Treat void-typed properties as optional #40823

rbuckton · 2020-09-29T01:25:53Z

This treats void-typed properties (or properties with a void constituent) as optional for the purpose of assignability. This is similar to how we treat trailing void parameters in signatures. The primary intended use case is to address an ECMAScript spec-compliance issue with IteratorResult, though this has possibly further-reaching consequences than just that change:

// given
interface IteratorYieldResult<TYield> {
    done?: false;
    value: TYield;
}
interface IteratorReturnResult<TReturn> {
    done: true;
    value: TReturn;
}

type IteratorResult<T, TReturn = any> = IteratorYieldResult<T> | IteratorReturnResult<TReturn>;

const myIterator: Iterator<number, void> = {
  next(value?: number) {
    return { done: true }; // `value` is not required because it is typed `void`.
  }
}

Unfortunately, simply making value optional isn't an option as it would make the result of yield* essentially always optional, as well as the result from calling .next() when iteration has completed. For example:

function * g() /*: Generator<never, number, undefined> */ {
  return 1;
}
function * f() {
  const x = yield* g(); // x should be `number`, but if `value` is optional it is `number | undefined`.
}
const result = g().next(); // IteratorResult<never, number>;
if (result.done) {
  result; // IteratorReturnResult<number>;
  result.value; // should be `number`, but if `value` is optional it is `number | undefined`.
}

I did consider changing the type of IteratorResult:

interface IteratorYieldResult<TYield> {
    done?: false;
    value: TYield;
}
interface IteratorReturnResult<TReturn> {
    done: true;
    value: TReturn;
}
interface IteratorVoidReturnResult {
  done: true;
  value?: void;
}
type IteratorResult<T, TReturn = any> =
  | IteratorYieldResult<T>
  | IteratorReturnResult<TReturn>
  | (TReturn extends void ? IteratorVoidReturnResult : never);

However that would require adding additional complexity to getIterationTypesOfIteratorResult to extract iteration types, and I'm also concerned that changing IteratorResult in this way would cause issues with assignability for existing custom iterators.

Fixes #38479

rbuckton · 2020-09-29T01:26:37Z

@typescript-bot perf test
@typescript-bot run dt
@typescript-bot test this
@typescript-bot user test this

typescript-bot · 2020-09-29T01:26:40Z

Heya @rbuckton, I've started to run the parallelized Definitely Typed test suite on this PR at be9b85d. You can monitor the build here.

typescript-bot · 2020-09-29T01:26:40Z

Heya @rbuckton, I've started to run the parallelized community code test suite on this PR at be9b85d. You can monitor the build here.

typescript-bot · 2020-09-29T01:26:40Z

Heya @rbuckton, I've started to run the extended test suite on this PR at be9b85d. You can monitor the build here.

typescript-bot · 2020-09-29T01:26:40Z

Heya @rbuckton, I've started to run the perf test suite on this PR at be9b85d. You can monitor the build here.

Update: The results are in!

typescript-bot · 2020-09-29T02:04:48Z

@rbuckton
The results of the perf run you requested are in!

Here they are:

