Variable incorrectly inferred across await boundary

[sceutre]

TypeScript Version: 3.4.0

Search Terms: enumeration async await

Code

function wait(tm: number) {
   return new Promise((resolve, reject) => {
      setTimeout(() => resolve(true), tm);
   });
}

let x: "foo" | "bar";

async function baz() {
    x = "bar";
    await wait(1000);
    if (x == "foo") {
        // erroneous: This condition will always return 'false' since the types '"bar"' and '"foo"' have no overlap.
        console.log("could be reached");
    }
}

setTimeout(() => x = "foo", 500);
baz();

Expected behavior:

Code should compile fine

Actual behavior:

Compiler believes x must be "bar" since it was assigned such at the start of the method. However since there is an await this is not true.

Playground Link:

Playground link

Related Issues:

[MartinJohns]

Duplicate of #9998.

[sceutre]

Ah I had seen that issue but didn't read the comments in enough detail. In particular this issue is exactly what was written up in this comment: #9998 (comment)

[typescript-bot]

This issue has been marked as a 'Duplicate' and has seen no recent activity. It has been automatically closed for house-keeping purposes.