[WIP] Contextual narrowing to object #48576

DanielRosenwasser · 2022-04-05T22:22:07Z

Related: #48468

DanielRosenwasser · 2022-04-27T19:01:28Z

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

DanielRosenwasser · 2022-04-27T23:03:03Z

Seems like there's a slowdown from this - maybe a fluke?

@typescript-bot perf test faster

typescript-bot · 2022-04-27T23:03:06Z

Heya @DanielRosenwasser, I've started to run the abridged perf test suite on this PR at 1e2eb03. You can monitor the build here.

Update: The results are in!

DanielRosenwasser · 2022-04-27T23:03:56Z

src/compiler/checker.ts

+                someType(type, isGenericTypeWithUnionConstraint) ||
+                // When the contextual type is 'unknown', we may need to narrow for compatibility with non-null targets.
+                // This allows some parity with a constraint of '{} | null | undefined'.
+                (type.flags & TypeFlags.Instantiable) && contextualType && isEmptyObjectType(contextualType);


Should this be gated on strictNullChecks?

src/compiler/checker.ts

typescript-bot · 2022-04-27T23:17:14Z

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

Here they are:

Comparison Report - main..48576

_Metric	_main	₄₈₅₇₆	_Delta	_Best	_Worst
_{Angular - node (v14.15.1, x64)}
_{Memory used}	_{333,421k (± 0.01%)}	_{333,544k (± 0.01%)}	_{+124k (+ 0.04%)}	_333,489k	_333,606k
_{Parse Time}	_{2.03s (± 0.43%)}	_{2.04s (± 0.57%)}	_{+0.01s (+ 0.54%)}	_2.02s	_2.07s
_{Bind Time}	_{0.87s (± 0.74%)}	_{0.87s (± 0.56%)}	_{+0.00s (+ 0.23%)}	_0.86s	_0.88s
_{Check Time}	_{5.63s (± 0.41%)}	_{5.73s (± 0.46%)}	_{+0.11s (+ 1.88%)}	_5.67s	_5.78s
_{Emit Time}	_{6.30s (± 0.51%)}	_{6.31s (± 0.73%)}	_{+0.01s (+ 0.14%)}	_6.21s	_6.42s
_{Total Time}	_{14.83s (± 0.33%)}	_{14.95s (± 0.47%)}	_{+0.13s (+ 0.85%)}	_14.80s	_15.09s
_{Compiler-Unions - node (v14.15.1, x64)}
_{Memory used}	_{192,431k (± 0.41%)}	_{192,049k (± 0.14%)}	_{-383k (- 0.20%)}	_191,370k	_192,339k
_{Parse Time}	_{0.85s (± 0.58%)}	_{0.85s (± 0.70%)}	_{0.00s ( 0.00%)}	_0.85s	_0.87s
_{Bind Time}	_{0.56s (± 1.57%)}	_{0.56s (± 0.40%)}	_{+0.00s (+ 0.18%)}	_0.56s	_0.57s
_{Check Time}	_{7.50s (± 0.49%)}	_{7.56s (± 0.43%)}	_{+0.06s (+ 0.76%)}	_7.50s	_7.65s
_{Emit Time}	_{2.52s (± 1.05%)}	_{2.50s (± 0.40%)}	_{-0.02s (- 0.79%)}	_2.49s	_2.53s
_{Total Time}	_{11.44s (± 0.38%)}	_{11.48s (± 0.30%)}	_{+0.04s (+ 0.31%)}	_11.41s	_11.56s
_{Monaco - node (v14.15.1, x64)}
