Add fallback logic for generating signatures for unions of array members

[Wesley Wigham (weswigham)]

Fixes#44373

With this PR, when we see a type like (A[] | B[])["member"] and look for signatures on it, and find none, we reconstruct (A | B)[]["member"] and instead look up signatures on that. This only applies to array and tuple types because, well, arrays are special. We treat them as covariant when they're not, and we know their collection-like behavior is consistent. This logic does not apply to any custom subtypes of arrays or array-similar things, like UInt8Array - those may have less or more type parameters that both make the reconstruction difficult and potentially break our expectations on how collection-element-like the type parameters are.

This allows things like this:

// @target: es6interfaceFizz{id: number;fizz: string;}interfaceBuzz{id: number;buzz: string;}([]asFizz[]|Buzz[]).filter(item=>item.id<5);([]asFizz[]|readonlyBuzz[]).filter(item=>item.id<5);([]asFizz[]|Buzz[]).find(item=>item);declarefunctionisFizz(x: unknown): x is Fizz;([]asFizz[]|Buzz[]).find(isFizz);declarefunctionisBuzz(x: unknown): x is Buzz;([]asFizz[]|Buzz[]).find(isBuzz);([]asFizz[]|Buzz[]).every(item=>item.id<5);([]asFizz[]|Buzz[]).reduce(item=>item);([]as[Fizz]|readonly[Buzz?]).filter(item=>item?.id<5);

to all work mostly like you'd expect (with maybe the caveat that output arrays are unions of elements within a single array rather than unions of array types).

I'd say that it's possible to broaden this logic to other types using variance measurement logic and some hearty assumptions about how types behave based on their variance, but I feel much better about it making this an array-only change, at least right now.

[Wesley Wigham (weswigham)]

TypeScript Bot (@typescript-bot) test this
TypeScript Bot (@typescript-bot) run dt
TypeScript Bot (@typescript-bot) test top100
TypeScript Bot (@typescript-bot) perf test this
TypeScript Bot (@typescript-bot) pack this

[TypeScript Bot (typescript-bot)]

Heya Wesley Wigham (@weswigham), I've started to run the tarball bundle task on this PR at 975ba5d. You can monitor the build here.

[TypeScript Bot (typescript-bot)]

Heya Wesley Wigham (@weswigham), I've started to run the perf test suite on this PR at 975ba5d. You can monitor the build here.

Update: The results are in!

[TypeScript Bot (typescript-bot)]

Heya Wesley Wigham (@weswigham), I've started to run the diff-based top-repos suite on this PR at 975ba5d. You can monitor the build here.

Update: The results are in!

[TypeScript Bot (typescript-bot)]

Heya Wesley Wigham (@weswigham), I've started to run the parallelized Definitely Typed test suite on this PR at 975ba5d. You can monitor the build here.

Update: The results are in!

[TypeScript Bot (typescript-bot)]

Heya Wesley Wigham (@weswigham), I've started to run the extended test suite on this PR at 975ba5d. You can monitor the build here.

[TypeScript Bot (typescript-bot)]

Hey Wesley Wigham (@weswigham), 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/150967/artifacts?artifactName=tgz&fileId=4F4F2D50012610DBE83CB94154D5058BACD4A956BBC583BEB5D9E7D7A6B98AC402&fileName=/typescript-5.1.0-insiders.20230324.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/pr-build@5.1.0-pr-53489-6".;

[TypeScript Bot (typescript-bot)]

Wesley Wigham (@weswigham)
The results of the perf run you requested are in!

Here they are:

Compiler

Comparison Report - main..53489

Metric	main	53489	Delta	Best	Worst	p-value
Angular - node (v18.10.0, x64)
Memory used	362,093k (± 0.01%)	362,102k (± 0.01%)	~	362,064k	362,128k	p=0.575 n=6
Parse Time	3.40s (± 0.29%)	3.38s (± 0.49%)	-0.02s (- 0.64%)	3.35s	3.40s	p=0.022 n=6
Bind Time	1.12s (± 0.46%)	1.12s (± 0.00%)	~	1.12s	1.12s	p=0.174 n=6
Check Time	8.72s (± 0.28%)	8.70s (± 0.54%)	~	8.64s	8.76s	p=0.568 n=6
Emit Time	7.54s (± 0.57%)	7.49s (± 0.76%)	~	7.38s	7.55s	p=0.168 n=6
Total Time	20.78s (± 0.28%)	20.69s (± 0.35%)	~	20.62s	20.81s	p=0.064 n=6
Compiler-Unions - node (v18.10.0, x64)
Memory used	193,687k (± 1.63%)	191,777k (± 1.22%)	~	190,763k	196,565k	p=0.575 n=6
Parse Time	1.50s (± 0.60%)	1.49s (± 0.78%)	~	1.48s	1.51s	p=0.214 n=6
Bind Time	0.77s (± 0.97%)	0.77s (± 0.67%)	~	0.76s	0.77s	p=0.241 n=6
Check Time	9.66s (± 0.53%)	9.71s (± 0.76%)	~	9.60s	9.78s	p=0.334 n=6
Emit Time	2.73s (± 0.89%)	2.71s (± 0.28%)	~	2.70s	2.72s	p=0.331 n=6
Total Time	14.66s (± 0.53%)	14.68s (± 0.57%)	~	14.57s	14.78s	p=0.748 n=6
Monaco - node (v18.10.0, x64)
Memory used	346,449k (± 0.01%)	346,442k (± 0.01%)	~	346,363k	346,502k	p=1.000 n=6
Parse Time	2.60s (± 0.45%)	2.60s (± 1.01%)	~	2.56s	2.63s	p=0.513 n=6
Bind Time	1.00s (± 0.51%)	1.01s (± 1.03%)	~	1.00s	1.03s	p=0.051 n=6
Check Time	7.14s (± 0.44%)	7.11s (± 0.39%)	~	7.07s	7.14s	p=0.418 n=6
Emit Time	4.25s (± 0.59%)	4.26s (± 0.38%)	~	4.23s	4.28s	p=0.870 n=6
Total Time	14.99s (± 0.35%)	14.98s (± 0.13%)	~	14.96s	15.01s	p=0.627 n=6
TFS - node (v18.10.0, x64)
Memory used	300,672k (± 0.01%)	300,691k (± 0.01%)	~	300,675k	300,728k	p=0.230 n=6
Parse Time	2.08s (± 0.77%)	2.06s (± 1.43%)	~	2.01s	2.09s	p=0.323 n=6
Bind Time	1.14s (± 0.55%)	1.14s (± 0.66%)	~	1.13s	1.15s	p=0.718 n=6
Check Time	6.55s (± 0.48%)	6.54s (± 0.69%)	~	6.47s	6.59s	p=1.000 n=6
Emit Time	3.86s (± 0.35%)	3.84s (± 0.97%)	~	3.80s	3.89s	p=0.293 n=6
Total Time	13.63s (± 0.34%)	13.58s (± 0.74%)	~	13.41s	13.71s	p=0.371 n=6
material-ui - node (v18.10.0, x64)
Memory used	477,137k (± 0.01%)	477,122k (± 0.01%)	~	477,096k	477,167k	p=0.521 n=6
Parse Time	3.01s (± 2.10%)	2.99s (± 2.79%)	~	2.91s	3.11s	p=0.575 n=6
Bind Time	1.02s (± 7.50%)	0.99s (± 8.85%)	~	0.91s	1.08s	p=0.685 n=6
Check Time	17.45s (± 1.04%)	17.13s (± 0.45%)	-0.32s (- 1.82%)	17.06s	17.27s	p=0.008 n=6
Emit Time	0.00s (± 0.00%)	0.00s (± 0.00%)	~	0.00s	0.00s	p=1.000 n=6
Total Time	21.48s (± 0.89%)	21.12s (± 0.45%)	-0.36s (- 1.68%)	20.99s	21.27s	p=0.008 n=6
xstate - node (v18.10.0, x64)
Memory used	552,893k (± 0.02%)	552,929k (± 0.02%)	~	552,827k	553,060k	p=0.521 n=6
Parse Time	3.80s (± 0.59%)	3.79s (± 0.80%)	~	3.75s	3.82s	p=0.331 n=6
Bind Time	1.71s (± 0.68%)	1.70s (± 0.61%)	~	1.69s	1.72s	p=0.241 n=6
Check Time	2.87s (± 0.92%)	2.86s (± 0.41%)	~	2.84s	2.87s	p=0.936 n=6
Emit Time	0.08s (± 0.00%)	0.08s (± 0.00%)	~	0.08s	0.08s	p=1.000 n=6
Total Time	8.47s (± 0.60%)	8.43s (± 0.43%)	~	8.38s	8.47s	p=0.296 n=6
Angular - node (v16.17.1, x64)
Memory used	361,441k (± 0.01%)	361,452k (± 0.01%)	~	361,428k	361,503k	p=0.521 n=6
Parse Time	3.52s (± 0.47%)	3.53s (± 0.87%)	~	3.51s	3.59s	p=0.933 n=6
Bind Time	1.19s (± 0.69%)	1.19s (± 0.63%)	~	1.18s	1.20s	p=0.729 n=6
Check Time	9.55s (± 0.55%)	9.52s (± 0.53%)	~	9.46s	9.58s	p=0.296 n=6
Emit Time	7.96s (± 0.99%)	7.93s (± 0.34%)	~	7.89s	7.96s	p=0.686 n=6
Total Time	22.22s (± 0.60%)	22.16s (± 0.20%)	~	22.09s	22.22s	p=0.810 n=6
Compiler-Unions - node (v16.17.1, x64)
Memory used	193,061k (± 0.72%)	192,525k (± 0.02%)	~	192,486k	192,573k	p=0.298 n=6
Parse Time	1.58s (± 1.26%)	1.59s (± 0.66%)	~	1.58s	1.61s	p=0.217 n=6
Bind Time	0.82s (± 0.50%)	0.82s (± 0.50%)	~	0.82s	0.83s	p=1.000 n=6
Check Time	10.37s (± 0.65%)	10.34s (± 0.34%)	~	10.30s	10.40s	p=0.295 n=6
Emit Time	3.00s (± 0.86%)	2.99s (± 0.65%)	~	2.97s	3.02s	p=0.414 n=6
Total Time	15.78s (± 0.58%)	15.76s (± 0.32%)	~	15.70s	15.83s	p=0.520 n=6
Monaco - node (v16.17.1, x64)
Memory used	345,732k (± 0.01%)	345,727k (± 0.01%)	~	345,707k	345,761k	p=0.689 n=6
Parse Time	2.74s (± 1.32%)	2.73s (± 0.54%)	~	2.72s	2.76s	p=0.566 n=6
Bind Time	1.08s (± 1.26%)	1.09s (± 0.58%)	~	1.08s	1.10s	p=0.388 n=6
Check Time	7.82s (± 0.39%)	7.82s (± 0.61%)	~	7.77s	7.90s	p=0.469 n=6
Emit Time	4.48s (± 0.94%)	4.48s (± 1.08%)	~	4.42s	4.55s	p=1.000 n=6
Total Time	16.12s (± 0.54%)	16.11s (± 0.61%)	~	16.01s	16.27s	p=0.688 n=6
