Improve logic that chooses co- vs. contra-variant inferences

[Anders Hejlsberg (ahejlsberg)]

Fixes#52111.

[Jake Bailey (jakebailey)]

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

[TypeScript Bot (typescript-bot)]

Heya Jake Bailey (@jakebailey), I've started to run the tarball bundle task on this PR at 26902df. You can monitor the build here.

[TypeScript Bot (typescript-bot)]

Heya Jake Bailey (@jakebailey), I've started to run the parallelized Definitely Typed test suite on this PR at 26902df. You can monitor the build here.

[TypeScript Bot (typescript-bot)]

Heya Jake Bailey (@jakebailey), I've started to run the extended test suite on this PR at 26902df. You can monitor the build here.

[TypeScript Bot (typescript-bot)]

Heya Jake Bailey (@jakebailey), I've started to run the diff-based user code test suite on this PR at 26902df. You can monitor the build here.

Update: The results are in!

[TypeScript Bot (typescript-bot)]

Heya Jake Bailey (@jakebailey), I've started to run the perf test suite on this PR at 26902df. You can monitor the build here.

Update: The results are in!

[TypeScript Bot (typescript-bot)]

Heya Jake Bailey (@jakebailey), I've started to run the diff-based top-repos suite on this PR at 26902df. You can monitor the build here.

Update: The results are in!

[TypeScript Bot (typescript-bot)]

Hey Jake Bailey (@jakebailey), 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/141820/artifacts?artifactName=tgz&fileId=571630FA0136B72F65125DEE199C24B9DB867FD2DFDC575B2F67317C7ED5F5C102&fileName=/typescript-5.0.0-insiders.20230106.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@5.0.0-pr-52123-7".;

[Jake Bailey (jakebailey)]

I can confirm that this fixes all of my cast/assert issues on the SFT branch. Wonderful!

[TypeScript Bot (typescript-bot)]

Jake Bailey (@jakebailey) Here are the results of running the user test suite comparing main and refs/pull/52123/merge:

Everything looks good!

[TypeScript Bot (typescript-bot)]

Heya Jake Bailey (@jakebailey), 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 (typescript-bot)]

Jake Bailey (@jakebailey) Here are the results of running the top-repos suite comparing main and refs/pull/52123/merge:

Everything looks good!

[TypeScript Bot (typescript-bot)]

Jake Bailey (@jakebailey)
The results of the perf run you requested are in!

Here they are:

Compiler

Comparison Report - main..52123

Metric	main	52123	Delta	Best	Worst
Angular - node (v18.10.0, x64)
Memory used	372,656k (± 0.01%)	372,647k (± 0.01%)	-9k (- 0.00%)	372,574k	372,722k
Parse Time	3.96s (± 0.66%)	3.95s (± 0.82%)	-0.01s (- 0.17%)	3.91s	3.99s
Bind Time	1.20s (± 1.12%)	1.20s (± 1.39%)	+0.00s (+ 0.12%)	1.18s	1.22s
Check Time	8.58s (± 0.52%)	8.61s (± 0.50%)	+0.03s (+ 0.39%)	8.54s	8.66s
Emit Time	7.55s (± 0.73%)	7.53s (± 1.05%)	-0.02s (- 0.30%)	7.46s	7.68s
Total Time	21.29s (± 0.47%)	21.30s (± 0.34%)	+0.01s (+ 0.03%)	21.20s	21.37s
Compiler-Unions - node (v18.10.0, x64)
Memory used	199,315k (± 1.16%)	199,326k (± 1.20%)	+11k (+ 0.01%)	198,311k	204,208k
Parse Time	1.64s (± 0.81%)	1.65s (± 1.09%)	+0.01s (+ 0.81%)	1.62s	1.67s
Bind Time	0.79s (± 0.70%)	0.79s (± 0.66%)	-0.00s (- 0.21%)	0.79s	0.80s
Check Time	9.47s (± 0.43%)	9.51s (± 0.41%)	+0.05s (+ 0.49%)	9.44s	9.56s
Emit Time	2.75s (± 1.00%)	2.76s (± 1.06%)	+0.01s (+ 0.55%)	2.72s	2.80s
Total Time	14.64s (± 0.34%)	14.71s (± 0.31%)	+0.07s (+ 0.49%)	14.64s	14.78s
Monaco - node (v18.10.0, x64)
Memory used	354,086k (± 0.02%)	354,085k (± 0.01%)	-1k (- 0.00%)	354,039k	354,133k
Parse Time	2.97s (± 1.00%)	2.96s (± 0.79%)	-0.02s (- 0.57%)	2.92s	2.99s
Bind Time	1.05s (± 0.86%)	1.04s (± 1.37%)	-0.01s (- 0.54%)	1.03s	1.07s
Check Time	7.22s (± 0.38%)	7.23s (± 0.40%)	+0.01s (+ 0.12%)	7.19s	7.27s
Emit Time	4.27s (± 1.06%)	4.23s (± 0.22%)	-0.04s (- 1.04%)	4.21s	4.24s
Total Time	15.51s (± 0.45%)	15.46s (± 0.20%)	-0.06s (- 0.36%)	15.41s	15.50s
TFS - node (v18.10.0, x64)
Memory used	310,033k (± 0.00%)	310,021k (± 0.01%)	-13k (- 0.00%)	309,992k	310,042k
Parse Time	2.26s (± 0.93%)	2.26s (± 1.21%)	+0.00s (+ 0.00%)	2.22s	2.30s
Bind Time	1.16s (± 0.74%)	1.16s (± 0.69%)	+0.00s (+ 0.14%)	1.15s	1.17s
Check Time	6.80s (± 0.49%)	6.79s (± 0.49%)	-0.01s (- 0.12%)	6.75s	6.85s
Emit Time	3.92s (± 0.73%)	3.90s (± 0.36%)	-0.01s (- 0.38%)	3.88s	3.91s
Total Time	14.13s (± 0.32%)	14.10s (± 0.32%)	-0.02s (- 0.15%)	14.06s	14.18s
material-ui - node (v18.10.0, x64)
Memory used	485,238k (± 0.01%)	485,221k (± 0.01%)	-17k (- 0.00%)	485,180k	485,300k
Parse Time	3.52s (± 0.32%)	3.53s (± 0.59%)	+0.01s (+ 0.41%)	3.50s	3.56s
Bind Time	0.96s (± 0.93%)	0.97s (± 0.96%)	+0.00s (+ 0.45%)	0.95s	0.97s
Check Time	16.91s (± 0.26%)	16.93s (± 0.67%)	+0.02s (+ 0.14%)	16.76s	17.07s
Emit Time	0.00s (± 0.00%)	0.00s (± 0.00%)	0.00s ( NaN%)	0.00s	0.00s
Total Time	21.38s (± 0.21%)	21.43s (± 0.57%)	+0.05s (+ 0.21%)	21.27s	21.59s
xstate - node (v18.10.0, x64)
Memory used	570,392k (± 0.02%)	570,241k (± 0.03%)	-151k (- 0.03%)	570,089k	570,489k
Parse Time	4.41s (± 0.52%)	4.43s (± 0.58%)	+0.02s (+ 0.39%)	4.40s	4.47s
Bind Time	1.69s (± 1.61%)	1.71s (± 0.54%)	+0.02s (+ 0.94%)	1.70s	1.72s
Check Time	2.60s (± 0.54%)	2.60s (± 0.86%)	-0.01s (- 0.20%)	2.57s	2.63s
Emit Time	0.08s (± 0.17%)	0.08s (± 0.20%)	-0.00s (- 0.13%)	0.08s	0.08s