_{Memory used}	_{325,495k (± 0.00%)}	_{325,586k (± 0.01%)}	_{+91k (+ 0.03%)}	_325,511k	_325,626k
_{Parse Time}	_{1.58s (± 0.79%)}	_{1.58s (± 0.94%)}	_{-0.00s (- 0.32%)}	_1.56s	_1.62s
_{Bind Time}	_{0.78s (± 0.47%)}	_{0.78s (± 0.64%)}	_{-0.00s (- 0.13%)}	_0.77s	_0.79s
_{Check Time}	_{5.56s (± 0.49%)}	_{5.62s (± 0.50%)}	_{+0.05s (+ 0.99%)}	_5.57s	_5.69s
_{Emit Time}	_{3.32s (± 1.07%)}	_{3.31s (± 0.72%)}	_{-0.01s (- 0.27%)}	_3.27s	_3.36s
_{Total Time}	_{11.25s (± 0.44%)}	_{11.29s (± 0.38%)}	_{+0.04s (+ 0.37%)}	_11.20s	_11.40s
_{TFS - node (v14.15.1, x64)}
_{Memory used}	_{289,058k (± 0.01%)}	_{289,197k (± 0.01%)}	_{+139k (+ 0.05%)}	_289,101k	_289,262k
_{Parse Time}	_{1.37s (± 0.65%)}	_{1.37s (± 1.67%)}	_{+0.00s (+ 0.37%)}	_1.35s	_1.43s
_{Bind Time}	_{0.73s (± 0.94%)}	_{0.72s (± 0.50%)}	_{-0.00s (- 0.28%)}	_0.72s	_0.73s
_{Check Time}	_{5.17s (± 0.25%)}	_{5.31s (± 0.41%)}	_{+0.14s (+ 2.63%)}	_5.26s	_5.35s
_{Emit Time}	_{3.52s (± 2.29%)}	_{3.50s (± 1.84%)}	_{-0.01s (- 0.40%)}	_3.40s	_3.63s
_{Total Time}	_{10.78s (± 0.72%)}	_{10.91s (± 0.69%)}	_{+0.13s (+ 1.19%)}	_10.76s	_11.08s
_{material-ui - node (v14.15.1, x64)}
_{Memory used}	_{447,685k (± 0.06%)}	_{447,773k (± 0.06%)}	_{+87k (+ 0.02%)}	_446,631k	_447,945k
_{Parse Time}	_{1.87s (± 0.56%)}	_{1.88s (± 0.64%)}	_{+0.01s (+ 0.37%)}	_1.84s	_1.90s
_{Bind Time}	_{0.70s (± 0.93%)}	_{0.70s (± 0.80%)}	_{-0.00s (- 0.00%)}	_0.69s	_0.71s
_{Check Time}	_{12.98s (± 0.67%)}	_{13.18s (± 0.64%)}	_{+0.19s (+ 1.49%)}	_13.02s	_13.47s
_{Emit Time}	_{0.00s (± 0.00%)}	_{0.00s (± 0.00%)}	_{0.00s ( NaN%)}	_0.00s	_0.00s
_{Total Time}	_{15.55s (± 0.61%)}	_{15.75s (± 0.49%)}	_{+0.21s (+ 1.32%)}	_15.59s	_16.01s
_{xstate - node (v14.15.1, x64)}
_{Memory used}	_{535,906k (± 0.00%)}	_{535,912k (± 0.00%)}	_{+7k (+ 0.00%)}	_535,876k	_535,960k
_{Parse Time}	_{2.59s (± 0.35%)}	_{2.59s (± 0.36%)}	_{+0.00s (+ 0.04%)}	_2.58s	_2.62s
_{Bind Time}	_{1.14s (± 0.70%)}	_{1.15s (± 0.66%)}	_{+0.00s (+ 0.26%)}	_1.13s	_1.16s
_{Check Time}	_{1.51s (± 0.46%)}	_{1.53s (± 0.49%)}	_{+0.02s (+ 1.06%)}	_1.51s	_1.54s
_{Emit Time}	_{0.07s (± 0.00%)}	_{0.07s (± 0.00%)}	_{0.00s ( 0.00%)}	_0.07s	_0.07s
_{Total Time}	_{5.33s (± 0.30%)}	_{5.34s (± 0.27%)}	_{+0.01s (+ 0.24%)}	_5.31s	_5.38s

System

_{Machine Name}	_ts-ci-ubuntu
_Platform	_{linux 4.4.0-210-generic}
_Architecture	_x64
_{Available Memory}	_{16 GB}
_{Available Memory}	_{2 GB}
_CPUs	_{4 × Intel(R) Core(TM) i7-4770 CPU @ 3.40GHz}

