Properly handle null and undefined in getCommonSupertype #50021

ahejlsberg · 2022-07-23T19:59:09Z

This is an alternative fix for #49938 that supercedes #49981.

@jakebailey I found it easier to put up a new PR. I've copied the tests from #49981. This PR more uniformly lifts undefined and null from the inference candidates and then adds them back later, plus it's a bit better at avoiding duplicate work. For example, it handles this case that otherwise is an error:

let v = null!;

declare function foo<T>(x: T, y: T): T;

const x = foo(v as 'a' | undefined, v as 'b');

ahejlsberg · 2022-07-23T20:00:38Z

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

ahejlsberg · 2022-07-23T21:30:14Z

@typescript-bot test this

typescript-bot · 2022-07-23T21:30:17Z

Heya @ahejlsberg, I've started to run the extended test suite on this PR at d4a239c. You can monitor the build here.

ahejlsberg · 2022-07-23T21:31:06Z

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

typescript-bot · 2022-07-23T21:31:09Z

Heya @ahejlsberg, I've started to run the diff-based user code test suite on this PR at d4a239c. You can monitor the build here.

Update: The results are in!

typescript-bot · 2022-07-23T21:31:09Z

Heya @ahejlsberg, I've started to run the abridged perf test suite on this PR at d4a239c. You can monitor the build here.

Update: The results are in!

typescript-bot · 2022-07-23T21:31:09Z

Heya @ahejlsberg, I've started to run the parallelized Definitely Typed test suite on this PR at d4a239c. You can monitor the build here.

ahejlsberg · 2022-07-23T21:31:26Z

@typescript-bot pack this

typescript-bot · 2022-07-23T21:31:28Z

Heya @ahejlsberg, I've started to run the tarball bundle task on this PR at d4a239c. You can monitor the build here.

typescript-bot · 2022-07-23T21:45:36Z

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

Here they are:

Comparison Report - main..50021

_Metric	_main	₅₀₀₂₁	_Delta	_Best	_Worst
_{Angular - node (v14.15.1, x64)}
_{Memory used}	_{335,938k (± 0.01%)}	_{335,962k (± 0.01%)}	_{+24k (+ 0.01%)}	_335,871k	_336,005k
_{Parse Time}	_{2.06s (± 0.65%)}	_{2.06s (± 0.46%)}	_{-0.01s (- 0.39%)}	_2.04s	_2.08s
_{Bind Time}	_{0.90s (± 1.30%)}	_{0.90s (± 0.72%)}	_{-0.00s (- 0.11%)}	_0.89s	_0.91s
_{Check Time}	_{5.82s (± 0.41%)}	_{5.83s (± 0.41%)}	_{+0.01s (+ 0.19%)}	_5.77s	_5.89s
_{Emit Time}	_{6.38s (± 0.63%)}	_{6.38s (± 0.63%)}	_{-0.01s (- 0.08%)}	_6.27s	_6.43s
_{Total Time}	_{15.17s (± 0.37%)}	_{15.16s (± 0.43%)}	_{-0.01s (- 0.05%)}	_14.98s	_15.24s
_{Compiler-Unions - node (v14.15.1, x64)}
_{Memory used}	_{193,129k (± 0.01%)}	_{193,453k (± 0.38%)}	_{+324k (+ 0.17%)}	_193,001k	_196,437k
_{Parse Time}	_{0.85s (± 0.68%)}	_{0.84s (± 0.43%)}	_{-0.00s (- 0.35%)}	_0.84s	_0.85s
_{Bind Time}	_{0.57s (± 1.01%)}	_{0.57s (± 1.13%)}	_{+0.00s (+ 0.35%)}	_0.56s	_0.59s
_{Check Time}	_{6.71s (± 0.80%)}	_{6.73s (± 0.58%)}	_{+0.03s (+ 0.39%)}	_6.64s	_6.83s
_{Emit Time}	_{2.49s (± 0.87%)}	_{2.49s (± 0.82%)}	_{+0.01s (+ 0.28%)}	_2.46s	_2.55s
_{Total Time}	_{10.61s (± 0.54%)}	_{10.64s (± 0.38%)}	_{+0.03s (+ 0.29%)}	_10.54s	_10.74s
_{Monaco - node (v14.15.1, x64)}
_{Memory used}	_{325,664k (± 0.01%)}	_{325,647k (± 0.01%)}	_{-17k (- 0.01%)}	_325,601k	_325,702k
_{Parse Time}	_{1.58s (± 0.48%)}	_{1.59s (± 0.70%)}	_{+0.01s (+ 0.63%)}	_1.56s	_1.61s
_{Bind Time}	_{0.78s (± 0.71%)}	_{0.79s (± 1.06%)}	_{+0.00s (+ 0.38%)}	_0.77s	_0.81s
_{Check Time}	_{5.71s (± 0.46%)}	_{5.67s (± 0.36%)}	_{-0.03s (- 0.56%)}	_5.64s	_5.73s
_{Emit Time}	_{3.36s (± 0.58%)}	_{3.34s (± 0.75%)}	_{-0.02s (- 0.60%)}	_3.28s	_3.40s
_{Total Time}	_{11.42s (± 0.36%)}	_{11.38s (± 0.34%)}	_{-0.04s (- 0.32%)}	_11.34s	_11.51s
_{TFS - node (v14.15.1, x64)}
_{Memory used}	_{288,822k (± 0.01%)}	_{288,845k (± 0.01%)}	_{+23k (+ 0.01%)}	_288,795k	_288,931k
_{Parse Time}	_{1.33s (± 1.04%)}	_{1.33s (± 1.76%)}	_{+0.00s (+ 0.23%)}	_1.29s	_1.39s
_{Bind Time}	_{0.77s (± 4.36%)}	_{0.77s (± 4.05%)}	_{-0.00s (- 0.00%)}	_0.73s	_0.85s
_{Check Time}	_{5.36s (± 0.26%)}	_{5.33s (± 0.50%)}	_{-0.03s (- 0.54%)}	_5.27s	_5.39s
_{Emit Time}	_{3.54s (± 1.81%)}	_{3.62s (± 1.92%)}	_{+0.08s (+ 2.18%)}	_3.46s	_3.73s
_{Total Time}	_{10.99s (± 0.57%)}	_{11.04s (± 0.73%)}	_{+0.05s (+ 0.48%)}	_10.82s	_11.17s
_{material-ui - node (v14.15.1, x64)}
_{Memory used}	_{446,711k (± 0.01%)}	_{446,730k (± 0.01%)}	_{+19k (+ 0.00%)}	_446,661k	_446,786k
_{Parse Time}	_{1.88s (± 0.62%)}	_{1.88s (± 0.64%)}	_{-0.00s (- 0.05%)}	_1.85s	_1.91s
_{Bind Time}	_{0.72s (± 1.23%)}	_{0.72s (± 0.97%)}	_{-0.01s (- 0.83%)}	_0.71s	_0.74s
_{Check Time}	_{13.18s (± 0.51%)}	_{13.24s (± 0.58%)}	_{+0.07s (+ 0.51%)}	_13.11s	_13.44s
_{Emit Time}	_{0.00s (± 0.00%)}	_{0.00s (± 0.00%)}	_{0.00s ( NaN%)}	_0.00s	_0.00s
_{Total Time}	_{15.78s (± 0.47%)}	_{15.85s (± 0.52%)}	_{+0.06s (+ 0.39%)}	_15.70s	_16.04s
_{xstate - node (v14.15.1, x64)}
_{Memory used}	_{541,295k (± 0.01%)}	_{541,308k (± 0.00%)}	_{+13k (+ 0.00%)}	_541,260k	_541,341k
_{Parse Time}	_{2.60s (± 0.29%)}	_{2.61s (± 0.32%)}	_{+0.01s (+ 0.35%)}	_2.58s	_2.62s
_{Bind Time}	_{1.15s (± 1.24%)}	_{1.14s (± 1.57%)}	_{-0.01s (- 0.61%)}	_1.10s	_1.20s
_{Check Time}	_{1.56s (± 0.49%)}	_{1.56s (± 0.72%)}	_{-0.00s (- 0.06%)}	_1.53s	_1.58s
_{Emit Time}	_{0.07s (± 4.66%)}	_{0.07s (± 4.13%)}	_{-0.00s (- 1.37%)}	_0.07s	_0.08s
_{Total Time}	_{5.38s (± 0.36%)}	_{5.38s (± 0.41%)}	_{+0.01s (+ 0.11%)}	_5.35s	_5.46s