Total Time	8.80s (± 0.41%)	8.82s (± 0.28%)	+0.02s (+ 0.24%)	8.79s	8.86s
Angular - node (v16.17.1, x64)
Memory used	372,007k (± 0.01%)	371,978k (± 0.01%)	-29k (- 0.01%)	371,924k	372,021k
Parse Time	4.13s (± 0.32%)	4.15s (± 0.87%)	+0.03s (+ 0.63%)	4.12s	4.21s
Bind Time	1.27s (± 0.55%)	1.27s (± 0.96%)	+0.00s (+ 0.10%)	1.25s	1.28s
Check Time	9.31s (± 0.52%)	9.29s (± 0.40%)	-0.02s (- 0.22%)	9.23s	9.34s
Emit Time	8.03s (± 0.55%)	8.01s (± 0.28%)	-0.02s (- 0.25%)	7.99s	8.04s
Total Time	22.74s (± 0.12%)	22.72s (± 0.26%)	-0.01s (- 0.05%)	22.65s	22.81s
Compiler-Unions - node (v16.17.1, x64)
Memory used	200,590k (± 0.64%)	201,106k (± 0.86%)	+516k (+ 0.26%)	199,946k	203,457k
Parse Time	1.81s (± 0.57%)	1.81s (± 0.58%)	-0.00s (- 0.09%)	1.80s	1.83s
Bind Time	0.84s (± 1.22%)	0.84s (± 1.22%)	-0.00s (- 0.00%)	0.83s	0.86s
Check Time	10.12s (± 1.29%)	10.04s (± 0.58%)	-0.08s (- 0.82%)	9.95s	10.10s
Emit Time	2.99s (± 1.21%)	2.98s (± 1.11%)	-0.01s (- 0.22%)	2.93s	3.03s
Total Time	15.76s (± 1.06%)	15.67s (± 0.51%)	-0.09s (- 0.60%)	15.53s	15.74s
Monaco - node (v16.17.1, x64)
Memory used	353,413k (± 0.01%)	353,393k (± 0.01%)	-20k (- 0.01%)	353,356k	353,435k
Parse Time	3.17s (± 0.54%)	3.17s (± 0.55%)	+0.00s (+ 0.04%)	3.14s	3.19s
Bind Time	1.13s (± 1.34%)	1.13s (± 1.24%)	+0.00s (+ 0.38%)	1.12s	1.15s
Check Time	7.85s (± 0.45%)	7.86s (± 0.62%)	+0.01s (+ 0.12%)	7.77s	7.92s
Emit Time	4.49s (± 0.49%)	4.48s (± 0.41%)	-0.01s (- 0.18%)	4.47s	4.52s
Total Time	16.63s (± 0.18%)	16.64s (± 0.28%)	+0.01s (+ 0.08%)	16.58s	16.70s
TFS - node (v16.17.1, x64)
Memory used	309,368k (± 0.00%)	309,375k (± 0.01%)	+7k (+ 0.00%)	309,354k	309,401k
Parse Time	2.60s (± 1.08%)	2.60s (± 1.39%)	-0.01s (- 0.22%)	2.55s	2.65s
Bind Time	1.07s (± 2.18%)	1.07s (± 1.57%)	-0.00s (- 0.06%)	1.05s	1.10s
Check Time	7.39s (± 0.50%)	7.41s (± 0.38%)	+0.01s (+ 0.19%)	7.37s	7.45s
Emit Time	4.19s (± 0.49%)	4.22s (± 0.44%)	+0.02s (+ 0.53%)	4.19s	4.24s
Total Time	15.26s (± 0.33%)	15.29s (± 0.38%)	+0.03s (+ 0.20%)	15.24s	15.39s
material-ui - node (v16.17.1, x64)
Memory used	484,506k (± 0.00%)	484,506k (± 0.00%)	+1k (+ 0.00%)	484,486k	484,531k
Parse Time	3.67s (± 0.35%)	3.67s (± 0.31%)	+0.00s (+ 0.00%)	3.67s	3.70s
Bind Time	1.01s (± 0.47%)	1.01s (± 0.38%)	+0.00s (+ 0.36%)	1.01s	1.02s
Check Time	17.85s (± 0.25%)	17.83s (± 0.32%)	-0.02s (- 0.12%)	17.77s	17.93s
Emit Time	0.00s (± 0.00%)	0.00s (± 0.00%)	0.00s ( NaN%)	0.00s	0.00s
Total Time	22.54s (± 0.22%)	22.52s (± 0.26%)	-0.01s (- 0.06%)	22.46s	22.63s
xstate - node (v16.17.1, x64)
Memory used	567,851k (± 0.02%)	567,821k (± 0.02%)	-30k (- 0.01%)	567,705k	567,932k
Parse Time	4.75s (± 0.34%)	4.76s (± 0.24%)	+0.02s (+ 0.34%)	4.74s	4.77s
Bind Time	1.65s (± 0.61%)	1.66s (± 0.46%)	+0.01s (+ 0.54%)	1.64s	1.67s
Check Time	2.83s (± 0.51%)	2.83s (± 0.60%)	+0.00s (+ 0.01%)	2.80s	2.85s
Emit Time	0.09s (± 0.16%)	0.09s (± 0.16%)	+0.00s (+ 0.13%)	0.09s	0.09s
Total Time	9.31s (± 0.30%)	9.34s (± 0.21%)	+0.03s (+ 0.33%)	9.31s	9.36s
