Fix for relating covered discriminants in unions

[Ron Buckton (rbuckton)]

In #30779 we added the ability to relate a source type to a target when the target is a discriminated union and the source is covered by the target. This did not work when the target was a union of tuple types as the relationship check would fail when comparing the synthesized index types for each tuple in indexTypesRelatedTo. This was further complicated by the fact that the new variadic tuple type logic added to propertiesRelatedTo fails to exclude relationship checks for non-variable elements whose indices are included in the excludedProperties map.

This PR does two things to address these issues:

• Adds discriminant exclusion into the tuple-specific branch in propertiesRelatedTo so that it aligns with the existing, non-tuple-specific logic.
• Skips the indexTypesRelatedTo check when both the source type and the target type are tuples, as the index type check should be sufficiently covered by the tuple-specific branch in propertiesRelatedTo.

Alternatively, rather than skipping the indexTypesRelatedTo check, we could synthesize a copy of the source and target tuple types with the excluded discriminants erased to never so that they are excluded from the index type. That would result in the allocation of types purely to accommodate indexTypesRelatedTo, which would then be subsequently discarded. This seems like an unnecessary cost, as propertiesRelatedTo sufficiently covers the numeric index type case.

Fixes#39357
Fixes#34967

[Ron Buckton (rbuckton)]

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

[TypeScript Bot (typescript-bot)]

Heya Ron Buckton (@rbuckton), I've started to run the perf test suite on this PR at 8eba362. You can monitor the build here.

Update: The results are in!

[TypeScript Bot (typescript-bot)]

Heya Ron Buckton (@rbuckton), I've started to run the parallelized Definitely Typed test suite on this PR at 8eba362. You can monitor the build here.

[TypeScript Bot (typescript-bot)]

Heya Ron Buckton (@rbuckton), I've started to run the extended test suite on this PR at 8eba362. You can monitor the build here.

[TypeScript Bot (typescript-bot)]

Heya Ron Buckton (@rbuckton), I've started to run the parallelized community code test suite on this PR at 8eba362. You can monitor the build here.

[TypeScript Bot (typescript-bot)]

The user suite test run you requested has finished and failed. I've opened a PR with the baseline diff from master.

[TypeScript Bot (typescript-bot)]

Ron Buckton (@rbuckton)
The results of the perf run you requested are in!

Here they are:

Comparison Report - master..39393

Metric	master	39393	Delta	Best	Worst
Angular - node (v10.16.3, x64)
Memory used	344,003k (± 0.02%)	343,525k (± 0.03%)	-478k (- 0.14%)	343,310k	343,841k
Parse Time	2.00s (± 0.58%)	2.01s (± 0.67%)	+0.00s (+ 0.15%)	1.98s	2.03s
Bind Time	0.82s (± 0.41%)	0.82s (± 0.60%)	-0.00s (- 0.49%)	0.81s	0.83s
Check Time	4.72s (± 0.32%)	4.70s (± 0.51%)	-0.01s (- 0.30%)	4.65s	4.74s
Emit Time	5.17s (± 0.39%)	5.15s (± 0.70%)	-0.02s (- 0.39%)	5.10s	5.26s
Total Time	12.71s (± 0.24%)	12.68s (± 0.47%)	-0.04s (- 0.28%)	12.55s	12.86s
Monaco - node (v10.16.3, x64)
Memory used	339,106k (± 0.02%)	339,046k (± 0.02%)	-60k (- 0.02%)	338,950k	339,244k
Parse Time	1.58s (± 0.64%)	1.59s (± 0.50%)	+0.01s (+ 0.83%)	1.57s	1.61s
Bind Time	0.71s (± 0.63%)	0.71s (± 0.67%)	-0.01s (- 0.70%)	0.70s	0.72s
Check Time	4.86s (± 0.50%)	4.86s (± 0.56%)	+0.01s (+ 0.16%)	4.81s	4.92s
Emit Time	2.77s (± 0.66%)	2.74s (± 0.41%)	-0.03s (- 1.05%)	2.71s	2.76s
Total Time	9.91s (± 0.40%)	9.90s (± 0.39%)	-0.02s (- 0.15%)	9.81s	9.98s
TFS - node (v10.16.3, x64)
Memory used	301,981k (± 0.03%)	302,036k (± 0.03%)	+55k (+ 0.02%)	301,930k	302,266k
Parse Time	1.21s (± 0.75%)	1.21s (± 0.70%)	0.00s ( 0.00%)	1.19s	1.22s
Bind Time	0.66s (± 1.28%)	0.67s (± 1.12%)	+0.01s (+ 0.91%)	0.64s	0.68s
Check Time	4.40s (± 0.53%)	4.36s (± 0.52%)	-0.04s (- 0.84%)	4.32s	4.42s
Emit Time	2.88s (± 1.22%)	2.88s (± 0.78%)	+0.00s (+ 0.03%)	2.83s	2.94s
Total Time	9.14s (± 0.64%)	9.11s (± 0.36%)	-0.03s (- 0.32%)	9.03s	9.20s
material-ui - node (v10.16.3, x64)
Memory used	459,384k (± 0.01%)	459,141k (± 0.01%)	-244k (- 0.05%)	458,995k	459,263k
Parse Time	2.05s (± 0.52%)	2.04s (± 0.25%)	-0.00s (- 0.20%)	2.03s	2.05s
Bind Time	0.66s (± 1.28%)	0.65s (± 1.08%)	-0.01s (- 1.21%)	0.64s	0.67s
Check Time	12.80s (± 0.48%)	12.84s (± 0.80%)	+0.04s (+ 0.27%)	12.68s	13.16s
Emit Time	0.00s (± 0.00%)	0.00s (± 0.00%)	0.00s ( NaN%)	0.00s	0.00s
Total Time	15.50s (± 0.44%)	15.53s (± 0.67%)	+0.03s (+ 0.17%)	15.37s	15.87s
Angular - node (v12.1.0, x64)
Memory used	321,096k (± 0.03%)	320,726k (± 0.03%)	-370k (- 0.12%)	320,519k	320,983k
Parse Time	1.99s (± 0.68%)	1.98s (± 0.75%)	-0.01s (- 0.40%)	1.94s	2.00s
Bind Time	0.80s (± 0.85%)	0.80s (± 0.59%)	-0.00s (- 0.62%)	0.79s	0.81s
Check Time	4.60s (± 0.47%)	4.60s (± 0.49%)	-0.00s (- 0.04%)	4.55s	4.66s
Emit Time	5.34s (± 0.56%)	5.33s (± 0.34%)	-0.01s (- 0.13%)	5.30s	5.37s
Total Time	12.73s (± 0.37%)	12.71s (± 0.27%)	-0.02s (- 0.20%)	12.64s	12.79s
Monaco - node (v12.1.0, x64)
Memory used	321,518k (± 0.02%)	321,507k (± 0.02%)	-11k (- 0.00%)	321,422k	321,645k
Parse Time	1.55s (± 0.83%)	1.54s (± 0.44%)	-0.01s (- 0.58%)	1.54s	1.57s
Bind Time	0.69s (± 0.84%)	0.68s (± 0.70%)	-0.00s (- 0.58%)	0.67s	0.69s
Check Time	4.65s (± 0.54%)	4.63s (± 0.43%)	-0.01s (- 0.30%)	4.60s	4.69s
Emit Time	2.80s (± 0.61%)	2.80s (± 0.73%)	+0.00s (+ 0.11%)	2.75s	2.83s
Total Time	9.68s (± 0.38%)	9.66s (± 0.36%)	-0.02s (- 0.21%)	9.60s	9.74s
TFS - node (v12.1.0, x64)
Memory used	286,487k (± 0.02%)	286,475k (± 0.02%)	-11k (- 0.00%)	286,312k	286,583k
Parse Time	1.23s (± 0.61%)	1.24s (± 1.41%)	+0.01s (+ 0.90%)	1.21s	1.29s
Bind Time	0.64s (± 1.20%)	0.64s (± 1.14%)	+0.00s (+ 0.47%)	0.63s	0.66s
Check Time	4.26s (± 0.51%)	4.26s (± 0.64%)	-0.00s (- 0.07%)	4.17s	4.31s
Emit Time	2.91s (± 0.96%)	2.93s (± 0.74%)	+0.02s (+ 0.83%)	2.89s	2.99s
Total Time	9.04s (± 0.45%)	9.07s (± 0.46%)	+0.03s (+ 0.34%)	8.97s	9.17s
material-ui - node (v12.1.0, x64)
Memory used	437,699k (± 0.05%)	437,426k (± 0.05%)	-273k (- 0.06%)	436,516k	437,639k
Parse Time	2.01s (± 0.47%)	2.02s (± 0.49%)	+0.01s (+ 0.35%)	2.00s	2.04s
Bind Time	0.63s (± 1.18%)	0.63s (± 1.05%)	0.00s ( 0.00%)	0.62s	0.65s
Check Time	11.54s (± 0.86%)	11.57s (± 1.06%)	+0.03s (+ 0.24%)	11.35s	11.91s
Emit Time	0.00s (± 0.00%)	0.00s (± 0.00%)	0.00s ( NaN%)	0.00s	0.00s
Total Time	14.18s (± 0.70%)	14.22s (± 0.87%)	+0.04s (+ 0.25%)	13.98s	14.56s