TFS - node (v16.17.1, x64)
Memory used	300,022k (± 0.01%)	300,021k (± 0.00%)	~	300,000k	300,035k	p=0.936 n=6
Parse Time	2.19s (± 0.80%)	2.17s (± 0.39%)	-0.02s (- 0.99%)	2.16s	2.18s	p=0.016 n=6
Bind Time	1.24s (± 1.18%)	1.24s (± 1.19%)	~	1.22s	1.25s	p=0.737 n=6
Check Time	7.22s (± 0.82%)	7.21s (± 0.44%)	~	7.16s	7.26s	p=1.000 n=6
Emit Time	4.32s (± 1.00%)	4.32s (± 0.63%)	~	4.29s	4.36s	p=0.936 n=6
Total Time	14.97s (± 0.64%)	14.93s (± 0.21%)	~	14.88s	14.97s	p=0.336 n=6
material-ui - node (v16.17.1, x64)
Memory used	476,422k (± 0.01%)	476,431k (± 0.01%)	~	476,389k	476,488k	p=0.936 n=6
Parse Time	3.20s (± 1.21%)	3.20s (± 1.14%)	~	3.13s	3.23s	p=0.871 n=6
Bind Time	0.97s (± 2.06%)	0.96s (± 1.02%)	~	0.95s	0.98s	p=0.591 n=6
Check Time	18.14s (± 0.63%)	18.26s (± 0.64%)	~	18.11s	18.42s	p=0.228 n=6
Emit Time	0.00s (± 0.00%)	0.00s (± 0.00%)	~	0.00s	0.00s	p=1.000 n=6
Total Time	22.31s (± 0.48%)	22.42s (± 0.61%)	~	22.25s	22.61s	p=0.173 n=6
xstate - node (v16.17.1, x64)
Memory used	550,479k (± 0.01%)	550,541k (± 0.02%)	~	550,464k	550,797k	p=0.748 n=6
Parse Time	3.95s (± 0.49%)	3.94s (± 0.30%)	~	3.93s	3.96s	p=0.226 n=6
Bind Time	1.79s (± 0.82%)	1.79s (± 0.45%)	~	1.78s	1.80s	p=1.000 n=6
Check Time	3.11s (± 0.64%)	3.10s (± 0.41%)	~	3.08s	3.11s	p=0.462 n=6
Emit Time	0.09s (± 4.45%)	0.09s (± 4.45%)	~	0.09s	0.10s	p=1.000 n=6
Total Time	8.94s (± 0.36%)	8.92s (± 0.34%)	~	8.88s	8.96s	p=0.521 n=6
Angular - node (v14.15.1, x64)
Memory used	355,325k (± 0.00%)	355,333k (± 0.00%)	~	355,323k	355,338k	p=0.128 n=6
Parse Time	3.63s (± 0.81%)	3.58s (± 0.23%)	-0.04s (- 1.15%)	3.58s	3.60s	p=0.011 n=6
Bind Time	1.23s (± 0.89%)	1.23s (± 0.61%)	~	1.22s	1.24s	p=1.000 n=6
Check Time	9.92s (± 0.24%)	9.90s (± 0.36%)	~	9.83s	9.93s	p=0.416 n=6
Emit Time	8.36s (± 0.65%)	8.35s (± 1.06%)	~	8.27s	8.50s	p=0.469 n=6
Total Time	23.13s (± 0.20%)	23.06s (± 0.44%)	~	22.94s	23.23s	p=0.173 n=6
Compiler-Unions - node (v14.15.1, x64)
Memory used	187,755k (± 0.01%)	188,212k (± 0.62%)	~	187,556k	190,602k	p=0.378 n=6
Parse Time	1.61s (± 0.75%)	1.61s (± 0.85%)	~	1.59s	1.63s	p=1.000 n=6
Bind Time	0.85s (± 1.15%)	0.85s (± 0.74%)	~	0.84s	0.86s	p=1.000 n=6
Check Time	10.50s (± 0.73%)	10.52s (± 0.47%)	~	10.45s	10.60s	p=0.871 n=6
Emit Time	3.12s (± 0.43%)	3.20s (± 3.64%)	~	3.11s	3.42s	p=0.221 n=6
Total Time	16.07s (± 0.44%)	16.17s (± 0.72%)	~	16.03s	16.37s	p=0.173 n=6
Monaco - node (v14.15.1, x64)
Memory used	340,596k (± 0.01%)	340,629k (± 0.00%)	+33k (+ 0.01%)	340,607k	340,641k	p=0.020 n=6
Parse Time	2.84s (± 0.35%)	2.82s (± 0.43%)	-0.02s (- 0.88%)	2.80s	2.83s	p=0.011 n=6
Bind Time	1.11s (± 0.95%)	1.10s (± 0.37%)	~	1.09s	1.10s	p=0.209 n=6
Check Time	8.17s (± 0.48%)	8.17s (± 0.33%)	~	8.14s	8.20s	p=1.000 n=6
Emit Time	4.68s (± 0.92%)	4.69s (± 0.59%)	~	4.66s	4.73s	p=0.469 n=6
Total Time	16.80s (± 0.36%)	16.78s (± 0.25%)	~	16.75s	16.86s	p=0.293 n=6
TFS - node (v14.15.1, x64)
Memory used	295,093k (± 0.01%)	295,088k (± 0.01%)	~	295,058k	295,114k	p=0.748 n=6
Parse Time	2.40s (± 0.73%)	2.38s (± 0.49%)	~	2.36s	2.39s	p=0.072 n=6
Bind Time	1.06s (± 0.38%)	1.06s (± 0.49%)	~	1.06s	1.07s	p=0.595 n=6
Check Time	7.52s (± 0.72%)	7.50s (± 0.16%)	~	7.49s	7.52s	p=0.327 n=6
Emit Time	4.30s (± 0.80%)	4.28s (± 0.34%)	~	4.26s	4.30s	p=0.259 n=6
Total Time	15.29s (± 0.38%)	15.22s (± 0.20%)	~	15.17s	15.25s	p=0.090 n=6
material-ui - node (v14.15.1, x64)
Memory used	471,990k (± 0.00%)	471,947k (± 0.00%)	-43k (- 0.01%)	471,911k	471,969k	p=0.013 n=6
Parse Time	3.36s (± 0.51%)	3.35s (± 0.51%)	~	3.33s	3.38s	p=0.411 n=6
Bind Time	1.01s (± 0.51%)	1.00s (± 0.82%)	-0.01s (- 0.99%)	0.99s	1.01s	p=0.050 n=6
Check Time	19.20s (± 0.61%)	19.10s (± 0.19%)	~	19.04s	19.13s	p=0.065 n=6
Emit Time	0.00s (± 0.00%)	0.00s (± 0.00%)	~	0.00s	0.00s	p=1.000 n=6
Total Time	23.57s (± 0.49%)	23.45s (± 0.24%)	~	23.36s	23.52s	p=0.054 n=6
xstate - node (v14.15.1, x64)
Memory used	539,174k (± 0.00%)	539,200k (± 0.00%)	~	539,171k	539,225k	p=0.127 n=6
Parse Time	4.24s (± 0.41%)	4.24s (± 0.82%)	~	4.20s	4.29s	p=0.629 n=6
Bind Time	1.68s (± 0.58%)	1.69s (± 0.90%)	~	1.67s	1.71s	p=0.801 n=6
Check Time	3.22s (± 0.48%)	3.23s (± 0.73%)	~	3.19s	3.25s	p=0.684 n=6
Emit Time	0.09s (± 0.00%)	0.09s (± 0.00%)	~	0.09s	0.09s	p=1.000 n=6
Total Time	9.22s (± 0.14%)	9.24s (± 0.78%)	~	9.15s	9.32s	p=1.000 n=6