Comparison Report - master..40823

_Metric	_master	₄₀₈₂₃	_Delta	_Best	_Worst
_{Angular - node (v10.16.3, x64)}
_{Memory used}	_{349,616k (± 0.01%)}	_{349,665k (± 0.03%)}	_{+49k (+ 0.01%)}	_349,497k	_349,945k
_{Parse Time}	_{2.00s (± 0.26%)}	_{2.01s (± 0.42%)}	_{+0.01s (+ 0.50%)}	_1.98s	_2.02s
_{Bind Time}	_{0.82s (± 0.81%)}	_{0.82s (± 0.91%)}	_{0.00s ( 0.00%)}	_0.81s	_0.85s
_{Check Time}	_{4.90s (± 0.77%)}	_{4.89s (± 0.49%)}	_{-0.01s (- 0.16%)}	_4.85s	_4.96s
_{Emit Time}	_{5.19s (± 0.52%)}	_{5.17s (± 0.51%)}	_{-0.02s (- 0.35%)}	_5.09s	_5.22s
_{Total Time}	_{12.91s (± 0.43%)}	_{12.90s (± 0.33%)}	_{-0.01s (- 0.11%)}	_12.81s	_13.00s
_{Monaco - node (v10.16.3, x64)}
_{Memory used}	_{354,341k (± 0.03%)}	_{354,311k (± 0.02%)}	_{-30k (- 0.01%)}	_354,162k	_354,413k
_{Parse Time}	_{1.56s (± 0.52%)}	_{1.56s (± 0.51%)}	_{-0.00s (- 0.13%)}	_1.54s	_1.58s
_{Bind Time}	_{0.71s (± 0.52%)}	_{0.71s (± 0.69%)}	_{-0.00s (- 0.14%)}	_0.70s	_0.72s
_{Check Time}	_{5.07s (± 0.61%)}	_{5.06s (± 0.50%)}	_{-0.01s (- 0.14%)}	_4.99s	_5.12s
_{Emit Time}	_{2.76s (± 0.86%)}	_{2.75s (± 0.59%)}	_{-0.01s (- 0.43%)}	_2.72s	_2.79s
_{Total Time}	_{10.10s (± 0.49%)}	_{10.08s (± 0.22%)}	_{-0.02s (- 0.23%)}	_10.03s	_10.13s
_{TFS - node (v10.16.3, x64)}
_{Memory used}	_{307,541k (± 0.04%)}	_{307,560k (± 0.02%)}	_{+19k (+ 0.01%)}	_307,429k	_307,667k
_{Parse Time}	_{1.21s (± 0.56%)}	_{1.21s (± 0.49%)}	_{0.00s ( 0.00%)}	_1.20s	_1.22s
_{Bind Time}	_{0.67s (± 0.99%)}	_{0.67s (± 1.21%)}	_{-0.00s (- 0.45%)}	_0.64s	_0.68s
_{Check Time}	_{4.54s (± 0.49%)}	_{4.54s (± 0.46%)}	_{-0.00s (- 0.07%)}	_4.48s	_4.58s
_{Emit Time}	_{2.90s (± 1.00%)}	_{2.92s (± 0.81%)}	_{+0.02s (+ 0.62%)}	_2.85s	_2.97s
_{Total Time}	_{9.33s (± 0.46%)}	_{9.34s (± 0.47%)}	_{+0.01s (+ 0.12%)}	_9.21s	_9.41s
_{material-ui - node (v10.16.3, x64)}
_{Memory used}	_{489,001k (± 0.01%)}	_{488,962k (± 0.01%)}	_{-39k (- 0.01%)}	_488,898k	_489,067k
_{Parse Time}	_{1.98s (± 0.45%)}	_{1.98s (± 0.69%)}	_{-0.00s (- 0.10%)}	_1.96s	_2.02s
_{Bind Time}	_{0.65s (± 0.86%)}	_{0.65s (± 0.53%)}	_{-0.00s (- 0.15%)}	_0.64s	_0.65s
_{Check Time}	_{13.50s (± 0.78%)}	_{13.59s (± 0.66%)}	_{+0.09s (+ 0.64%)}	_13.32s	_13.73s
_{Emit Time}	_{0.00s (± 0.00%)}	_{0.00s (± 0.00%)}	_{0.00s ( NaN%)}	_0.00s	_0.00s
