Incorrect type inference when you define slot element in v-for loop

[nkeyy0]

I'm trying to implement a table with dynamic slot names that are based on the column names, but I am faced with an issue with types in the v-for loop inside the template. For some reason the result type of the value is inferred as never, but if we do the same in the typescript we get a different type. Looks like it's an issue in the template type inferring.

Link to repro

[nkeyy0]

It looks like the issue is because of as operator. When I use the as operator in the defineSlots mapped type it isn't asserted to type I want to and remains the key, not cell-${key}. How can I handle such a case?

[so1ve]

Seemed to be a typescript limitation: https://www.typescriptlang.org/play?#code/DYUwLgBAZg9jCEAuCAKFBDZBvCA3dwAriMgHaEC2ARiAE4DcEAvgJQQC8AfHjAJYAmbAD6oM2PAWLIARIVIBrUjADupaRBHTepCAAdaMAOa0QAZ1PrN-GKRDTGrDt1x9BG0Zgg58REhCpwoOikDmxcPAIsAFBRsDAoWFEAkD5SEADk6VGsQA

[nkeyy0]

Hmm, yeah. Looks like it is. I found an issue in the TS repo related to this behavior, but looks like it can be fixed by using generics. You can find more info in this PR. And I fixed my repro according to the suggested solution in the TS PR. You can see my fix here I'm just thinking about can it be fixed directly in the Vetur, or should it be applied in the user's code?

[kermanx]

Assuming thatline 33 in the reproduction link has a missing [key]:

    <slot :name="`cell-${key}`" :value="tableRow[key]"></slot>
                                                ^^^^^

Then the problem is identical to this code.

Thus I think this is a TS limitation. We can't fix this on Vue's side.