Hosts

node (v14.15.1, x64)

Scenarios

Angular - node (v14.15.1, x64)
Compiler-Unions - node (v14.15.1, x64)
Monaco - node (v14.15.1, x64)
TFS - node (v14.15.1, x64)
material-ui - node (v14.15.1, x64)
xstate - node (v14.15.1, x64)

_Benchmark	_Name	_Iterations
_Current	₄₈₅₇₆	₁₀
_Baseline	_main	₁₀

Developer Information:

Download Benchmark

…e type to empty objects.

DanielRosenwasser · 2022-04-28T01:49:42Z

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

typescript-bot · 2022-04-28T01:49:45Z

Heya @DanielRosenwasser, I've started to run the parallelized Definitely Typed test suite on this PR at ab3f21e. You can monitor the build here.

typescript-bot · 2022-04-28T01:49:45Z

Heya @DanielRosenwasser, I've started to run the extended test suite on this PR at ab3f21e. You can monitor the build here.

typescript-bot · 2022-04-28T01:49:45Z

Heya @DanielRosenwasser, I've started to run the tarball bundle task on this PR at ab3f21e. You can monitor the build here.

typescript-bot · 2022-04-28T01:49:45Z

Heya @DanielRosenwasser, I've started to run the parallelized community code test suite on this PR at ab3f21e. You can monitor the build here.

typescript-bot · 2022-04-28T02:21:22Z

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

Here they are:

Comparison Report - main..48576

_Metric	_main	₄₈₅₇₆	_Delta	_Best	_Worst
_{Angular - node (v14.15.1, x64)}
_{Memory used}	_{333,420k (± 0.01%)}	_{333,410k (± 0.01%)}	_{-10k (- 0.00%)}	_333,358k	_333,446k
_{Parse Time}	_{2.03s (± 0.77%)}	_{2.03s (± 0.47%)}	_{-0.01s (- 0.34%)}	_2.01s	_2.05s
_{Bind Time}	_{0.88s (± 0.45%)}	_{0.88s (± 0.42%)}	_{-0.00s (- 0.46%)}	_0.87s	_0.88s
_{Check Time}	_{5.63s (± 0.60%)}	_{5.60s (± 0.41%)}	_{-0.03s (- 0.59%)}	_5.56s	_5.65s
_{Emit Time}	_{6.34s (± 1.13%)}	_{6.27s (± 0.58%)}	_{-0.07s (- 1.10%)}	_6.20s	_6.34s
_{Total Time}	_{14.88s (± 0.66%)}	_{14.78s (± 0.33%)}	_{-0.11s (- 0.74%)}	_14.68s	_14.88s
_{Compiler-Unions - node (v14.15.1, x64)}
_{Memory used}	_{192,516k (± 0.37%)}	_{192,801k (± 0.51%)}	_{+285k (+ 0.15%)}	_191,559k	_195,438k
_{Parse Time}	_{0.85s (± 0.47%)}	_{0.85s (± 0.47%)}	_{0.00s ( 0.00%)}	_0.84s	_0.86s
_{Bind Time}	_{0.56s (± 0.71%)}	_{0.56s (± 0.59%)}	_{-0.00s (- 0.18%)}	_0.55s	_0.57s
_{Check Time}	_{7.51s (± 0.38%)}	_{7.48s (± 0.74%)}	_{-0.03s (- 0.33%)}	_7.40s	_7.67s
_{Emit Time}	_{2.53s (± 1.00%)}	_{2.52s (± 1.06%)}	_{-0.01s (- 0.24%)}	_2.46s	_2.59s
_{Total Time}	_{11.45s (± 0.37%)}	_{11.41s (± 0.60%)}	_{-0.03s (- 0.30%)}	_11.27s	_11.65s
_{Monaco - node (v14.15.1, x64)}
_{Memory used}	_{325,497k (± 0.01%)}	_{325,523k (± 0.00%)}	_{+27k (+ 0.01%)}	_325,496k	_325,544k
_{Parse Time}	_{1.58s (± 0.82%)}	_{1.56s (± 0.44%)}	_{-0.01s (- 0.76%)}	_1.55s	_1.58s
_{Bind Time}	_{0.78s (± 0.86%)}	_{0.78s (± 0.75%)}	_{0.00s ( 0.00%)}	_0.77s	_0.79s
_{Check Time}	_{5.56s (± 0.47%)}	_{5.54s (± 0.44%)}	_{-0.01s (- 0.23%)}	_5.50s	_5.60s
_{Emit Time}	_{3.33s (± 0.71%)}	_{3.34s (± 0.73%)}	_{+0.01s (+ 0.27%)}	_3.28s	_3.39s
_{Total Time}	_{11.24s (± 0.48%)}	_{11.22s (± 0.38%)}	_{-0.02s (- 0.13%)}	_11.12s	_11.30s
_{TFS - node (v14.15.1, x64)}
_{Memory used}	_{289,074k (± 0.01%)}	_{289,061k (± 0.01%)}	_{-14k (- 0.00%)}	_289,033k	_289,110k
_{Parse Time}	_{1.37s (± 1.84%)}	_{1.35s (± 0.66%)}	_{-0.01s (- 0.88%)}	_1.34s	_1.37s
_{Bind Time}	_{0.72s (± 0.66%)}	_{0.73s (± 1.43%)}	_{+0.01s (+ 0.69%)}	_0.72s	_0.76s
_{Check Time}	_{5.21s (± 0.33%)}	_{5.19s (± 0.44%)}	_{-0.01s (- 0.21%)}	_5.15s	_5.25s
_{Emit Time}	_{3.54s (± 2.00%)}	_{3.52s (± 2.17%)}	_{-0.02s (- 0.68%)}	_3.38s	_3.63s
_{Total Time}	_{10.84s (± 0.89%)}	_{10.79s (± 0.75%)}	_{-0.04s (- 0.39%)}	_10.63s	_10.91s
_{material-ui - node (v14.15.1, x64)}
_{Memory used}	_{447,798k (± 0.00%)}	_{447,694k (± 0.06%)}	_{-103k (- 0.02%)}	_446,660k	_447,862k
_{Parse Time}	_{1.87s (± 0.43%)}	_{1.87s (± 0.31%)}	_{-0.00s (- 0.11%)}	_1.86s	_1.88s
_{Bind Time}	_{0.70s (± 0.74%)}	_{0.70s (± 0.83%)}	_{-0.00s (- 0.57%)}	_0.69s	_0.71s
_{Check Time}	_{13.05s (± 0.82%)}	_{13.12s (± 0.79%)}	_{+0.07s (+ 0.52%)}	_12.86s	_13.32s
_{Emit Time}	_{0.00s (± 0.00%)}	_{0.00s (± 0.00%)}	_{0.00s ( NaN%)}	_0.00s	_0.00s
_{Total Time}	_{15.62s (± 0.69%)}	_{15.68s (± 0.66%)}	_{+0.06s (+ 0.38%)}	_15.44s	_15.88s
_{xstate - node (v14.15.1, x64)}
_{Memory used}	_{535,897k (± 0.00%)}	_{535,924k (± 0.00%)}	_{+27k (+ 0.01%)}	_535,903k	_535,968k
_{Parse Time}	_{2.61s (± 0.63%)}	_{2.60s (± 0.68%)}	_{-0.01s (- 0.23%)}	_2.57s	_2.66s
_{Bind Time}	_{1.15s (± 1.02%)}	_{1.14s (± 0.52%)}	_{-0.01s (- 0.61%)}	_1.13s	_1.16s
_{Check Time}	_{1.51s (± 0.49%)}	_{1.51s (± 0.72%)}	_{+0.00s (+ 0.13%)}	_1.49s	_1.54s
_{Emit Time}	_{0.07s (± 0.00%)}	_{0.07s (± 0.00%)}	_{0.00s ( 0.00%)}	_0.07s	_0.07s
_{Total Time}	_{5.34s (± 0.40%)}	_{5.33s (± 0.32%)}	_{-0.01s (- 0.15%)}	_5.31s	_5.38s