_{Total Time}	_{16.14s (± 0.64%)}	_{16.22s (± 0.60%)}	_{+0.08s (+ 0.50%)}	_15.93s	_16.38s
_{Angular - node (v12.1.0, x64)}
_{Memory used}	_{326,839k (± 0.03%)}	_{326,684k (± 0.09%)}	_{-155k (- 0.05%)}	_325,639k	_327,041k
_{Parse Time}	_{1.99s (± 0.51%)}	_{1.99s (± 0.61%)}	_{+0.00s (+ 0.15%)}	_1.97s	_2.03s
_{Bind Time}	_{0.81s (± 0.64%)}	_{0.81s (± 0.45%)}	_{-0.00s (- 0.37%)}	_0.80s	_0.81s
_{Check Time}	_{4.80s (± 0.57%)}	_{4.79s (± 0.40%)}	_{-0.01s (- 0.19%)}	_4.75s	_4.84s
_{Emit Time}	_{5.36s (± 0.68%)}	_{5.35s (± 0.82%)}	_{-0.00s (- 0.04%)}	_5.29s	_5.51s
_{Total Time}	_{12.95s (± 0.46%)}	_{12.94s (± 0.46%)}	_{-0.01s (- 0.08%)}	_12.85s	_13.15s
_{Monaco - node (v12.1.0, x64)}
_{Memory used}	_{336,492k (± 0.01%)}	_{336,509k (± 0.03%)}	_{+18k (+ 0.01%)}	_336,355k	_336,697k
_{Parse Time}	_{1.54s (± 0.86%)}	_{1.54s (± 0.84%)}	_{-0.00s (- 0.13%)}	_1.51s	_1.57s
_{Bind Time}	_{0.70s (± 1.84%)}	_{0.69s (± 0.32%)}	_{-0.01s (- 1.29%)}	_0.69s	_0.70s
_{Check Time}	_{4.87s (± 0.47%)}	_{4.87s (± 0.51%)}	_{+0.00s (+ 0.08%)}	_4.83s	_4.92s
_{Emit Time}	_{2.83s (± 0.76%)}	_{2.81s (± 0.81%)}	_{-0.02s (- 0.67%)}	_2.77s	_2.88s
_{Total Time}	_{9.93s (± 0.47%)}	_{9.91s (± 0.38%)}	_{-0.03s (- 0.26%)}	_9.84s	_10.03s
_{TFS - node (v12.1.0, x64)}
_{Memory used}	_{291,819k (± 0.02%)}	_{291,850k (± 0.02%)}	_{+31k (+ 0.01%)}	_291,708k	_291,960k
_{Parse Time}	_{1.23s (± 0.66%)}	_{1.23s (± 0.59%)}	_{-0.00s (- 0.16%)}	_1.22s	_1.25s
_{Bind Time}	_{0.64s (± 0.90%)}	_{0.65s (± 1.15%)}	_{+0.00s (+ 0.62%)}	_0.64s	_0.67s
_{Check Time}	_{4.44s (± 0.36%)}	_{4.45s (± 0.45%)}	_{+0.01s (+ 0.16%)}	_4.40s	_4.50s
_{Emit Time}	_{2.94s (± 0.96%)}	_{2.93s (± 0.75%)}	_{-0.00s (- 0.07%)}	_2.90s	_2.98s
_{Total Time}	_{9.25s (± 0.42%)}	_{9.26s (± 0.34%)}	_{+0.01s (+ 0.12%)}	_9.18s	_9.31s
_{material-ui - node (v12.1.0, x64)}
_{Memory used}	_{466,976k (± 0.05%)}	_{466,897k (± 0.05%)}	_{-78k (- 0.02%)}	_466,019k	_467,077k
_{Parse Time}	_{2.00s (± 0.38%)}	_{2.00s (± 0.35%)}	_{-0.00s (- 0.15%)}	_1.99s	_2.02s
_{Bind Time}	_{0.64s (± 0.58%)}	_{0.64s (± 0.81%)}	_{+0.00s (+ 0.63%)}	_0.63s	_0.65s
_{Check Time}	_{12.01s (± 0.69%)}	_{12.12s (± 0.66%)}	_{+0.11s (+ 0.93%)}	_12.00s	_12.28s
_{Emit Time}	_{0.00s (± 0.00%)}	_{0.00s (± 0.00%)}	_{0.00s ( NaN%)}	_0.00s	_0.00s
_{Total Time}	_{14.65s (± 0.59%)}	_{14.76s (± 0.60%)}	_{+0.11s (+ 0.76%)}	_14.62s	_14.94s