Angular - node (v14.15.1, x64)
Memory used	365,663k (± 0.00%)	365,647k (± 0.00%)	-16k (- 0.00%)	365,637k	365,654k
Parse Time	4.15s (± 0.91%)	4.15s (± 0.61%)	+0.00s (+ 0.07%)	4.12s	4.19s
Bind Time	1.30s (± 0.65%)	1.30s (± 0.60%)	+0.00s (+ 0.16%)	1.30s	1.32s
Check Time	9.68s (± 0.51%)	9.68s (± 0.51%)	-0.01s (- 0.05%)	9.62s	9.76s
Emit Time	8.20s (± 0.55%)	8.22s (± 0.85%)	+0.02s (+ 0.24%)	8.14s	8.30s
Total Time	23.34s (± 0.30%)	23.36s (± 0.48%)	+0.01s (+ 0.06%)	23.23s	23.48s
Compiler-Unions - node (v14.15.1, x64)
Memory used	195,146k (± 0.02%)	195,158k (± 0.02%)	+13k (+ 0.01%)	195,120k	195,215k
Parse Time	1.85s (± 0.37%)	1.84s (± 0.54%)	-0.00s (- 0.22%)	1.83s	1.86s
Bind Time	0.87s (± 0.52%)	0.87s (± 0.63%)	-0.00s (- 0.32%)	0.87s	0.88s
Check Time	10.15s (± 0.84%)	10.15s (± 0.52%)	-0.00s (- 0.04%)	10.09s	10.22s
Emit Time	3.13s (± 0.71%)	3.13s (± 0.93%)	+0.00s (+ 0.13%)	3.08s	3.16s
Total Time	16.00s (± 0.41%)	16.00s (± 0.39%)	-0.01s (- 0.04%)	15.93s	16.08s
Monaco - node (v14.15.1, x64)
Memory used	348,245k (± 0.01%)	348,242k (± 0.01%)	-3k (- 0.00%)	348,189k	348,281k
Parse Time	3.22s (± 1.14%)	3.27s (± 0.51%)	+0.04s (+ 1.30%)	3.24s	3.28s
Bind Time	1.12s (± 0.59%)	1.12s (± 0.39%)	-0.00s (- 0.08%)	1.12s	1.13s
Check Time	8.15s (± 0.23%)	8.16s (± 0.55%)	+0.01s (+ 0.11%)	8.11s	8.22s
Emit Time	4.70s (± 0.67%)	4.70s (± 0.67%)	-0.00s (- 0.04%)	4.66s	4.75s
Total Time	17.19s (± 0.41%)	17.25s (± 0.38%)	+0.05s (+ 0.32%)	17.19s	17.34s
TFS - node (v14.15.1, x64)
Memory used	304,287k (± 0.01%)	304,291k (± 0.00%)	+4k (+ 0.00%)	304,275k	304,309k
Parse Time	2.72s (± 0.30%)	2.72s (± 1.14%)	-0.00s (- 0.05%)	2.67s	2.75s
Bind Time	1.08s (± 0.55%)	1.08s (± 0.71%)	+0.00s (+ 0.37%)	1.07s	1.09s
Check Time	7.69s (± 0.45%)	7.71s (± 0.67%)	+0.03s (+ 0.37%)	7.62s	7.77s
Emit Time	4.55s (± 0.94%)	4.58s (± 0.75%)	+0.02s (+ 0.50%)	4.52s	4.62s
Total Time	16.04s (± 0.39%)	16.09s (± 0.17%)	+0.05s (+ 0.30%)	16.04s	16.13s
material-ui - node (v14.15.1, x64)
Memory used	479,942k (± 0.01%)	479,941k (± 0.00%)	-1k (- 0.00%)	479,911k	479,967k
Parse Time	3.89s (± 0.80%)	3.89s (± 0.60%)	+0.01s (+ 0.22%)	3.87s	3.92s
Bind Time	1.04s (± 0.74%)	1.05s (± 0.83%)	+0.00s (+ 0.31%)	1.03s	1.06s
Check Time	18.99s (± 0.58%)	18.83s (± 0.77%)	-0.15s (- 0.81%)	18.62s	18.99s
Emit Time	0.00s (± 0.00%)	0.00s (± 0.00%)	0.00s ( NaN%)	0.00s	0.00s
Total Time	23.92s (± 0.41%)	23.78s (± 0.73%)	-0.15s (- 0.61%)	23.51s	23.98s
xstate - node (v14.15.1, x64)
Memory used	556,177k (± 0.00%)	556,181k (± 0.01%)	+4k (+ 0.00%)	556,121k	556,221k
Parse Time	5.14s (± 0.72%)	5.11s (± 0.60%)	-0.03s (- 0.59%)	5.06s	5.14s
Bind Time	1.58s (± 0.77%)	1.59s (± 0.91%)	+0.01s (+ 0.54%)	1.57s	1.61s
Check Time	2.99s (± 0.55%)	2.99s (± 0.53%)	+0.00s (+ 0.13%)	2.97s	3.02s
Emit Time	0.10s (± 0.08%)	0.10s (± 0.08%)	-0.00s (- 0.20%)	0.10s	0.10s
Total Time	9.81s (± 0.47%)	9.79s (± 0.49%)	-0.02s (- 0.17%)	9.71s	9.85s