System

_{Machine Name}	_ts-ci-ubuntu
_Platform	_{linux 4.4.0-210-generic}
_Architecture	_x64
_{Available Memory}	_{16 GB}
_{Available Memory}	_{2 GB}
_CPUs	_{4 × Intel(R) Core(TM) i7-4770 CPU @ 3.40GHz}

Hosts

node (v14.15.1, x64)

Scenarios

Angular - node (v14.15.1, x64)
Compiler-Unions - node (v14.15.1, x64)
Monaco - node (v14.15.1, x64)
TFS - node (v14.15.1, x64)
material-ui - node (v14.15.1, x64)
xstate - node (v14.15.1, x64)

_Benchmark	_Name	_Iterations
_Current	₄₈₅₇₆	₁₀
_Baseline	_main	₁₀

Developer Information:

Download Benchmark

DanielRosenwasser · 2022-04-28T05:36:04Z

RWC reveals a few interesting things:

Substituting unknown for the error messages is definitely a bit confusing.
This gets worse with unions - e.g.
```
let f = <T, U extends UsefulType>(x: T | U): object => x
```
So whereas this used to report that T | U wasn't assignable to object, it now reports unknown isn't assignable to object.

Going to rerun with latest changes.

ahejlsberg · 2022-04-28T13:49:50Z

Hmm, yeah, I don't much like the error message changes in the RWC baselines. The unknown makes it seem like the expression doesn't have a type at all.

DanielRosenwasser · 2022-04-28T19:11:10Z

Discussed with @ahejlsberg offline - this PR is a bit too corner-casey and produces worse messages when a type isn't narrowed. We're interested in seeing if we can leverage smarter intersection types with {} while narrowing generics, which is a change that will have to wait for 4.8 at the least. For now we'll have to live with the break, which people can get around by adding a constraint of {} | null | undefined.

DanielRosenwasser changed the title ~~Contextual narrowing to object~~ [WIP] Contextual narrowing to object Apr 5, 2022

DanielRosenwasser mentioned this pull request Apr 5, 2022

Generic type no longer narrowed as expected without extends object #48468

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typescript-bot assigned DanielRosenwasser Apr 5, 2022

typescript-bot added Author: Team For Uncommitted Bug PR for untriaged, rejected, closed or missing bug labels Apr 5, 2022

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typescript-bot mentioned this pull request Apr 27, 2022

🤖 User test baselines have changed for contextualNarrowingToObject typescript-bot/TypeScript#234

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DanielRosenwasser requested review from weswigham and ahejlsberg April 27, 2022 23:01

DanielRosenwasser commented Apr 27, 2022

View reviewed changes

ahejlsberg reviewed Apr 27, 2022

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src/compiler/checker.ts Outdated Show resolved Hide resolved

DanielRosenwasser added 5 commits April 28, 2022 00:49

Added test case.

c95d6f7

Accepted baselines.

d4e363a

Try to change some logic for contextual narrowing for any instantiabl…

21fde45

…e type to empty objects.

Accepted baselines.

df3766d

Change in logic, up-front check for instantiables.

17b7226

DanielRosenwasser force-pushed the contextualNarrowingToObject branch from 1e2eb03 to ab3f21e Compare April 28, 2022 01:48

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Accepted baselines.

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DanielRosenwasser force-pushed the contextualNarrowingToObject branch from ab3f21e to 0ed8bff Compare April 28, 2022 05:07

DanielRosenwasser closed this Apr 28, 2022

DanielRosenwasser deleted the contextualNarrowingToObject branch April 28, 2022 20:01

This was referenced May 4, 2022

Design Meeting Notes, 4/27/2022 #48957

Closed

Investigate (possibly contextual) truthiness narrowing of type parameters #49005

Closed

DanielRosenwasser mentioned this pull request May 13, 2022

In typeof x === object, type parameters extending unknown narrow like unknown itself #49091

Closed

[WIP] Contextual narrowing to object #48576

[WIP] Contextual narrowing to object #48576

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