noUnusedLocals with allowJS and checkJS causes error

[natedanner]

TypeScript Version: 2.7.1

Search Terms:
checkJS, unusedlocals, tsc.js:59841

Code

Run: tsc test.js --noUnusedLocals --checkJS --allowJS --noEmit
With

class MyClass {

	doSomething() {
	};
}

Expected behavior:
No errors introduced

Actual behavior:
/usr/local/lib/node_modules/typescript/lib/tsc.js:59841
throw e;
^

Error: Debug Failure.
at checkUnusedClassMembers (/usr/local/lib/node_modules/typescript/lib/tsc.js:35757:38)
at checkUnusedIdentifiers (/usr/local/lib/node_modules/typescript/lib/tsc.js:35643:29)
at checkSourceFileWorker (/usr/local/lib/node_modules/typescript/lib/tsc.js:37913:21)
at checkSourceFile (/usr/local/lib/node_modules/typescript/lib/tsc.js:37891:13)
at getDiagnosticsWorker (/usr/local/lib/node_modules/typescript/lib/tsc.js:37945:17)
at Object.getDiagnostics (/usr/local/lib/node_modules/typescript/lib/tsc.js:37934:24)
at /usr/local/lib/node_modules/typescript/lib/tsc.js:59858:85
at runWithCancellationToken (/usr/local/lib/node_modules/typescript/lib/tsc.js:59834:24)
at getSemanticDiagnosticsForFileNoCache (/usr/local/lib/node_modules/typescript/lib/tsc.js:59848:20)
at getAndCacheDiagnostics (/usr/local/lib/node_modules/typescript/lib/tsc.js:60059:26)

Additional info:
If I remove the semi-colon from the doSomething method or don't pass the --noUnusedLocals flag the error does not appear. I don't get the error in either case on TypeScript version 2.6.2. We are using allowJS/checkJS feature on our legacy JS at my shop and ran into this bug after 2.7.1 upgrade

[ajafff]

Fixed by #21343?

[natedanner]

Yep! Test with latest. Closing out.

[ajafff]

@sandersn might be a good candidate for backporting

[sandersn]

Good point @ajafff. It's too late for the official 2.7 release, but it could go into 2.7.2. What do you think, @mhegazy?

[mhegazy]

It is already ported. should be released with 2.7.2

[closca]

When will release 2.7.2?

[mhegazy]

No specific ETA at the moment. but we plan it to go out sometime in the next two weeks.

[Spongman]

i think a new release containing just this bug fix would have been a good move.

[mhegazy]

2.7.2 should be live now.

[sebsto]

I have the same problem with 2.8.1

$ tsc --version
Version 2.8.1

/usr/local/lib/node_modules/typescript/lib/tsc.js:61464
                throw e;
                ^

Error: Debug Failure. False expression: Target symbol and symbol do not have the same name
    at getLiteralTypeFromPropertyName (/usr/local/lib/node_modules/typescript/lib/tsc.js:26752:30)
    at eachPropertyRelatedTo (/usr/local/lib/node_modules/typescript/lib/tsc.js:28844:36)
    at indexTypesRelatedTo (/usr/local/lib/node_modules/typescript/lib/tsc.js:28893:36)
    at structuredTypeRelatedTo (/usr/local/lib/node_modules/typescript/lib/tsc.js:28593:51)
    at recursiveTypeRelatedTo (/usr/local/lib/node_modules/typescript/lib/tsc.js:28423:53)
    at isRelatedTo (/usr/local/lib/node_modules/typescript/lib/tsc.js:28139:38)
    at checkTypeRelatedTo (/usr/local/lib/node_modules/typescript/lib/tsc.js:27990:26)
    at checkTypeComparableTo (/usr/local/lib/node_modules/typescript/lib/tsc.js:27717:20)
    at checkAssertionWorker (/usr/local/lib/node_modules/typescript/lib/tsc.js:34558:21)
    at checkAssertion (/usr/local/lib/node_modules/typescript/lib/tsc.js:34549:20)

[RyanCavanaugh]

@sebsto looks like a completely different call stack - can you open a new issue with repro steps? Thanks!

[sebsto]

I realized that after posting, new issue and steps to reproduce is here. #23461