Repository navigation
assert.strictEqual(false, ...) triggers unreachable code error #38699
Description
assert.strictEqual(false, anyArgument) triggers unreachable code error for any code below after the recent @types/node update. This only reproduces with @types/node 10.17.24, 12.12.41, 13.13.8 (published recently).
Note that it only reproduces with false as a value being checked. Replace it with anything else and it will compile.
TypeScript Version: 3.9.3, 3.8.x as well
Search Terms: strictEqual error TS7027: Unreachable code detected
Code
import * as assert from 'assert';
const b = false;
assert.strictEqual(false, b);
console.log('really unreachable?');Expected behavior: should compile with --allowUnreachableCode false.
Actual behavior:
$ npx tsc --allowUnreachableCode false src/index.ts
src/index.ts:5:1 - error TS7027: Unreachable code detected.
5 console.log('really unreachable?');
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Found 1 error.
Playground Link: N/A because of the specific version of @types/node required for a repro.
Related Issues: N/A
Background: Here is the commit in @types/node that apparently triggers this: DefinitelyTyped/DefinitelyTyped@e910379
I reported it there as well in DefinitelyTyped/DefinitelyTyped#44944, but I have an impression the compiler behaves weirdly here.
Activity
G-Rath commentedon May 21, 2020
Cross-posting from the DT issue for coverage:
This does look like it might be a bug in tsc, as while
true&falseare given a bit of extra special treatment (iirc), it still fails if both parameters are thefalseliteral which doesn't seem right.However, you can work around it in the meantime by casting false to boolean:
ahejlsberg commentedon Jun 21, 2020
This is a bug in our code reachability analysis. It's a simple fix. Will put up a PR.
ahejlsberg commentedon Jun 21, 2020
Ah, we already have a fix in #38710, but it never got merged. Will do now.