_{Angular - node (v8.9.0, x64)}
_{Memory used}	_{346,316k (± 0.02%)}	_{346,375k (± 0.03%)}	_{+59k (+ 0.02%)}	_346,082k	_346,566k
_{Parse Time}	_{2.55s (± 0.37%)}	_{2.55s (± 0.29%)}	_{+0.01s (+ 0.20%)}	_2.54s	_2.57s
_{Bind Time}	_{0.86s (± 0.58%)}	_{0.87s (± 1.17%)}	_{+0.00s (+ 0.46%)}	_0.85s	_0.90s
_{Check Time}	_{5.54s (± 0.73%)}	_{5.55s (± 0.46%)}	_{+0.01s (+ 0.16%)}	_5.48s	_5.59s
_{Emit Time}	_{6.21s (± 1.36%)}	_{6.13s (± 1.42%)}	_{-0.09s (- 1.38%)}	_5.92s	_6.34s
_{Total Time}	_{15.17s (± 0.51%)}	_{15.09s (± 0.55%)}	_{-0.07s (- 0.47%)}	_14.86s	_15.31s
_{Monaco - node (v8.9.0, x64)}
_{Memory used}	_{355,579k (± 0.02%)}	_{355,628k (± 0.01%)}	_{+50k (+ 0.01%)}	_355,564k	_355,690k
_{Parse Time}	_{1.90s (± 0.44%)}	_{1.89s (± 0.47%)}	_{-0.01s (- 0.47%)}	_1.87s	_1.91s
_{Bind Time}	_{0.89s (± 0.82%)}	_{0.90s (± 0.67%)}	_{+0.00s (+ 0.34%)}	_0.88s	_0.91s
_{Check Time}	_{5.62s (± 0.55%)}	_{5.60s (± 0.57%)}	_{-0.01s (- 0.25%)}	_5.50s	_5.67s
_{Emit Time}	_{3.31s (± 1.50%)}	_{3.31s (± 1.15%)}	_{+0.00s (+ 0.12%)}	_3.19s	_3.36s
_{Total Time}	_{11.71s (± 0.55%)}	_{11.70s (± 0.58%)}	_{-0.01s (- 0.12%)}	_11.50s	_11.80s
_{TFS - node (v8.9.0, x64)}
_{Memory used}	_{309,276k (± 0.01%)}	_{309,310k (± 0.01%)}	_{+34k (+ 0.01%)}	_309,218k	_309,401k
_{Parse Time}	_{1.56s (± 0.32%)}	_{1.55s (± 0.54%)}	_{-0.01s (- 0.45%)}	_1.54s	_1.58s
_{Bind Time}	_{0.68s (± 0.95%)}	_{0.68s (± 0.86%)}	_{-0.00s (- 0.15%)}	_0.66s	_0.69s
_{Check Time}	_{5.30s (± 0.59%)}	_{5.29s (± 0.37%)}	_{-0.00s (- 0.08%)}	_5.25s	_5.33s
_{Emit Time}	_{2.93s (± 0.80%)}	_{2.93s (± 0.48%)}	_{-0.00s (- 0.14%)}	_2.90s	_2.95s
_{Total Time}	_{10.46s (± 0.28%)}	_{10.45s (± 0.21%)}	_{-0.02s (- 0.14%)}	_10.38s	_10.48s
_{material-ui - node (v8.9.0, x64)}
_{Memory used}	_{493,347k (± 0.02%)}	_{493,314k (± 0.01%)}	_{-33k (- 0.01%)}	_493,128k	_493,459k
_{Parse Time}	_{2.40s (± 0.36%)}	_{2.40s (± 0.44%)}	_{+0.00s (+ 0.04%)}	_2.38s	_2.43s
_{Bind Time}	_{0.81s (± 1.17%)}	_{0.82s (± 0.71%)}	_{+0.00s (+ 0.37%)}	_0.80s	_0.83s
_{Check Time}	_{17.92s (± 0.84%)}	_{18.09s (± 0.92%)}	_{+0.17s (+ 0.97%)}	_17.67s	_18.42s
_{Emit Time}	_{0.00s (± 0.00%)}	_{0.00s (± 0.00%)}	_{0.00s ( NaN%)}	_0.00s	_0.00s
_{Total Time}	_{21.14s (± 0.68%)}	_{21.32s (± 0.77%)}	_{+0.18s (+ 0.85%)}	_20.89s	_21.65s
