[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 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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DanielRosenwasser added 5 commits April 28, 2022 00:49

Added test case.

c95d6f7

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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.

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

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

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

This was referenced May 4, 2022

Design Meeting Notes, 4/27/2022 #48957

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

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DanielRosenwasser mentioned this pull request May 13, 2022

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

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[WIP] Contextual narrowing to object #48576

[WIP] Contextual narrowing to object #48576

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[WIP] Contextual narrowing to object #48576

[WIP] Contextual narrowing to object #48576

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