System

Machine Name	ts-ci-ubuntu
Platform	linux 5.4.0-135-generic
Architecture	x64
Available Memory	16 GB
Available Memory	15 GB
CPUs	4 × Intel(R) Core(TM) i7-4770 CPU @ 3.40GHz

Hosts

• node (v18.10.0, x64)
• node (v16.17.1, x64)
• node (v14.15.1, x64)

Scenarios

• Angular - node (v18.10.0, x64)
• Angular - node (v16.17.1, x64)
• Angular - node (v14.15.1, x64)
• Compiler-Unions - node (v18.10.0, x64)
• Compiler-Unions - node (v16.17.1, x64)
• Compiler-Unions - node (v14.15.1, x64)
• Monaco - node (v18.10.0, x64)
• Monaco - node (v16.17.1, x64)
• Monaco - node (v14.15.1, x64)
• TFS - node (v18.10.0, x64)
• TFS - node (v16.17.1, x64)
• TFS - node (v14.15.1, x64)
• material-ui - node (v18.10.0, x64)
• material-ui - node (v16.17.1, x64)
• material-ui - node (v14.15.1, x64)
• xstate - node (v18.10.0, x64)
• xstate - node (v16.17.1, x64)
• xstate - node (v14.15.1, x64)

Benchmark	Name	Iterations
Current	53489	6
Baseline	main	6

TSServer

Comparison Report - main..53489

Metric	main	53489	Delta	Best	Worst	p-value
Compiler-UnionsTSServer - node (v18.10.0, x64)
Req 1 - updateOpen	2,402ms (± 0.64%)	2,391ms (± 0.52%)	~	2,372ms	2,411ms	p=0.423 n=6
Req 2 - geterr	5,525ms (± 0.37%)	5,545ms (± 0.51%)	~	5,513ms	5,595ms	p=0.298 n=6
Req 3 - references	338ms (± 1.66%)	338ms (± 1.55%)	~	334ms	348ms	p=1.000 n=6
Req 4 - navto	281ms (± 0.35%)	280ms (± 0.60%)	~	278ms	282ms	p=0.318 n=6
Req 5 - completionInfo count	1,356 (± 0.00%)	1,356 (± 0.00%)	~	1,356	1,356	p=1.000 n=6
Req 5 - completionInfo	82ms (± 3.53%)	83ms (± 2.73%)	~	78ms	84ms	p=1.000 n=6
CompilerTSServer - node (v18.10.0, x64)
Req 1 - updateOpen	2,534ms (± 1.20%)	2,545ms (± 1.36%)	~	2,502ms	2,591ms	p=0.471 n=6
Req 2 - geterr	4,066ms (± 0.48%)	4,070ms (± 0.56%)	~	4,042ms	4,103ms	p=0.748 n=6
Req 3 - references	349ms (± 1.60%)	352ms (± 0.47%)	~	350ms	354ms	p=0.685 n=6
Req 4 - navto	289ms (± 0.68%)	289ms (± 0.90%)	~	285ms	293ms	p=1.000 n=6
Req 5 - completionInfo count	1,518 (± 0.00%)	1,518 (± 0.00%)	~	1,518	1,518	p=1.000 n=6
Req 5 - completionInfo	78ms (± 7.29%)	80ms (± 3.98%)	~	76ms	86ms	p=0.798 n=6
xstateTSServer - node (v18.10.0, x64)
Req 1 - updateOpen	3,026ms (± 0.64%)	3,018ms (± 1.00%)	~	2,984ms	3,061ms	p=0.810 n=6
Req 2 - geterr	1,695ms (± 1.79%)	1,704ms (± 0.79%)	~	1,680ms	1,719ms	p=0.173 n=6
Req 3 - references	107ms (± 0.59%)	107ms (± 1.38%)	~	104ms	108ms	p=0.787 n=6
Req 4 - navto	358ms (± 0.66%)	357ms (± 0.60%)	~	355ms	360ms	p=0.627 n=6
Req 5 - completionInfo count	2,861 (± 0.00%)	2,861 (± 0.00%)	~	2,861	2,861	p=1.000 n=6
Req 5 - completionInfo	381ms (± 2.07%)	393ms (± 5.30%)	~	379ms	433ms	p=0.261 n=6
Compiler-UnionsTSServer - node (v16.17.1, x64)
Req 1 - updateOpen	2,511ms (± 0.89%)	2,517ms (± 1.26%)	~	2,480ms	2,571ms	p=0.936 n=6
Req 2 - geterr	5,892ms (± 0.17%)	5,906ms (± 0.55%)	~	5,870ms	5,965ms	p=0.335 n=6
Req 3 - references	347ms (± 0.66%)	349ms (± 1.06%)	~	346ms	356ms	p=0.519 n=6
Req 4 - navto	279ms (± 0.27%)	278ms (± 0.78%)	~	274ms	280ms	p=0.858 n=6
Req 5 - completionInfo count	1,356 (± 0.00%)	1,356 (± 0.00%)	~	1,356	1,356	p=1.000 n=6
Req 5 - completionInfo	74ms (± 1.57%)	72ms (± 1.43%)	-2ms (- 2.47%)	71ms	74ms	p=0.032 n=6
CompilerTSServer - node (v16.17.1, x64)
Req 1 - updateOpen	2,676ms (± 0.51%)	2,665ms (± 0.34%)	~	2,651ms	2,673ms	p=0.172 n=6
Req 2 - geterr	4,438ms (± 0.36%)	4,439ms (± 0.46%)	~	4,406ms	4,456ms	p=0.689 n=6
Req 3 - references	365ms (± 0.24%)	366ms (± 0.65%)	~	363ms	368ms	p=0.373 n=6
Req 4 - navto	287ms (± 0.22%)	287ms (± 0.26%)	~	286ms	288ms	p=0.718 n=6
Req 5 - completionInfo count	1,518 (± 0.00%)	1,518 (± 0.00%)	~	1,518	1,518	p=1.000 n=6
Req 5 - completionInfo	78ms (± 3.19%)	78ms (± 2.74%)	~	76ms	81ms	p=0.933 n=6
xstateTSServer - node (v16.17.1, x64)
Req 1 - updateOpen	3,160ms (± 0.35%)	3,161ms (± 0.50%)	~	3,143ms	3,185ms	p=1.000 n=6
Req 2 - geterr	1,845ms (± 0.71%)	1,861ms (± 0.89%)	~	1,834ms	1,875ms	p=0.092 n=6
Req 3 - references	114ms (± 1.65%)	114ms (± 1.98%)	~	112ms	118ms	p=1.000 n=6
Req 4 - navto	342ms (± 0.39%)	341ms (± 0.48%)	~	339ms	343ms	p=0.216 n=6
Req 5 - completionInfo count	2,861 (± 0.00%)	2,861 (± 0.00%)	~	2,861	2,861	p=1.000 n=6
Req 5 - completionInfo	393ms (± 1.06%)	401ms (± 0.82%)	+9ms (+ 2.16%)	397ms	405ms	p=0.006 n=6
Compiler-UnionsTSServer - node (v14.15.1, x64)
Req 1 - updateOpen	2,607ms (± 0.52%)	2,603ms (± 0.56%)	~	2,584ms	2,621ms	p=0.517 n=6
Req 2 - geterr	6,353ms (± 0.48%)	6,367ms (± 0.43%)	~	6,325ms	6,390ms	p=0.471 n=6
Req 3 - references	362ms (± 0.52%)	364ms (± 0.40%)	~	362ms	366ms	p=0.103 n=6
Req 4 - navto	282ms (± 0.85%)	282ms (± 1.43%)	~	280ms	290ms	p=0.366 n=6
Req 5 - completionInfo count	1,356 (± 0.00%)	1,356 (± 0.00%)	~	1,356	1,356	p=1.000 n=6
Req 5 - completionInfo	96ms (± 6.11%)	101ms (± 2.06%)	~	98ms	103ms	p=0.371 n=6
CompilerTSServer - node (v14.15.1, x64)
Req 1 - updateOpen	2,831ms (± 0.59%)	2,825ms (± 0.59%)	~	2,804ms	2,847ms	p=0.630 n=6
Req 2 - geterr	4,684ms (± 2.62%)	4,716ms (± 2.42%)	~	4,560ms	4,807ms	p=0.810 n=6
Req 3 - references	389ms (± 6.97%)	379ms (± 5.51%)	~	368ms	421ms	p=0.466 n=6
Req 4 - navto	289ms (± 1.08%)	292ms (± 1.62%)	~	285ms	297ms	p=0.361 n=6
Req 5 - completionInfo count	1,518 (± 0.00%)	1,518 (± 0.00%)	~	1,518	1,518	p=1.000 n=6
Req 5 - completionInfo	80ms (± 9.99%)	78ms (± 9.21%)	~	74ms	92ms	p=0.366 n=6
xstateTSServer - node (v14.15.1, x64)
Req 1 - updateOpen	3,458ms (± 0.44%)	3,444ms (± 0.42%)	~	3,421ms	3,461ms	p=0.298 n=6
Req 2 - geterr	1,869ms (± 1.26%)	1,890ms (± 1.11%)	~	1,854ms	1,917ms	p=0.149 n=6
Req 3 - references	125ms (± 0.60%)	125ms (± 1.60%)	~	123ms	128ms	p=0.676 n=6
Req 4 - navto	372ms (± 0.53%)	370ms (± 0.33%)	~	369ms	372ms	p=0.285 n=6
Req 5 - completionInfo count	2,861 (± 0.00%)	2,861 (± 0.00%)	~	2,861	2,861	p=1.000 n=6
Req 5 - completionInfo	408ms (± 1.22%)	406ms (± 0.90%)	~	401ms	411ms	p=0.574 n=6

System

Machine Name	ts-ci-ubuntu
Platform	linux 5.4.0-135-generic
Architecture	x64
Available Memory	16 GB
Available Memory	15 GB
CPUs	4 × Intel(R) Core(TM) i7-4770 CPU @ 3.40GHz

Hosts

• node (v18.10.0, x64)
• node (v16.17.1, x64)
• node (v14.15.1, x64)

Scenarios

• Compiler-UnionsTSServer - node (v18.10.0, x64)
• Compiler-UnionsTSServer - node (v16.17.1, x64)
• Compiler-UnionsTSServer - node (v14.15.1, x64)
• CompilerTSServer - node (v18.10.0, x64)
• CompilerTSServer - node (v16.17.1, x64)
• CompilerTSServer - node (v14.15.1, x64)
• xstateTSServer - node (v18.10.0, x64)
• xstateTSServer - node (v16.17.1, x64)
• xstateTSServer - node (v14.15.1, x64)