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	52123	6
Baseline	main	6

TSServer

Comparison Report - main..52123

Metric	main	52123	Delta	Best	Worst
Compiler-UnionsTSServer - node (v18.10.0, x64)
Req 1 - updateOpen	2,540ms (± 1.47%)	2,553ms (± 2.14%)	+12ms (+ 0.49%)	2,478ms	2,632ms
Req 2 - geterr	5,368ms (± 0.91%)	5,384ms (± 1.60%)	+17ms (+ 0.31%)	5,293ms	5,542ms
Req 3 - references	369ms (± 0.64%)	366ms (± 2.16%)	-3ms (- 0.78%)	354ms	371ms
Req 4 - navto	282ms (± 2.49%)	288ms (± 3.70%)	+6ms (+ 2.00%)	276ms	300ms
Req 5 - completionInfo count	1,356 (± 0.00%)	1,356 (± 0.00%)	0 ( 0.00%)	1,356	1,356
Req 5 - completionInfo	300ms (± 3.08%)	265ms (±33.49%)	🟩-35ms (-11.81%)	84ms	310ms
CompilerTSServer - node (v18.10.0, x64)
Req 1 - updateOpen	2,728ms (± 1.41%)	2,766ms (± 0.48%)	+38ms (+ 1.41%)	2,748ms	2,784ms
Req 2 - geterr	3,960ms (± 0.67%)	3,968ms (± 0.66%)	+8ms (+ 0.21%)	3,940ms	4,014ms
Req 3 - references	361ms (± 1.20%)	361ms (± 0.71%)	+1ms (+ 0.15%)	358ms	364ms
Req 4 - navto	289ms (± 1.06%)	290ms (± 1.37%)	+1ms (+ 0.18%)	284ms	296ms
Req 5 - completionInfo count	1,518 (± 0.00%)	1,518 (± 0.00%)	0 ( 0.00%)	1,518	1,518
Req 5 - completionInfo	68ms (± 4.18%)	69ms (± 4.39%)	+0ms (+ 0.29%)	65ms	73ms
xstateTSServer - node (v18.10.0, x64)
Req 1 - updateOpen	3,391ms (± 0.69%)	3,378ms (± 0.70%)	-12ms (- 0.36%)	3,339ms	3,410ms
Req 2 - geterr	1,550ms (± 1.16%)	1,540ms (± 0.81%)	-10ms (- 0.64%)	1,529ms	1,559ms
Req 3 - references	109ms (± 1.54%)	108ms (± 1.75%)	-1ms (- 1.28%)	105ms	110ms
Req 4 - navto	359ms (± 1.20%)	358ms (± 1.18%)	-1ms (- 0.26%)	354ms	364ms
Req 5 - completionInfo count	3,154 (± 0.00%)	3,154 (± 0.00%)	0 ( 0.00%)	3,154	3,154
Req 5 - completionInfo	434ms (± 1.90%)	438ms (± 0.95%)	+4ms (+ 0.86%)	433ms	445ms
Compiler-UnionsTSServer - node (v16.17.1, x64)
Req 1 - updateOpen	2,778ms (± 0.29%)	2,753ms (± 0.82%)	-25ms (- 0.89%)	2,724ms	2,780ms
Req 2 - geterr	5,775ms (± 1.67%)	5,884ms (± 1.74%)	+110ms (+ 1.90%)	5,690ms	5,976ms
Req 3 - references	370ms (± 1.69%)	361ms (± 0.94%)	-9ms (- 2.52%)	356ms	366ms
Req 4 - navto	281ms (± 1.46%)	283ms (± 1.83%)	+2ms (+ 0.57%)	278ms	291ms
Req 5 - completionInfo count	1,356 (± 0.00%)	1,356 (± 0.00%)	0 ( 0.00%)	1,356	1,356
Req 5 - completionInfo	282ms (±33.59%)	130ms (±71.13%)	🟩-151ms (-53.75%)	90ms	320ms
CompilerTSServer - node (v16.17.1, x64)
Req 1 - updateOpen	2,911ms (± 0.66%)	2,924ms (± 0.49%)	+13ms (+ 0.43%)	2,906ms	2,946ms
Req 2 - geterr	4,312ms (± 0.35%)	4,291ms (± 0.52%)	-21ms (- 0.48%)	4,262ms	4,320ms