_{Angular - node (v8.9.0, x86)}
_{Memory used}	_{198,593k (± 0.02%)}	_{198,625k (± 0.02%)}	_{+32k (+ 0.02%)}	_198,529k	_198,736k
_{Parse Time}	_{2.48s (± 0.81%)}	_{2.47s (± 0.43%)}	_{-0.01s (- 0.44%)}	_2.44s	_2.49s
_{Bind Time}	_{1.00s (± 0.93%)}	_{1.00s (± 1.15%)}	_{+0.00s (+ 0.50%)}	_0.97s	_1.03s
_{Check Time}	_{4.99s (± 0.61%)}	_{5.00s (± 0.43%)}	_{+0.01s (+ 0.14%)}	_4.95s	_5.05s
_{Emit Time}	_{5.92s (± 0.90%)}	_{5.93s (± 1.24%)}	_{+0.01s (+ 0.17%)}	_5.80s	_6.14s
_{Total Time}	_{14.39s (± 0.56%)}	_{14.40s (± 0.47%)}	_{+0.01s (+ 0.08%)}	_14.23s	_14.57s
_{Monaco - node (v8.9.0, x86)}
_{Memory used}	_{201,394k (± 0.01%)}	_{201,381k (± 0.02%)}	_{-13k (- 0.01%)}	_201,277k	_201,437k
_{Parse Time}	_{1.93s (± 0.81%)}	_{1.93s (± 0.69%)}	_{-0.00s (- 0.21%)}	_1.90s	_1.96s
_{Bind Time}	_{0.71s (± 0.91%)}	_{0.71s (± 0.78%)}	_{0.00s ( 0.00%)}	_0.70s	_0.72s
_{Check Time}	_{5.46s (± 1.24%)}	_{5.50s (± 1.37%)}	_{+0.04s (+ 0.79%)}	_5.38s	_5.68s
_{Emit Time}	_{3.03s (± 3.23%)}	_{2.97s (± 3.51%)}	_{-0.06s (- 1.91%)}	_2.65s	_3.08s
_{Total Time}	_{11.13s (± 0.64%)}	_{11.10s (± 0.71%)}	_{-0.02s (- 0.22%)}	_10.92s	_11.30s
_{TFS - node (v8.9.0, x86)}
_{Memory used}	_{176,811k (± 0.02%)}	_{176,806k (± 0.03%)}	_{-5k (- 0.00%)}	_176,732k	_176,961k
_{Parse Time}	_{1.58s (± 0.84%)}	_{1.58s (± 0.53%)}	_{-0.00s (- 0.13%)}	_1.57s	_1.60s
_{Bind Time}	_{0.65s (± 1.23%)}	_{0.64s (± 0.90%)}	_{-0.01s (- 0.77%)}	_0.63s	_0.66s
_{Check Time}	_{4.79s (± 0.56%)}	_{4.78s (± 0.65%)}	_{-0.00s (- 0.10%)}	_4.73s	_4.85s
_{Emit Time}	_{2.80s (± 1.10%)}	_{2.79s (± 1.14%)}	_{-0.01s (- 0.36%)}	_2.73s	_2.90s
_{Total Time}	_{9.82s (± 0.40%)}	_{9.80s (± 0.47%)}	_{-0.02s (- 0.17%)}	_9.71s	_9.88s
_{material-ui - node (v8.9.0, x86)}
_{Memory used}	_{277,775k (± 0.01%)}	_{277,740k (± 0.02%)}	_{-35k (- 0.01%)}	_277,637k	_277,879k
_{Parse Time}	_{2.46s (± 0.82%)}	_{2.46s (± 0.54%)}	_{-0.00s (- 0.04%)}	_2.43s	_2.50s
_{Bind Time}	_{0.71s (± 5.86%)}	_{0.74s (± 7.55%)}	_{+0.02s (+ 3.51%)}	_0.67s	_0.87s
_{Check Time}	_{16.38s (± 0.69%)}	_{16.55s (± 0.74%)}	_{+0.17s (+ 1.01%)}	_16.37s	_16.92s
_{Emit Time}	_{0.00s (± 0.00%)}	_{0.00s (± 0.00%)}	_{0.00s ( NaN%)}	_0.00s	_0.00s
_{Total Time}	_{19.55s (± 0.74%)}	_{19.74s (± 0.69%)}	_{+0.19s (+ 0.96%)}	_19.48s	_20.07s