Benchmark	Name	Iterations
Current	53489	6
Baseline	main	6

Startup

Comparison Report - main..53489

Metric	main	53489	Delta	Best	Worst	p-value
tsc-startup - node (v16.17.1, x64)
Execution time	141.87ms (± 0.23%)	141.27ms (± 0.20%)	-0.60ms (- 0.43%)	140.63ms	146.58ms	p=0.000 n=600
tsserver-startup - node (v16.17.1, x64)
Execution time	229.11ms (± 0.47%)	227.22ms (± 0.41%)	-1.89ms (- 0.83%)	224.85ms	233.56ms	p=0.000 n=600
tsserverlibrary-startup - node (v16.17.1, x64)
Execution time	230.78ms (± 0.38%)	227.97ms (± 0.20%)	-2.81ms (- 1.22%)	226.74ms	232.94ms	p=0.000 n=600
typescript-startup - node (v16.17.1, x64)
Execution time	210.94ms (± 0.35%)	209.10ms (± 0.23%)	-1.85ms (- 0.88%)	207.82ms	216.36ms	p=0.000 n=600

System

Machine Name	ts-ci-ubuntu
Platform	linux 5.4.0-135-generic
Architecture	x64
Available Memory	16 GB
Available Memory	15 GB
CPUs	4 × Intel(R) Core(TM) i7-4770 CPU @ 3.40GHz

Hosts

• node (v16.17.1, x64)

Scenarios

• tsc-startup - node (v16.17.1, x64)
• tsserver-startup - node (v16.17.1, x64)
• tsserverlibrary-startup - node (v16.17.1, x64)
• typescript-startup - node (v16.17.1, x64)

Benchmark	Name	Iterations
Current	53489	6
Baseline	main	6

Developer Information:

Download Benchmark

[TypeScript Bot (typescript-bot)]

Hey Wesley Wigham (@weswigham), the results of running the DT tests are ready.
Everything looks the same!
You can check the log here.

[TypeScript Bot (typescript-bot)]

Wesley Wigham (@weswigham) Here are the results of running the top-repos suite comparing main and refs/pull/53489/merge:

Everything looks good!

[Eric Ferreira (ericbf)]

with maybe the caveat that output arrays are unions of elements within a single array rather than unions of array types

This is kind of a big caveat, don’t you think? Filter, for example, doesn’t change the type of the array, so for it to convert A[] | B[] to (A | B)[] is very weird and could be classified as a bug if merged as is, imo. Under no normal circumstances ever would (A[] | B[]).filter return a (A | B)[]...

[Ryan Cavanaugh (RyanCavanaugh)]

This is kind of a big caveat, don’t you think?

I'm not sure what the proposed alternative is. If you're writing filter, you're probably writing arr.filter(x => expr), and we can't iteratively assign a type to x -- it needs to be a single type, ideally A | B.

[Eric Ferreira (ericbf)]

I'm not sure what the proposed alternative is. If you're writing filter, you're probably writing arr.filter(x => expr), and we can't iteratively assign a type to x -- it needs to be a single type, ideally A | B.

For filter (and even if only for filter), I’d expect the type to be something like:

// Assuming the array is `A[] | B[]`(predicate: (item: A|B,index: number,array: A[]|B[])=>boolean)=>A[]|B[]

The type of the item in the predicate could be either A or B, but the returned array from filter would only ever be an A[] or a B[].

Granted, this current implemented is definitely a step in the right direction, much better than not working at all.

[Wesley Wigham (weswigham)]

TypeScript Bot (@typescript-bot) pack this

[TypeScript Bot (typescript-bot)]

Heya Wesley Wigham (@weswigham), I've started to run the tarball bundle task on this PR at 975ba5d. You can monitor the build here.

[TypeScript Bot (typescript-bot)]

Hey Wesley Wigham (@weswigham), 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/152278/artifacts?artifactName=tgz&fileId=F51ABFB5B241623909891BC82EFFA0E7BC9A352A55A35004D867C9BD4598367002&fileName=/typescript-5.1.0-insiders.20230412.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/pr-build@5.1.0-pr-53489-15".;

[Wesley Wigham (weswigham)]

Andrew Branch (@andrewbranch)Anders Hejlsberg (@ahejlsberg) I'm pinging more people for a second review :)

[Daniel Rosenwasser (DanielRosenwasser)]

TypeScript Bot (@typescript-bot) pack this
TypeScript Bot (@typescript-bot) test this
TypeScript Bot (@typescript-bot) test top100
TypeScript Bot (@typescript-bot) user test this
TypeScript Bot (@typescript-bot) user test tsserver
TypeScript Bot (@typescript-bot) test tsserver top100
TypeScript Bot (@typescript-bot) run dt
TypeScript Bot (@typescript-bot) perf test this

[TypeScript Bot (typescript-bot)]

Heya Daniel Rosenwasser (@DanielRosenwasser), I've started to run the diff-based top-repos suite on this PR at 975ba5d. You can monitor the build here.

Update: The results are in!

[TypeScript Bot (typescript-bot)]

Heya Daniel Rosenwasser (@DanielRosenwasser), I've started to run the diff-based user code test suite (tsserver) on this PR at 975ba5d. You can monitor the build here.

Update: The results are in!

[TypeScript Bot (typescript-bot)]

Heya Daniel Rosenwasser (@DanielRosenwasser), I've started to run the diff-based top-repos suite (tsserver) on this PR at 975ba5d. You can monitor the build here.

Update: The results are in!

[TypeScript Bot (typescript-bot)]

Heya Daniel Rosenwasser (@DanielRosenwasser), I've started to run the tarball bundle task on this PR at 975ba5d. You can monitor the build here.

[TypeScript Bot (typescript-bot)]

Heya Daniel Rosenwasser (@DanielRosenwasser), I've started to run the perf test suite on this PR at 975ba5d. You can monitor the build here.

Update: The results are in!

[TypeScript Bot (typescript-bot)]

Heya Daniel Rosenwasser (@DanielRosenwasser), I've started to run the extended test suite on this PR at 975ba5d. You can monitor the build here.

[TypeScript Bot (typescript-bot)]

Heya Daniel Rosenwasser (@DanielRosenwasser), I've started to run the diff-based user code test suite on this PR at 975ba5d. You can monitor the build here.

Update: The results are in!

[TypeScript Bot (typescript-bot)]

Hey Daniel Rosenwasser (@DanielRosenwasser), 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/152478/artifacts?artifactName=tgz&fileId=8E69FF64CF161684D70F57887E9994B4BD0AD738117AA41749CFA3AE1476B7F202&fileName=/typescript-5.1.0-insiders.20230415.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/pr-build@5.1.0-pr-53489-26".;

[TypeScript Bot (typescript-bot)]

Daniel Rosenwasser (@DanielRosenwasser) Here are the results of running the user test suite comparing main and refs/pull/53489/merge:

There were infrastructure failures potentially unrelated to your change:

• 1 instance of "Package install failed"

Otherwise...

Everything looks good!

[TypeScript Bot (typescript-bot)]

Daniel Rosenwasser (@DanielRosenwasser) Here are the results of running the user test suite comparing main and refs/pull/53489/merge:

Everything looks good!

[TypeScript Bot (typescript-bot)]

Daniel Rosenwasser (@DanielRosenwasser) Here are the results of running the top-repos suite comparing main and refs/pull/53489/merge:

Everything looks good!

[TypeScript Bot (typescript-bot)]

Daniel Rosenwasser (@DanielRosenwasser)
The results of the perf run you requested are in!