Req 3 - references	378ms (± 0.48%)	377ms (± 0.65%)	-1ms (- 0.39%)	373ms	379ms
Req 4 - navto	301ms (± 0.55%)	302ms (± 1.42%)	+1ms (+ 0.40%)	299ms	310ms
Req 5 - completionInfo count	1,518 (± 0.00%)	1,518 (± 0.00%)	0 ( 0.00%)	1,518	1,518
Req 5 - completionInfo	274ms (±35.85%)	314ms (± 0.84%)	+40ms (+14.47%)	311ms	318ms
xstateTSServer - node (v16.17.1, x64)
Req 1 - updateOpen	3,768ms (± 0.21%)	3,755ms (± 0.61%)	-13ms (- 0.35%)	3,726ms	3,796ms
Req 2 - geterr	1,467ms (± 1.33%)	1,452ms (± 0.90%)	-16ms (- 1.06%)	1,432ms	1,469ms
Req 3 - references	112ms (± 3.57%)	112ms (± 3.66%)	+0ms (+ 0.02%)	108ms	118ms
Req 4 - navto	344ms (± 1.97%)	346ms (± 3.02%)	+3ms (+ 0.77%)	336ms	363ms
Req 5 - completionInfo count	3,154 (± 0.00%)	3,154 (± 0.00%)	0 ( 0.00%)	3,154	3,154
Req 5 - completionInfo	463ms (± 1.89%)	462ms (± 1.52%)	-0ms (- 0.10%)	456ms	472ms
Compiler-UnionsTSServer - node (v14.15.1, x64)
Req 1 - updateOpen	2,880ms (± 0.28%)	2,890ms (± 0.72%)	+11ms (+ 0.37%)	2,866ms	2,919ms
Req 2 - geterr	6,112ms (± 0.75%)	6,135ms (± 0.93%)	+22ms (+ 0.37%)	6,068ms	6,214ms
Req 3 - references	383ms (± 1.11%)	384ms (± 1.27%)	+2ms (+ 0.44%)	379ms	393ms
Req 4 - navto	290ms (± 1.05%)	292ms (± 0.67%)	+2ms (+ 0.73%)	290ms	295ms
Req 5 - completionInfo count	1,356 (± 0.00%)	1,356 (± 0.00%)	0 ( 0.00%)	1,356	1,356
Req 5 - completionInfo	163ms (±73.80%)	323ms (± 1.05%)	🔻+160ms (+98.03%)	320ms	328ms
CompilerTSServer - node (v14.15.1, x64)
Req 1 - updateOpen	3,042ms (± 1.00%)	3,019ms (± 0.73%)	-23ms (- 0.76%)	2,993ms	3,054ms
Req 2 - geterr	4,583ms (± 0.70%)	4,542ms (± 0.89%)	-41ms (- 0.90%)	4,485ms	4,586ms
Req 3 - references	404ms (± 0.97%)	403ms (± 0.82%)	-1ms (- 0.21%)	399ms	408ms
Req 4 - navto	308ms (± 1.19%)	306ms (± 0.66%)	-2ms (- 0.79%)	304ms	308ms
Req 5 - completionInfo count	1,518 (± 0.00%)	1,518 (± 0.00%)	0 ( 0.00%)	1,518	1,518
Req 5 - completionInfo	86ms (±10.30%)	83ms (± 6.93%)	-2ms (- 2.86%)	76ms	91ms
xstateTSServer - node (v14.15.1, x64)
Req 1 - updateOpen	3,865ms (± 0.89%)	3,876ms (± 0.51%)	+11ms (+ 0.29%)	3,841ms	3,901ms
Req 2 - geterr	1,458ms (± 1.05%)	1,469ms (± 1.14%)	+10ms (+ 0.71%)	1,452ms	1,495ms
Req 3 - references	131ms (± 1.74%)	134ms (± 1.26%)	+2ms (+ 1.67%)	131ms	135ms
Req 4 - navto	391ms (± 1.07%)	398ms (± 1.33%)	+7ms (+ 1.77%)	392ms	406ms
Req 5 - completionInfo count	3,154 (± 0.00%)	3,154 (± 0.00%)	0 ( 0.00%)	3,154	3,154
Req 5 - completionInfo	501ms (± 1.53%)	496ms (± 1.09%)	-5ms (- 1.02%)	490ms	503ms

