict index.ts
index.ts:3:3 - error TS2532: Object is possibly 'undefined'.

3   o.x;
    ~

index.ts:7:3 - error TS2532: Object is possibly 'undefined'.

7   a[0];
    ~


Found 2 errors.

Playground Link:

Related Issues:

[arciisine]

This looks to be tied to #33736.

[falsandtru]

The same idea is commented there but that issue doesn't aim it.