Here they are:

Compiler

Comparison Report - main..53489

Metric	main	53489	Delta	Best	Worst	p-value
Angular - node (v18.10.0, x64)
Memory used	365,213k (± 0.01%)	365,217k (± 0.01%)	~	365,173k	365,281k	p=0.810 n=6
Parse Time	3.35s (± 0.57%)	3.35s (± 0.70%)	~	3.31s	3.37s	p=0.934 n=6
Bind Time	1.11s (± 1.47%)	1.13s (± 0.93%)	~	1.11s	1.14s	p=0.250 n=6
Check Time	8.72s (± 0.29%)	8.70s (± 0.50%)	~	8.64s	8.75s	p=0.258 n=6
Emit Time	7.44s (± 0.25%)	7.48s (± 0.28%)	+0.04s (+ 0.52%)	7.46s	7.51s	p=0.007 n=6
Total Time	20.63s (± 0.21%)	20.65s (± 0.35%)	~	20.54s	20.74s	p=0.573 n=6
Compiler-Unions - node (v18.10.0, x64)
Memory used	191,342k (± 0.53%)	190,957k (± 0.02%)	~	190,916k	191,002k	p=0.261 n=6
Parse Time	1.49s (± 0.27%)	1.50s (± 0.60%)	+0.01s (+ 0.78%)	1.49s	1.51s	p=0.025 n=6
Bind Time	0.77s (± 0.53%)	0.77s (± 0.98%)	~	0.76s	0.78s	p=1.000 n=6
Check Time	9.52s (± 0.57%)	9.55s (± 0.37%)	~	9.51s	9.59s	p=0.334 n=6
Emit Time	2.73s (± 1.24%)	2.74s (± 1.12%)	~	2.71s	2.79s	p=0.565 n=6
Total Time	14.50s (± 0.49%)	14.55s (± 0.32%)	~	14.49s	14.61s	p=0.199 n=6
Monaco - node (v18.10.0, x64)
Memory used	346,495k (± 0.01%)	346,516k (± 0.01%)	~	346,488k	346,562k	p=0.173 n=6
Parse Time	2.59s (± 0.73%)	2.57s (± 1.76%)	~	2.53s	2.63s	p=0.629 n=6
Bind Time	1.01s (± 0.63%)	1.00s (± 0.41%)	-0.01s (- 0.83%)	1.00s	1.01s	p=0.033 n=6
Check Time	7.13s (± 0.49%)	7.12s (± 0.30%)	~	7.09s	7.15s	p=0.334 n=6
Emit Time	4.24s (± 0.55%)	4.26s (± 0.95%)	~	4.23s	4.34s	p=0.255 n=6
Total Time	14.97s (± 0.44%)	14.96s (± 0.42%)	~	14.90s	15.04s	p=1.000 n=6
TFS - node (v18.10.0, x64)
Memory used	300,717k (± 0.01%)	300,703k (± 0.01%)	~	300,686k	300,743k	p=0.336 n=6
Parse Time	2.04s (± 1.34%)	2.06s (± 1.11%)	~	2.04s	2.10s	p=0.295 n=6
Bind Time	1.14s (± 1.24%)	1.14s (± 0.55%)	~	1.13s	1.15s	p=1.000 n=6
Check Time	6.53s (± 0.51%)	6.53s (± 0.34%)	~	6.49s	6.55s	p=0.808 n=6
Emit Time	3.86s (± 0.81%)	3.86s (± 1.20%)	~	3.81s	3.92s	p=0.871 n=6
Total Time	13.58s (± 0.51%)	13.59s (± 0.34%)	~	13.53s	13.66s	p=0.572 n=6
material-ui - node (v18.10.0, x64)
Memory used	481,862k (± 0.01%)	481,833k (± 0.00%)	~	481,810k	481,856k	p=0.127 n=6
Parse Time	3.03s (± 0.70%)	3.03s (± 0.54%)	~	3.01s	3.05s	p=0.745 n=6
Bind Time	0.91s (± 2.56%)	0.91s (± 1.61%)	~	0.90s	0.94s	p=0.796 n=6
Check Time	16.77s (± 0.46%)	16.82s (± 0.58%)	~	16.72s	16.98s	p=0.378 n=6
Emit Time	0.00s (± 0.00%)	0.00s (± 0.00%)	~	0.00s	0.00s	p=1.000 n=6
Total Time	20.72s (± 0.29%)	20.77s (± 0.50%)	~	20.66s	20.94s	p=0.521 n=6
xstate - node (v18.10.0, x64)
Memory used	561,801k (± 0.02%)	561,819k (± 0.03%)	~	561,645k	562,132k	p=0.936 n=6
Parse Time	3.81s (± 0.91%)	3.82s (± 0.52%)	~	3.80s	3.85s	p=0.418 n=6
Bind Time	1.65s (± 0.71%)	1.65s (± 0.46%)	~	1.64s	1.66s	p=0.933 n=6
Check Time	2.80s (± 0.73%)	2.80s (± 1.07%)	~	2.77s	2.84s	p=0.936 n=6
Emit Time	0.08s (± 0.00%)	0.08s (± 0.00%)	~	0.08s	0.08s	p=1.000 n=6
Total Time	8.34s (± 0.65%)	8.36s (± 0.44%)	~	8.31s	8.41s	p=0.688 n=6
Angular - node (v16.17.1, x64)
Memory used	364,602k (± 0.00%)	364,606k (± 0.01%)	~	364,582k	364,636k	p=0.688 n=6
Parse Time	3.54s (± 0.71%)	3.54s (± 0.79%)	~	3.50s	3.57s	p=0.807 n=6
Bind Time	1.18s (± 1.39%)	1.18s (± 0.76%)	~	1.17s	1.19s	p=0.560 n=6
Check Time	9.50s (± 0.32%)	9.47s (± 0.29%)	~	9.44s	9.51s	p=0.225 n=6
Emit Time	7.92s (± 0.68%)	7.95s (± 0.40%)	~	7.91s	7.99s	p=0.125 n=6
Total Time	22.14s (± 0.26%)	22.15s (± 0.25%)	~	22.05s	22.19s	p=0.809 n=6
Compiler-Unions - node (v16.17.1, x64)
Memory used	193,129k (± 0.69%)	192,613k (± 0.03%)	~	192,537k	192,666k	p=0.810 n=6
Parse Time	1.59s (± 0.51%)	1.57s (± 1.86%)	~	1.53s	1.60s	p=0.532 n=6
Bind Time	0.82s (± 0.50%)	0.82s (± 0.66%)	~	0.82s	0.83s	p=0.282 n=6
Check Time	10.22s (± 0.44%)	10.24s (± 0.64%)	~	10.12s	10.31s	p=0.227 n=6
Emit Time	2.99s (± 0.72%)	3.00s (± 0.93%)	~	2.97s	3.05s	p=0.290 n=6
Total Time	15.61s (± 0.31%)	15.64s (± 0.44%)	~	15.53s	15.72s	p=0.336 n=6
Monaco - node (v16.17.1, x64)
Memory used	345,786k (± 0.01%)	345,792k (± 0.01%)	~	345,769k	345,821k	p=0.521 n=6
Parse Time	2.72s (± 0.19%)	2.72s (± 0.43%)	~	2.71s	2.74s	p=0.929 n=6
Bind Time	1.08s (± 0.48%)	1.08s (± 0.70%)	~	1.07s	1.09s	p=0.784 n=6
Check Time	7.85s (± 0.31%)	7.83s (± 0.50%)	~	7.80s	7.90s	p=0.107 n=6
Emit Time	4.48s (± 0.74%)	4.48s (± 0.68%)	~	4.44s	4.52s	p=0.936 n=6
Total Time	16.14s (± 0.30%)	16.11s (± 0.44%)	~	16.06s	16.25s	p=0.260 n=6
TFS - node (v16.17.1, x64)
Memory used	300,051k (± 0.01%)	300,063k (± 0.00%)	~	300,049k	300,082k	p=0.748 n=6
Parse Time	2.16s (± 0.49%)	2.16s (± 0.41%)	~	2.15s	2.17s	p=0.452 n=6
Bind Time	1.24s (± 0.85%)	1.23s (± 1.22%)	~	1.21s	1.25s	p=1.000 n=6
Check Time	7.19s (± 0.43%)	7.16s (± 0.16%)	~	7.15s	7.18s	p=0.084 n=6
Emit Time	4.34s (± 0.51%)	4.33s (± 0.60%)	~	4.29s	4.36s	p=0.686 n=6
Total Time	14.91s (± 0.31%)	14.89s (± 0.32%)	~	14.82s	14.95s	p=0.377 n=6
material-ui - node (v16.17.1, x64)
Memory used	481,178k (± 0.01%)	481,213k (± 0.02%)	~	481,093k	481,298k	p=0.689 n=6
Parse Time	3.24s (± 0.41%)	3.24s (± 0.42%)	~	3.23s	3.27s	p=0.868 n=6
Bind Time	0.95s (± 0.57%)	0.95s (± 0.54%)	-0.01s (- 0.87%)	0.94s	0.95s	p=0.038 n=6
Check Time	17.80s (± 0.43%)	17.84s (± 0.26%)	~	17.76s	17.88s	p=0.261 n=6
Emit Time	0.00s (± 0.00%)	0.00s (± 0.00%)	~	0.00s	0.00s	p=1.000 n=6
Total Time	22.00s (± 0.38%)	22.03s (± 0.19%)	~	21.97s	22.07s	p=0.297 n=6
xstate - node (v16.17.1, x64)
Memory used	559,536k (± 0.03%)	559,468k (± 0.03%)	~	559,336k	559,705k	p=0.574 n=6
Parse Time	3.99s (± 0.25%)	4.00s (± 0.43%)	~	3.98s	4.02s	p=0.154 n=6
Bind Time	1.75s (± 0.43%)	1.75s (± 0.23%)	~	1.75s	1.76s	p=0.389 n=6
Check Time	3.02s (± 0.34%)	3.01s (± 0.18%)	-0.01s (- 0.39%)	3.00s	3.01s	p=0.047 n=6
Emit Time	0.09s (± 0.00%)	0.09s (± 0.00%)	~	0.09s	0.09s	p=1.000 n=6
Total Time	8.84s (± 0.23%)	8.85s (± 0.20%)	~	8.83s	8.88s	p=0.455 n=6