Angular - node (v8.9.0, x64)
Memory used	340,422k (± 0.02%)	340,050k (± 0.02%)	-371k (- 0.11%)	339,923k	340,245k
Parse Time	2.54s (± 0.44%)	2.52s (± 0.27%)	-0.02s (- 0.71%)	2.50s	2.53s
Bind Time	0.85s (± 0.89%)	0.85s (± 0.79%)	-0.01s (- 0.94%)	0.83s	0.86s
Check Time	5.33s (± 0.55%)	5.35s (± 0.66%)	+0.02s (+ 0.36%)	5.29s	5.46s
Emit Time	5.98s (± 0.88%)	5.88s (± 1.67%)	-0.09s (- 1.56%)	5.67s	6.06s
Total Time	14.70s (± 0.30%)	14.60s (± 0.81%)	-0.10s (- 0.67%)	14.36s	14.80s
Monaco - node (v8.9.0, x64)
Memory used	340,467k (± 0.01%)	340,461k (± 0.01%)	-7k (- 0.00%)	340,406k	340,522k
Parse Time	1.87s (± 0.47%)	1.87s (± 0.66%)	-0.00s (- 0.16%)	1.85s	1.91s
Bind Time	0.88s (± 0.45%)	0.88s (± 0.45%)	0.00s ( 0.00%)	0.87s	0.89s
Check Time	5.36s (± 0.58%)	5.38s (± 0.60%)	+0.02s (+ 0.37%)	5.32s	5.46s
Emit Time	3.22s (± 0.41%)	3.22s (± 0.75%)	+0.00s (+ 0.12%)	3.19s	3.29s
Total Time	11.33s (± 0.43%)	11.35s (± 0.47%)	+0.02s (+ 0.16%)	11.26s	11.52s
TFS - node (v8.9.0, x64)
Memory used	303,763k (± 0.01%)	303,812k (± 0.02%)	+49k (+ 0.02%)	303,635k	303,956k
Parse Time	1.55s (± 0.92%)	1.55s (± 0.32%)	-0.00s (- 0.06%)	1.53s	1.55s
Bind Time	0.67s (± 0.67%)	0.67s (± 1.14%)	-0.00s (- 0.45%)	0.65s	0.68s
Check Time	4.99s (± 1.47%)	5.02s (± 1.64%)	+0.03s (+ 0.64%)	4.84s	5.16s
Emit Time	3.04s (± 3.30%)	3.03s (± 3.07%)	-0.01s (- 0.30%)	2.88s	3.20s
Total Time	10.24s (± 0.35%)	10.26s (± 0.53%)	+0.02s (+ 0.21%)	10.12s	10.37s
material-ui - node (v8.9.0, x64)
Memory used	463,609k (± 0.01%)	463,357k (± 0.01%)	-252k (- 0.05%)	463,264k	463,495k
Parse Time	2.39s (± 0.73%)	2.38s (± 0.22%)	-0.01s (- 0.42%)	2.37s	2.39s
Bind Time	0.78s (± 0.98%)	0.77s (± 0.88%)	-0.00s (- 0.26%)	0.76s	0.79s
Check Time	17.11s (± 1.10%)	17.23s (± 0.50%)	+0.12s (+ 0.70%)	17.07s	17.51s
Emit Time	0.00s (± 0.00%)	0.00s (± 0.00%)	0.00s ( NaN%)	0.00s	0.00s
Total Time	20.28s (± 0.99%)	20.38s (± 0.45%)	+0.11s (+ 0.54%)	20.22s	20.69s
Angular - node (v8.9.0, x86)
Memory used	195,298k (± 0.03%)	195,097k (± 0.02%)	-201k (- 0.10%)	194,989k	195,173k
Parse Time	2.46s (± 0.51%)	2.44s (± 0.40%)	-0.01s (- 0.61%)	2.41s	2.46s
Bind Time	0.99s (± 0.75%)	0.98s (± 0.76%)	-0.01s (- 0.71%)	0.97s	1.00s
Check Time	4.81s (± 0.44%)	4.79s (± 0.57%)	-0.01s (- 0.31%)	4.75s	4.85s
Emit Time	5.91s (± 1.20%)	5.92s (± 1.23%)	+0.02s (+ 0.25%)	5.76s	6.09s
Total Time	14.17s (± 0.45%)	14.15s (± 0.55%)	-0.02s (- 0.13%)	14.04s	14.38s
Monaco - node (v8.9.0, x86)
Memory used	193,429k (± 0.02%)	193,456k (± 0.02%)	+28k (+ 0.01%)	193,356k	193,532k
Parse Time	1.90s (± 0.69%)	1.91s (± 0.80%)	+0.01s (+ 0.26%)	1.88s	1.94s
Bind Time	0.70s (± 0.96%)	0.70s (± 0.95%)	+0.00s (+ 0.43%)	0.69s	0.72s
Check Time	5.48s (± 0.42%)	5.43s (± 1.33%)	-0.04s (- 0.82%)	5.18s	5.57s
Emit Time	2.67s (± 0.89%)	2.71s (± 3.00%)	+0.04s (+ 1.42%)	2.64s	3.03s
Total Time	10.74s (± 0.30%)	10.75s (± 0.47%)	+0.00s (+ 0.05%)	10.68s	10.87s
TFS - node (v8.9.0, x86)
Memory used	173,700k (± 0.02%)	173,689k (± 0.02%)	-11k (- 0.01%)	173,636k	173,793k
Parse Time	1.58s (± 0.87%)	1.60s (± 1.18%)	+0.02s (+ 1.01%)	1.56s	1.65s
Bind Time	0.63s (± 0.94%)	0.64s (± 0.75%)	+0.00s (+ 0.47%)	0.63s	0.65s
Check Time	4.60s (± 0.38%)	4.64s (± 0.89%)	+0.04s (+ 0.87%)	4.57s	4.76s
Emit Time	2.79s (± 0.85%)	2.78s (± 0.67%)	-0.01s (- 0.18%)	2.74s	2.83s
Total Time	9.61s (± 0.34%)	9.66s (± 0.50%)	+0.05s (+ 0.53%)	9.57s	9.81s
material-ui - node (v8.9.0, x86)
Memory used	262,557k (± 0.02%)	262,394k (± 0.02%)	-162k (- 0.06%)	262,243k	262,502k
Parse Time	2.44s (± 0.88%)	2.45s (± 0.56%)	+0.01s (+ 0.49%)	2.42s	2.48s
Bind Time	0.67s (± 0.71%)	0.67s (± 1.05%)	+0.00s (+ 0.30%)	0.66s	0.69s
Check Time	15.62s (± 0.76%)	15.77s (± 0.71%)	+0.15s (+ 0.98%)	15.58s	16.00s
Emit Time	0.00s (± 0.00%)	0.00s (± 0.00%)	0.00s ( NaN%)	0.00s	0.00s
Total Time	18.72s (± 0.60%)	18.89s (± 0.62%)	+0.17s (+ 0.89%)	18.69s	19.14s