System

_{Machine Name}	_ts-ci-ubuntu
_Platform	_{linux 4.4.0-210-generic}
_Architecture	_x64
_{Available Memory}	_{16 GB}
_{Available Memory}	_{15 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	₅₀₀₂₁	₁₀
_Baseline	_main	₁₀

Developer Information:

Download Benchmark

typescript-bot · 2022-07-23T21:47:05Z

Heya @ahejlsberg, I've run the RWC suite on this PR - assuming you're on the TS core team, you can view the resulting diff here.

typescript-bot · 2022-07-23T21:50:24Z

@ahejlsberg
Great news! no new errors were found between main..refs/pull/50021/merge

typescript-bot · 2022-07-23T21:52:26Z

Hey @ahejlsberg, I've packed this into an installable tgz. You can install it for testing by referencing it in your package.json like so:

{
    "devDependencies": {
        "typescript": "https://typescript.visualstudio.com/cf7ac146-d525-443c-b23c-0d58337efebc/_apis/build/builds/130297/artifacts?artifactName=tgz&fileId=5B6A9298038EC2E4EEE17420D8BA1C609540E927E60F49CC71CBE61DF68A3F3902&fileName=/typescript-4.8.0-insiders.20220723.tgz"
    }
}

and then running npm install.

There is also a playground for this build and an npm module you can use via "typescript": "npm:@typescript-deploys/[email protected]".;

ahejlsberg · 2022-07-24T00:04:54Z

Tests and performance all look good. No new errors, but one error went away in RWC because of better inference. I think this is a good fix.

ahejlsberg · 2022-07-24T00:19:24Z

Latest commit adds more tests that now succeed but previously failed.

jakebailey

Looks great. I should have known that literals needed the same treatment!

(filterType is another helper I need to commit to memory as existing.)

ahejlsberg added 2 commits July 23, 2022 12:16

Properly handle null and undefined in getCommonSupertype

3bf9f8e

Add tests

d4a239c

typescript-bot assigned ahejlsberg Jul 23, 2022

typescript-bot added Author: Team For Uncommitted Bug PR for untriaged, rejected, closed or missing bug labels Jul 23, 2022

ahejlsberg requested review from DanielRosenwasser and jakebailey July 23, 2022 20:01

Add more tests

9cf39b7

jakebailey approved these changes Jul 24, 2022

View reviewed changes

jakebailey mentioned this pull request Jul 24, 2022

Ensure common supertype retains nullability in inference #49981

Closed

ahejlsberg merged commit 4026c6f into main Jul 24, 2022

ahejlsberg deleted the fix49938 branch July 24, 2022 15:09

ahejlsberg mentioned this pull request Jul 24, 2022

Inference doesn't find common base type for union with null or undefined - TypeScript 4.8 regression #49938

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Properly handle null and undefined in getCommonSupertype #50021

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Properly handle null and undefined in getCommonSupertype #50021

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