System

Machine Name	ts-ci-ubuntu
Platform	linux 5.4.0-135-generic
Architecture	x64
Available Memory	16 GB
Available Memory	15 GB
CPUs	4 × Intel(R) Core(TM) i7-4770 CPU @ 3.40GHz

Hosts

• node (v18.10.0, x64)
• node (v16.17.1, x64)
• node (v14.21.3, x64)

Scenarios

• Angular - node (v18.10.0, x64)
• Angular - node (v16.17.1, x64)
• Angular - node (v14.21.3, x64)
• Compiler-Unions - node (v18.10.0, x64)
• Compiler-Unions - node (v16.17.1, x64)
• Compiler-Unions - node (v14.21.3, x64)
• Monaco - node (v18.10.0, x64)
• Monaco - node (v16.17.1, x64)
• Monaco - node (v14.21.3, x64)
• TFS - node (v18.10.0, x64)
• TFS - node (v16.17.1, x64)
• TFS - node (v14.21.3, x64)
• material-ui - node (v18.10.0, x64)
• material-ui - node (v16.17.1, x64)
• material-ui - node (v14.21.3, x64)
• xstate - node (v18.10.0, x64)
• xstate - node (v16.17.1, x64)
• xstate - node (v14.21.3, x64)

Benchmark	Name	Iterations
Current	53489	6
Baseline	main	6

TSServer

Comparison Report - main..53489

Metric	main	53489	Delta	Best	Worst	p-value
Compiler-UnionsTSServer - node (v18.10.0, x64)
Req 1 - updateOpen	2,393ms (± 0.32%)	2,407ms (± 0.77%)	~	2,386ms	2,438ms	p=0.149 n=6
Req 2 - geterr	5,605ms (± 0.83%)	5,587ms (± 1.66%)	~	5,412ms	5,662ms	p=0.936 n=6
Req 3 - references	339ms (± 0.48%)	340ms (± 1.14%)	~	338ms	348ms	p=0.511 n=6
Req 4 - navto	284ms (± 0.49%)	286ms (± 1.00%)	~	283ms	291ms	p=0.101 n=6
Req 5 - completionInfo count	1,356 (± 0.00%)	1,356 (± 0.00%)	~	1,356	1,356	p=1.000 n=6
Req 5 - completionInfo	84ms (± 0.75%)	82ms (± 8.61%)	~	68ms	88ms	p=1.000 n=6
CompilerTSServer - node (v18.10.0, x64)
Req 1 - updateOpen	2,504ms (± 1.25%)	2,517ms (± 1.47%)	~	2,471ms	2,555ms	p=0.471 n=6
Req 2 - geterr	4,214ms (± 0.42%)	4,218ms (± 1.30%)	~	4,111ms	4,258ms	p=0.297 n=6
Req 3 - references	343ms (± 0.39%)	351ms (± 5.40%)	~	341ms	390ms	p=0.249 n=6
Req 4 - navto	290ms (± 1.44%)	288ms (± 0.83%)	~	283ms	289ms	p=0.720 n=6
Req 5 - completionInfo count	1,518 (± 0.00%)	1,518 (± 0.00%)	~	1,518	1,518	p=1.000 n=6
Req 5 - completionInfo	64ms (± 4.56%)	65ms (± 5.99%)	~	62ms	70ms	p=0.933 n=6
xstateTSServer - node (v18.10.0, x64)
Req 1 - updateOpen	3,025ms (± 0.38%)	3,018ms (± 0.19%)	~	3,009ms	3,025ms	p=0.295 n=6
Req 2 - geterr	1,597ms (± 0.76%)	1,605ms (± 0.66%)	~	1,598ms	1,626ms	p=0.572 n=6
Req 3 - references	108ms (± 4.05%)	108ms (± 2.68%)	~	105ms	113ms	p=0.622 n=6
Req 4 - navto	364ms (± 0.33%)	362ms (± 0.48%)	~	360ms	364ms	p=0.166 n=6
Req 5 - completionInfo count	2,862 (± 0.00%)	2,862 (± 0.00%)	~	2,862	2,862	p=1.000 n=6
Req 5 - completionInfo	374ms (± 1.34%)	377ms (± 2.25%)	~	362ms	386ms	p=0.261 n=6
Compiler-UnionsTSServer - node (v16.17.1, x64)
Req 1 - updateOpen	2,522ms (± 0.59%)	2,532ms (± 0.69%)	~	2,503ms	2,554ms	p=0.298 n=6
Req 2 - geterr	6,016ms (± 0.58%)	6,025ms (± 0.78%)	~	5,978ms	6,107ms	p=1.000 n=6
Req 3 - references	352ms (± 0.63%)	353ms (± 0.74%)	~	349ms	357ms	p=0.739 n=6
Req 4 - navto	287ms (± 1.73%)	285ms (± 1.69%)	~	280ms	293ms	p=0.807 n=6
Req 5 - completionInfo count	1,356 (± 0.00%)	1,356 (± 0.00%)	~	1,356	1,356	p=1.000 n=6
Req 5 - completionInfo	90ms (± 5.22%)	89ms (± 5.56%)	~	80ms	92ms	p=0.865 n=6
CompilerTSServer - node (v16.17.1, x64)
Req 1 - updateOpen	2,661ms (± 1.15%)	2,682ms (± 0.89%)	~	2,644ms	2,713ms	p=0.199 n=6
Req 2 - geterr	4,620ms (± 0.51%)	4,631ms (± 0.38%)	~	4,615ms	4,654ms	p=0.470 n=6
Req 3 - references	358ms (± 0.51%)	360ms (± 0.49%)	~	359ms	363ms	p=0.088 n=6
Req 4 - navto	281ms (± 0.84%)	282ms (± 1.04%)	~	278ms	284ms	p=0.456 n=6
Req 5 - completionInfo count	1,518 (± 0.00%)	1,518 (± 0.00%)	~	1,518	1,518	p=1.000 n=6
Req 5 - completionInfo	68ms (± 1.24%)	68ms (± 1.72%)	~	66ms	69ms	p=0.555 n=6
xstateTSServer - node (v16.17.1, x64)
Req 1 - updateOpen	3,176ms (± 0.28%)	3,182ms (± 0.32%)	~	3,172ms	3,197ms	p=0.378 n=6
Req 2 - geterr	1,745ms (± 0.86%)	1,749ms (± 0.79%)	~	1,737ms	1,770ms	p=0.748 n=6
Req 3 - references	120ms (± 1.23%)	120ms (± 1.39%)	~	118ms	123ms	p=0.934 n=6
Req 4 - navto	342ms (± 1.04%)	341ms (± 0.34%)	~	339ms	342ms	p=0.868 n=6
Req 5 - completionInfo count	2,862 (± 0.00%)	2,862 (± 0.00%)	~	2,862	2,862	p=1.000 n=6
Req 5 - completionInfo	390ms (± 0.78%)	394ms (± 0.89%)	~	389ms	398ms	p=0.106 n=6

