Fix a logic-changing typo in getRecursionIdentity

[angryzor]

There is currently a typo bug in the getRecursionIdentity function that changes the logic of the function in an unexpected way. This PR fixes that bug.

Please verify that:

• There is an associated issue in the Backlog milestone (required)
• Code is up-to-date with the main branch
• You've successfully run hereby runtests locally
• There are new or updated unit tests validating the change - there is no new functionality added, this PR fixes a small (1 character) logic mistake in the existing code

Fixes #54320

[jakebailey]

@typescript-bot test this
@typescript-bot test top100
@typescript-bot user test this
@typescript-bot run dt
@typescript-bot perf test this faster

[typescript-bot]

Heya @jakebailey, I've started to run the diff-based top-repos suite on this PR at 8e185f5. You can monitor the build here.

Update: The results are in!

[typescript-bot]

Heya @jakebailey, I've started to run the extended test suite on this PR at 8e185f5. You can monitor the build here.

[typescript-bot]

Heya @jakebailey, I've started to run the abridged perf test suite on this PR at 8e185f5. You can monitor the build here.

Update: The results are in!

[typescript-bot]

Heya @jakebailey, I've started to run the parallelized Definitely Typed test suite on this PR at 8e185f5. You can monitor the build here.

Update: The results are in!

[typescript-bot]

Heya @jakebailey, I've started to run the diff-based user code test suite on this PR at 8e185f5. You can monitor the build here.

Update: The results are in!

[typescript-bot]

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

Here they are:

Comparison Report - main..54321

Metric	main	54321	Delta	Best	Worst	p-value
Angular - node (v16.17.1, x64)
Memory used	365,139k (± 0.01%)	365,066k (± 0.02%)	~	365,002k	365,160k	p=0.066 n=6
Parse Time	3.56s (± 0.86%)	3.55s (± 0.15%)	~	3.55s	3.56s	p=0.797 n=6
Bind Time	1.18s (± 0.69%)	1.19s (± 0.98%)	~	1.17s	1.20s	p=0.401 n=6
Check Time	9.62s (± 0.38%)	9.59s (± 0.57%)	~	9.50s	9.65s	p=0.520 n=6
Emit Time	8.00s (± 0.65%)	7.94s (± 0.87%)	~	7.86s	8.02s	p=0.128 n=6
Total Time	22.36s (± 0.44%)	22.27s (± 0.52%)	~	22.08s	22.37s	p=0.107 n=6
Compiler-Unions - node (v16.17.1, x64)
Memory used	192,916k (± 0.04%)	192,957k (± 0.04%)	~	192,859k	193,020k	p=0.470 n=6
Parse Time	1.60s (± 0.97%)	1.61s (± 1.04%)	~	1.58s	1.63s	p=0.171 n=6
Bind Time	0.83s (± 0.98%)	0.83s (± 0.00%)	~	0.83s	0.83s	p=0.405 n=6
Check Time	10.25s (± 0.54%)	10.21s (± 0.72%)	~	10.08s	10.28s	p=0.334 n=6
Emit Time	3.01s (± 0.80%)	3.02s (± 1.02%)	~	2.98s	3.07s	p=0.629 n=6
Total Time	15.70s (± 0.29%)	15.67s (± 0.62%)	~	15.53s	15.81s	p=0.627 n=6
Monaco - node (v16.17.1, x64)
Memory used	345,884k (± 0.01%)	345,866k (± 0.00%)	~	345,841k	345,884k	p=0.377 n=6
Parse Time	2.73s (± 0.83%)	2.73s (± 0.38%)	~	2.72s	2.75s	p=0.100 n=6
Bind Time	1.08s (± 0.50%)	1.09s (± 0.82%)	~	1.08s	1.10s	p=0.341 n=6
Check Time	7.84s (± 0.29%)	7.85s (± 0.41%)	~	7.83s	7.91s	p=0.869 n=6
Emit Time	4.49s (± 1.09%)	4.45s (± 0.48%)	~	4.43s	4.48s	p=0.075 n=6
Total Time	16.14s (± 0.49%)	16.12s (± 0.23%)	~	16.08s	16.18s	p=0.872 n=6
TFS - node (v16.17.1, x64)
Memory used	299,958k (± 0.01%)	299,960k (± 0.01%)	~	299,935k	299,982k	p=1.000 n=6
Parse Time	2.17s (± 0.68%)	2.17s (± 0.82%)	~	2.15s	2.20s	p=1.000 n=6
Bind Time	1.24s (± 0.88%)	1.24s (± 0.79%)	~	1.23s	1.25s	p=0.859 n=6
Check Time	7.29s (± 0.40%)	7.29s (± 0.47%)	~	7.25s	7.33s	p=0.808 n=6
Emit Time	4.33s (± 1.04%)	4.37s (± 0.66%)	~	4.33s	4.41s	p=0.147 n=6
Total Time	15.02s (± 0.31%)	15.06s (± 0.42%)	~	14.96s	15.14s	p=0.298 n=6
material-ui - node (v16.17.1, x64)
Memory used	480,937k (± 0.01%)	480,940k (± 0.01%)	~	480,895k	480,980k	p=0.810 n=6
Parse Time	3.25s (± 0.45%)	3.26s (± 0.60%)	~	3.24s	3.28s	p=0.188 n=6
Bind Time	0.94s (± 0.43%)	0.94s (± 0.55%)	~	0.94s	0.95s	p=0.595 n=6
Check Time	17.83s (± 0.58%)	17.93s (± 0.83%)	~	17.76s	18.11s	p=0.423 n=6
Emit Time	0.00s (± 0.00%)	0.00s (± 0.00%)	~	0.00s	0.00s	p=1.000 n=6
Total Time	22.02s (± 0.52%)	22.14s (± 0.72%)	~	21.94s	22.34s	p=0.173 n=6
xstate - node (v16.17.1, x64)
Memory used	560,512k (± 0.01%)	560,517k (± 0.03%)	~	560,390k	560,817k	p=0.378 n=6
Parse Time	4.01s (± 0.41%)	4.03s (± 0.16%)	~	4.02s	4.04s	p=0.073 n=6
Bind Time	1.77s (± 0.46%)	1.78s (± 0.55%)	~	1.77s	1.79s	p=0.065 n=6
Check Time	3.05s (± 0.86%)	3.07s (± 0.63%)	~	3.04s	3.09s	p=0.259 n=6
Emit Time	0.09s (± 6.44%)	0.09s (± 0.00%)	~	0.09s	0.09s	p=0.071 n=6
Total Time	8.92s (± 0.46%)	8.97s (± 0.27%)	+0.05s (+ 0.50%)	8.93s	8.99s	p=0.045 n=6

