Spurious TS7024 (Function implicitly has return type 'any'...) and TS2577 (Return type annotation circularly references itself) in TS 5.1.x

[jstasiak]

Bug Report

🔎 Search Terms

• TS7024: Function implicitly has return type 'any' because it does not have a return type annotation and is referenced directly or indirectly in one of its return expressions
• TS2577: Return type annotation circularly references itself
• 5.1.6 regression

🕗 Version & Regression Information

• I see the issue with TS 5.1.3-5.1.6 and the latest nightly.
• I do not see the issue with TS 5.0.4.

• This changed between versions 5.0.4 and 5.1.3

⏯ Playground Link

Variant 1 (no return type annotations, 2x TS7024)

https://www.typescriptlang.org/play?target=99#code/GYVwdgxgLglg9mABMAPAFUQUwB5U2AEwGdEBDMATwG0BdAPgAoA3ALkQCVNSCEAbCgIIAnIaQro6ASkQBvRAF8AUMuAMqixJsTqtuxOAKZgMMJgIAaDXs0NpAXjqyFl3TRdad1xAEZ3124gOslZeWhAIRHC8mAB0vHAA5gwA5AASmLzxyZIhevJ+iG6KNDlAA

Variant 2 (I added one return type annotation, I get TS7024 + TS2577):

https://www.typescriptlang.org/play?target=99#code/GYVwdgxgLglg9mABMAPAFUQUwB5U2AEwGdEBDMATwG0BdAPgAoA3ALkQCVNSCEAbCgIIAnIaQro6ASkQBvRAF8AUMuAMqixJsTqtuxOAKZgMMJgIAaDXs0NJbJnBgFEAXjqyFl3TS9ad1xABGX2tbV3cZKwCtCAQiOF5MADpeOABzBgByAAlMXlTMySi9eRDEH0UaIqA

💻 Code

Variant 1

function f<T extends any[]>(v: ReadonlyArray<T>) { }


f([
    [
        undefined,
        () => { },
    ],
    [
        1,
        () => {
            console.log('Hello')
        },
    ],
])

Variant 2

function f<T extends any[]>(v: ReadonlyArray<T>) { }


f([
    [
        undefined,
        (): void => { },
    ],
    [
        1,
        () => {
            console.log('Hello')
        },
    ],
])

🙁 Actual behavior

The code doesn't compile.

What's strange is from my tests it seems that if I run tsc filewithcode.ts it compiles fine but if I run tsc on the whole project it produces errors.

🙂 Expected behavior

I expected the code to compile.

[MartinJohns]

What's strange is from my tests it seems that if I run tsc filewithcode.ts it compiles fine but if I run tsc on the whole project it produces errors.

Most likely you're having a tsconfig.json with noImplicitAny enabled. When running tsc on individual files the compiler won't use your project configuration, and the default value for noImplicitAny is false.

[jstasiak]

Oh yes, noImplicitAny is very much enabled (in the local project and in the playground).

[Andarist]

Bisected this to this diff. It should be safe to say that this has been changed by #53607

[ahejlsberg]

I'll take a look.

[Andarist]

For what it's worth, this circularity was introduced by this call that tries to choose between undefined and void based on the contextual return type. That leads to requesting the other signature's return type and it requests the first one again (here) because it is in its compositeSignatures.

[jstasiak]

Thank you all, I can confirm the problem is gone in the current nightly (5.2.0-dev.20230728).