System

Machine Name	ts-ci-ubuntu
Platform	linux 5.4.0-135-generic
Architecture	x64
Available Memory	16 GB
Available Memory	15 GB
CPUs	4 × Intel(R) Core(TM) i7-4770 CPU @ 3.40GHz

Hosts

• node (v18.10.0, x64)
• node (v16.17.1, x64)
• node (v14.21.3, x64)

Scenarios

• Compiler-UnionsTSServer - node (v18.10.0, x64)
• Compiler-UnionsTSServer - node (v16.17.1, x64)
• Compiler-UnionsTSServer - node (v14.21.3, x64)
• CompilerTSServer - node (v18.10.0, x64)
• CompilerTSServer - node (v16.17.1, x64)
• CompilerTSServer - node (v14.21.3, x64)
• xstateTSServer - node (v18.10.0, x64)
• xstateTSServer - node (v16.17.1, x64)
• xstateTSServer - node (v14.21.3, x64)

Benchmark	Name	Iterations
Current	53489	6
Baseline	main	6

Startup

Comparison Report - main..53489

Metric	main	53489	Delta	Best	Worst	p-value
tsc-startup - node (v16.17.1, x64)
Execution time	141.84ms (± 0.16%)	142.14ms (± 0.20%)	+0.29ms (+ 0.21%)	141.48ms	147.46ms	p=0.000 n=600
tsserver-startup - node (v16.17.1, x64)
Execution time	220.14ms (± 0.16%)	220.89ms (± 0.19%)	+0.75ms (+ 0.34%)	219.95ms	230.61ms	p=0.000 n=600
tsserverlibrary-startup - node (v16.17.1, x64)
Execution time	221.64ms (± 0.16%)	222.09ms (± 0.16%)	+0.45ms (+ 0.20%)	221.29ms	228.00ms	p=0.000 n=600
typescript-startup - node (v16.17.1, x64)
Execution time	203.43ms (± 0.15%)	203.86ms (± 0.16%)	+0.43ms (+ 0.21%)	203.10ms	209.16ms	p=0.000 n=600

System

Machine Name	ts-ci-ubuntu
Platform	linux 5.4.0-135-generic
Architecture	x64
Available Memory	16 GB
Available Memory	15 GB
CPUs	4 × Intel(R) Core(TM) i7-4770 CPU @ 3.40GHz

Hosts

• node (v16.17.1, x64)

Scenarios

• tsc-startup - node (v16.17.1, x64)
• tsserver-startup - node (v16.17.1, x64)
• tsserverlibrary-startup - node (v16.17.1, x64)
• typescript-startup - node (v16.17.1, x64)

Benchmark	Name	Iterations
Current	53489	6
Baseline	main	6

Developer Information:

Download Benchmark

[TypeScript Bot (typescript-bot)]

Hey Daniel Rosenwasser (@DanielRosenwasser), the results of running the DT tests are ready.
Everything looks the same!
You can check the log here.

[TypeScript Bot (typescript-bot)]

Daniel Rosenwasser (@DanielRosenwasser) Here are the results of running the top-repos suite comparing main and refs/pull/53489/merge:

Everything looks good!

[Alex Ryan (ialexryan)]

Hurray! Thank you so much Wesley Wigham (@weswigham) 🎉 🙇🏻

[Georgii Dolzhykov (thorn0)]

Seems to fix #42646

[Craig P Hicks (craigphicks)]

I'm not sure what the proposed alternative is. If you're writing filter, you're probably writing arr.filter(x => expr), and we can't iteratively assign a type to x -- it needs to be a single type, ideally A | B.

For filter (and even if only for filter), I’d expect the type to be something like:

// Assuming the array is `A[] | B[]`(predicate: (item: A|B,index: number,array: A[]|B[])=>boolean)=>A[]|B[]

That functional definition of filter is not correct, it should be union of function definitions, one for each component type A and B. Otherwise a valid predicate like (item: A, index: number, array: A[]) will fail, and in fact in 5.2.2 it is failing - see #55777.

[Eric Ferreira (ericbf)]

I'm not sure what the proposed alternative is. If you're writing filter, you're probably writing arr.filter(x => expr), and we can't iteratively assign a type to x -- it needs to be a single type, ideally A | B.

For filter (and even if only for filter), I’d expect the type to be something like:

// Assuming the array is `A[] | B[]`(predicate: (item: A|B,index: number,array: A[]|B[])=>boolean)=>A[]|B[]

That functional definition of filter is not correct, it should be union of function definitions, one for each component type A and B. Otherwise a valid predicate like (item: A, index: number, array: A[]) will fail, and in fact in 5.2.2 it is failing - see #55777.

The way I see it, that value predicate should fail. There is no guarantee from a type system perspective that item is an A, so a predicate of (item: A...) isn’t compatible. That was why I suggested at least the proper return type (there is no situation under which filter would ever turn an A[] into an (A | B)[]).

In the linked issue, however, you have don’t just use a predicate of that single type ((item: A, index: number, array: A[]), which should and would fail by itself), but an overloaded function predicate, which is a different story.

BTW, usually it’s not ideal to start competing conversations in different issues, so let’s carry this on in the linked issue completely?