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	52123	6
Baseline	main	6

Startup

Comparison Report - main..52123

Metric	main	52123	Delta	Best	Worst
tsc-startup - node (v16.17.1, x64)
Execution time	139.22ms (± 0.24%)	139.04ms (± 0.19%)	-0.17ms (- 0.13%)	137.99ms	142.38ms
tsserver-startup - node (v16.17.1, x64)
Execution time	229.56ms (± 0.18%)	231.08ms (± 0.17%)	+1.52ms (+ 0.66%)	229.64ms	234.89ms
tsserverlibrary-startup - node (v16.17.1, x64)
Execution time	232.52ms (± 0.17%)	233.46ms (± 0.19%)	+0.93ms (+ 0.40%)	231.83ms	240.22ms
typescript-startup - node (v16.17.1, x64)
Execution time	213.99ms (± 0.21%)	214.98ms (± 0.16%)	+0.99ms (+ 0.46%)	213.59ms	220.34ms

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	52123	6
Baseline	main	6

Developer Information:

Download Benchmark

[Jake Bailey (jakebailey)]

Another example that I didn't realize was affected is this:

interfaceA{a: string;}interfaceBextendsA{b: string;}interfaceCextendsA{c: string}

Then:

declarefunctionisC(x: A): x is C;declarefunctionevery<T,UextendsT>(array: readonlyT[],callback: (element: T,index: number)=>element is U): array is readonlyU[];declarefunctionevery<T,UextendsT>(array: readonlyT[]|undefined,callback: (element: T,index: number)=>element is U): array is readonlyU[]|undefined;declarefunctionevery<T>(array: readonlyT[]|undefined,callback: (element: T,index: number)=>boolean): boolean;functionfoo(arr: readonlyB[]|readonlyC[]|undefined){if(every(arr,isC)){arr;}}

In TS 4.9, this code errors because it picks every<B, B>, but now, it picks every<A, C>, and we get arr narrowed to readonly C[]. This comes up quite a bit on the SFT branch.

(I may send a PR for this test case too.)

[Jake Bailey (jakebailey)]

I have another followup case that turned out to not be fixed (I also didn't catch it in the SFT branch in the same way as the above fixed case); I'll file a new issue.