System

Machine Name	ts-ci-ubuntu
Platform	linux 4.4.0-166-generic
Architecture	x64
Available Memory	16 GB
Available Memory	1 GB
CPUs	4 × Intel(R) Core(TM) i7-4770 CPU @ 3.40GHz

Hosts

• node (v10.16.3, x64)
• node (v12.1.0, x64)
• node (v8.9.0, x64)
• node (v8.9.0, x86)

Scenarios

• Angular - node (v10.16.3, x64)
• Angular - node (v12.1.0, x64)
• Angular - node (v8.9.0, x64)
• Angular - node (v8.9.0, x86)
• Monaco - node (v10.16.3, x64)
• Monaco - node (v12.1.0, x64)
• Monaco - node (v8.9.0, x64)
• Monaco - node (v8.9.0, x86)
• TFS - node (v10.16.3, x64)
• TFS - node (v12.1.0, x64)
• TFS - node (v8.9.0, x64)
• TFS - node (v8.9.0, x86)
• material-ui - node (v10.16.3, x64)
• material-ui - node (v12.1.0, x64)
• material-ui - node (v8.9.0, x64)
• material-ui - node (v8.9.0, x86)

Benchmark	Name	Iterations
Current	39393	10
Baseline	master	10

[Ron Buckton (rbuckton)]

I noticed some failures in the DT test run. I'm trying to determine if these are existing errors or are due to this change.

[Ron Buckton (rbuckton)]

It looks like the DT failures are issues in DT:

• eventsource has an incompatible definitions for MessageEventInit and MessageEvent due to changes in lib.dom.d.ts ('eventsource' DOM augmentations are incompatible with TypeScript 4.0 DefinitelyTyped/DefinitelyTyped#45935)
• testing-library__vue is broken because GetByRole in @testing-library/dom is overloaded and the BoundFunction type uses a conditional type with infer on a function type so it only picks one of the two overloads (which happens to be the wrong one for this case) ('testing-library__vue' tests are failing for 'getByRole' DefinitelyTyped/DefinitelyTyped#45937)
• knockout is failing because ko.observable is overloaded with a <T = any>(value: null): KnockoutObservable<T | null> which breaks its own tests. ('knockout' tests are failing due to overload resolution with 'null' on 'ko.observable' DefinitelyTyped/DefinitelyTyped#45938)