Before You File a Bug Report Please Confirm You Have Done The Following...

• I have tried restarting my IDE and the issue persists.
• I have updated to the latest version of the packages.
• I havesearched for related issues and found none that matched my issue.
• I haveread the FAQ and my problem is not listed.

Playground Link

https://typescript-eslint.io/play/#ts=4.8.4&sourceType=module&code=GYVwdgxgLglg9mABMAFASgFyIG5xgEwG4AoUSWBZFADywGcoAnGMAc00QebZLOniSpqAfnpMW7LLgKIAPp3FtEAb2KJEMYIhqIAhAF59icPgCmwFqfxoVa9YkamoIRkmol1AX2LfS4fpSs6FgACoxwALYwdKYAPNL4AHy8-hRIQbQK3JKIYZHRcVwSycQAhnQAnpDIqQKIGaJZEhx5UTHxePhyTWyJtuqa2tR6hsZgZhZgVjaq9g5OLm4eiN6eQA&eslintrc=N4KABGBEBOCuA2BTAzpAXGUEKQAIBcBPABxQGNoBLY-AWhXkoDt8B6Jge1uYDcBDRgBNaPDpWFFS6KImjQO0SODABfECqA&tsconfig=N4XyA

Repro Code

functionf():void;functionf(x:string):string;functionf(x?:string):void|string{if(x!==undefined){returnx;}}functiong():Promise<void>;functiong(x:string):Promise<string>;asyncfunctiong(x?:string):Promise<void|string>{if(x!==undefined){returnx;}}

ESLint Config

module.exports={"rules":{"@typescript-eslint/no-invalid-void-type":"error"}}

tsconfig

{}

Expected Result

No errors.

Actual Result

void is only valid as a return type or generic type variable. 3:25 - 3:29
void is only valid as a return type or generic type variable. 11:39 - 11:43

Additional Info

It's possible to work around the linter in the first example by changing the implementation return type fromvoid | ... toundefined | ..., although this may require introducing an explicitreturn undefined statement to the function body if the compiler optionnoImplicitReturns is set.

In the second example, changingPromise<void | ...> toPromise<undefined | ...> is not possible because it introduces a compiler error

This overload signature is not compatible with its implementation signature. (2394)

Versions