Enhancement: no-floating-promises shouldn't allow returning a variable containing an unawaited promise. Returning an unawaited promise directly is fine. #8068
Description
Before You File a Proposal Please Confirm You Have Done The Following...
- I have searched for related issues and found none that match my proposal.
- I have searched the current rule list and found no rules that match my proposal.
- I have read the FAQ and my problem is not listed.
My proposal is suitable for this project
- I believe my proposal would be useful to the broader TypeScript community (meaning it is not a niche proposal).
Link to the rule's documentation
https://typescript-eslint.io/rules/no-floating-promises/
Description
no-floating-promise considers returning an unawaited promise is always ok.
While this is fine when you return the promise directly (ie return f()), this can be an issue if there are some intermediary steps before returning. I just spent a few hours trying to fix such a bug !
For example consider the following pseudocode :
async createObject(id:string){ ..... }
async x(id:string){
const a = createObject(id); // note the missing await
await doSomethingWithObject(id); // will fail because the object doesn't exist yet
return a; // return the unawaited Promise, eslint doesn't complain
}if doSomethingWithObject logically depends on the promise being on the previous line being resolved, this is a bug and should be flagged as such by eslint!
if doSomethingWithObject doesn't depend on the previous line being resolved, then we can rearrange the code:
async x(){
await doSomethingWithObject(); //doesn't depend on anything, so can be moved to the first line
return createObject(); // here, the missing await is ok as we are returning immediately
// the caller will be responsible for handling the promise properly
}Fail
async f(){ ..... }
async x(){
const a = f();
g();
return a; // mishandled promise. Cannot return a variable containing an unawaited promise.
// await it, or return it directly ( ie. return f() )
}Pass
async f(){ ..... }
async x(){
g();
return f(); // g doesn't need to be executed after f, move g() before f() and return f() directly
or
async f(){ ..... }
async x(){
const a = await f(); // g is supposed to be executed after f, add the missing await
g();
return a;
}Additional Info
No response