System

Machine Name	ts-ci-ubuntu
Platform	linux 5.4.0-148-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

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

Benchmark	Name	Iterations
Current	54321	6
Baseline	main	6

Developer Information:

Download Benchmark

[typescript-bot]

@jakebailey Here are the results of running the user test suite comparing main and refs/pull/54321/merge:

There were infrastructure failures potentially unrelated to your change:

• 1 instance of "Unknown failure"
• 1 instance of "Package install failed"

Otherwise...

Everything looks good!

[fatcerberus]

There are new or updated unit tests validating the change - there is no new functionality added, this PR fixes a small (1 character) logic mistake in the existing code

Of course this is a bug either way, but ideally there would be a regression test… does this observably change the behavior of any TS code?

[typescript-bot]

@jakebailey Here are the results of running the top-repos suite comparing main and refs/pull/54321/merge:

Everything looks good!

[angryzor]

There are new or updated unit tests validating the change - there is no new functionality added, this PR fixes a small (1 character) logic mistake in the existing code

Of course this is a bug either way, but ideally there would be a regression test… does this observably change the behavior of any TS code?

The problem is that I stumbled upon this completely by accident while reading the source trying to understand how the infinite recursion prevention mechanism works (because my fork was infinitely recursing 😅). In other words I currently do not understand this part of the code base well enough to know with certainty what functionality this bug may affect. If there is a noticeable effect for the end user then it was in any case not covered by existing unit tests as these pass without any modification.

I can tell you however that the bug is currently mostly masked by the additional condition right after it: && (type as TypeReference).node. This extra check significantly narrows down the types that could end up in this conditional branch. After looking at the existing Type classes there are only 3 that include this property and thus could possibly end up in this branch:

• TypeReference
• DeferredTypeReference
• InstantiationExpressionType

The first 2 are obviously fine as they are the types that are supposed to end up in that branch, just the last one needs to be verified.

[typescript-bot]

Hey @jakebailey, the results of running the DT tests are ready.
Everything looks the same!
You can check the log here.