System

_{Machine Name}	_ts-ci-ubuntu
_Platform	_{linux 4.4.0-166-generic}
_Architecture	_x64
_{Available Memory}	_{16 GB}
_{Available Memory}	_{1 GB}
_CPUs	_{4 × Intel(R) Core(TM) i7-4770 CPU @ 3.40GHz}

Hosts

node (v10.16.3, x64)
node (v12.1.0, x64)
node (v8.9.0, x64)
node (v8.9.0, x86)

Scenarios

Angular - node (v10.16.3, x64)
Angular - node (v12.1.0, x64)
Angular - node (v8.9.0, x64)
Angular - node (v8.9.0, x86)
Monaco - node (v10.16.3, x64)
Monaco - node (v12.1.0, x64)
Monaco - node (v8.9.0, x64)
Monaco - node (v8.9.0, x86)
TFS - node (v10.16.3, x64)
TFS - node (v12.1.0, x64)
TFS - node (v8.9.0, x64)
TFS - node (v8.9.0, x86)
material-ui - node (v10.16.3, x64)
material-ui - node (v12.1.0, x64)
material-ui - node (v8.9.0, x64)
material-ui - node (v8.9.0, x86)

_Benchmark	_Name	_Iterations
_Current	₄₀₈₂₃	₁₀
_Baseline	_master	₁₀

typescript-bot · 2020-09-29T02:16:53Z

The user suite test run you requested has finished and failed. I've opened a PR with the baseline diff from master.

sandersn · 2020-10-09T21:30:37Z

@rbuckton where did we land on this? I remember discussing something like this in the design meeting, but not whether we decided to go forward with it.

sandersn · 2021-03-11T00:11:23Z

@rbuckton do you mind if I close this until we come up with a comprehensive reform of void? At least, my memory of our last discussion of this is that we're kind of stuck on this particular change. I might be mis-remembering, though.

sandersn · 2022-03-10T19:04:39Z

Closing this for now.

rbuckton requested review from DanielRosenwasser, weswigham and ahejlsberg September 29, 2020 01:25

typescript-bot assigned rbuckton Sep 29, 2020

typescript-bot added Author: Team For Milestone Bug PRs that fix a bug with a specific milestone labels Sep 29, 2020

rbuckton mentioned this pull request Sep 29, 2020

Add IteratorVoidReturnResult for optional 'value' when done #40825

Closed

typescript-bot mentioned this pull request Sep 29, 2020

🤖 User test baselines have changed for optionalVoidProperties typescript-bot/TypeScript#87

Open

rbuckton force-pushed the optionalVoidProperties branch from be9b85d to 7e73fef Compare September 29, 2020 03:14

Treat void-typed properties as optional

d261d4d

rbuckton force-pushed the optionalVoidProperties branch from 7e73fef to d261d4d Compare September 29, 2020 20:45

brainkim mentioned this pull request Feb 9, 2021

#AvoidTheVoid Allow users to avoid the void type. #42709

Open

5 tasks

weswigham removed their request for review March 4, 2022 19:21

sandersn closed this Mar 10, 2022

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Treat void-typed properties as optional #40823

Treat void-typed properties as optional #40823

rbuckton commented Sep 29, 2020

rbuckton commented Sep 29, 2020

typescript-bot commented Sep 29, 2020 •

edited

Loading

typescript-bot commented Sep 29, 2020 •

edited

Loading

typescript-bot commented Sep 29, 2020 •

edited

Loading

typescript-bot commented Sep 29, 2020 •

edited

Loading

typescript-bot commented Sep 29, 2020

typescript-bot commented Sep 29, 2020

sandersn commented Oct 9, 2020

sandersn commented Mar 11, 2021

sandersn commented Mar 10, 2022

Treat void-typed properties as optional #40823

Treat void-typed properties as optional #40823

Conversation

rbuckton commented Sep 29, 2020

rbuckton commented Sep 29, 2020

typescript-bot commented Sep 29, 2020 • edited Loading

typescript-bot commented Sep 29, 2020 • edited Loading

typescript-bot commented Sep 29, 2020 • edited Loading

typescript-bot commented Sep 29, 2020 • edited Loading

typescript-bot commented Sep 29, 2020

typescript-bot commented Sep 29, 2020

sandersn commented Oct 9, 2020

sandersn commented Mar 11, 2021

sandersn commented Mar 10, 2022

typescript-bot commented Sep 29, 2020 •

edited

Loading

typescript-bot commented Sep 29, 2020 •

edited

Loading

typescript-bot commented Sep 29, 2020 •

edited

Loading

typescript-bot commented Sep 29, 2020 •

edited

Loading