Crash checking protected method accessibility: Cannot read property 'target' of undefined #47965
Description
Bug Report
I'm getting a compiler crash. It looks like it's trying to verify the accessibility of a class's protected method. I'm accessing it from a method in another class, and am accessing it via the lexical scope. I think this is related to the fact that I've explicitly defined the type of this to be T, if I remove this it doesn't crash anymore. Surprisingly, if the member is either private or public the result is correct and it no longer crashes. Please see the code sample below.
🔎 Search Terms
I searched for issues tagged as "Crash", of which none seemed to match this issue. I also looked around using variants of is:issue is:open "Cannot read property" "target" "of undefined", and I couldn't find a similar issue.
🕗 Version & Regression Information
- This is a crash visible on nightly, I tested today on
Version 4.7.0-dev.20220218.
⏯ Playground Link
As requested, here is a playground link with relevant code, but it's not very useful as the website becomes unresponsive due to the tsc crash.
💻 Code
export class Message {
protected secret(): void { }
}
export class MessageWrapper {
message: Message;
wrap<T>() {
let m = this.message;
let f = function(this: T) {
m.secret();
}
}
}🙁 Actual behavior
This input causes tsc to crash with the following error:
/c/work/tsc_crash$ npx tsc -v
Version 4.7.0-dev.20220218
/c/work/tsc_crash$ npx tsc ./message.ts
C:\work\tsc_crash\node_modules\typescript\lib\tsc.js:95457
throw e;
^
TypeError: Cannot read property 'target' of undefined
at checkPropertyAccessibilityAtLocation (C:\work\tsc_crash\node_modules\typescript\lib\tsc.js:60898:114)
at checkPropertyAccessibility (C:\work\tsc_crash\node_modules\typescript\lib\tsc.js:60839:20)
at checkPropertyAccessExpressionOrQualifiedName (C:\work\tsc_crash\node_modules\typescript\lib\tsc.js:61159:17)
at checkPropertyAccessExpression (C:\work\tsc_crash\node_modules\typescript\lib\tsc.js:60967:17)
at checkExpressionWorker (C:\work\tsc_crash\node_modules\typescript\lib\tsc.js:65661:28)
at checkExpression (C:\work\tsc_crash\node_modules\typescript\lib\tsc.js:65582:38)
at resolveCallExpression (C:\work\tsc_crash\node_modules\typescript\lib\tsc.js:62615:28)
at resolveSignature (C:\work\tsc_crash\node_modules\typescript\lib\tsc.js:62988:28)
at getResolvedSignature (C:\work\tsc_crash\node_modules\typescript\lib\tsc.js:63008:26)
at checkCallExpression (C:\work\tsc_crash\node_modules\typescript\lib\tsc.js:63117:29)
🙂 Expected behavior
Because this is a protected method, it shouldn't crash and instead return an error indicating such, ie:
message.ts:10:11 - error TS2445: Property 'secret' is protected and only accessible within class 'Message' and its subclasses.