Ensure createProgram stops referencing rootNamesOrOptions to ensure oldProgram is GC'd

[jakebailey]

This is practically the same as #58138, since that seems to be the only thing that works, along with some code to make createProgram less likely to accidentally be changed such that this hack breaks something.

This is still 100% for sure a JSC GC bug, but I cannot find any reasonable way to fix this besides the original proposed solution.

The parameter rootNamesOrOptions holds a reference to oldProgram; we force overwrote oldProgram in the local scope, but rootNamesOrOptions appears to stay in scope in JSC, so overwrite that too. That and createProgramOptions also referenced the variable, so that has to also go.

Fixes #58137

[tmm1]

Thank you!!

I also tried several other variations and this is the only thing that seems to work. Clearly a JSC bug, but it is severe enough that a workaround is warranted.

[jakebailey]

Hmmm, actually, I have an idea...

[jakebailey]

Aha, I found a more explainable fix.

[jakebailey]

@typescript-bot pack this

This fix is way more explainable. I only realized it after I sent the PR.

[typescript-bot]

Starting jobs; this comment will be updated as builds start and complete.

Command	Status	Results
pack this	✅ Started	✅ Results

[typescript-bot]

Hey @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/164619/artifacts?artifactName=tgz&fileId=CD7BECBB0B9227A85A09E7CA9B0974942D47ABEF76E46CBA3A32CB1E3A825A5702&fileName=/typescript-5.8.0-insiders.20250123.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]".;

[jakebailey]

@typescript-bot perf test tsserver-only

[typescript-bot]

Starting jobs; this comment will be updated as builds start and complete.

Command	Status	Results
perf test tsserver-only	✅ Started	👀 Results

[tmm1]

Wow nice find.

[typescript-bot]

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

Here they are:

tsserver

Comparison Report - baseline..pr

Metric	baseline	pr	Delta	Best	Worst	p-value
Compiler-UnionsTSServer - node (v18.15.0, x64)
Req 1 - updateOpen	2,320ms (± 0.45%)	2,333ms (± 0.83%)	~	2,305ms	2,355ms	p=0.297 n=6
Req 2 - geterr	5,308ms (± 0.49%)	5,323ms (± 0.27%)	~	5,307ms	5,346ms	p=0.378 n=6
Req 3 - references	262ms (± 0.45%)	264ms (± 1.48%)	~	261ms	269ms	p=0.680 n=6
Req 4 - navto	227ms (± 0.66%)	224ms (± 0.23%)	-2ms (- 1.03%)	224ms	225ms	p=0.006 n=6
Req 5 - completionInfo count	1,357	1,357	~	~	~	p=1.000 n=6
Req 5 - completionInfo	79ms (± 8.89%)	84ms (±10.42%)	~	76ms	92ms	p=0.357 n=6
CompilerTSServer - node (v18.15.0, x64)
Req 1 - updateOpen	2,437ms (± 0.99%)	2,433ms (± 0.65%)	~	2,412ms	2,453ms	p=1.000 n=6
Req 2 - geterr	4,029ms (± 0.57%)	4,022ms (± 0.62%)	~	3,997ms	4,055ms	p=0.748 n=6
Req 3 - references	279ms (± 0.98%)	280ms (± 1.00%)	~	274ms	282ms	p=1.000 n=6
Req 4 - navto	227ms (± 0.18%)	227ms (± 0.18%)	~	226ms	227ms	p=1.000 n=6
Req 5 - completionInfo count	1,519	1,519	~	~	~	p=1.000 n=6
Req 5 - completionInfo	83ms (± 5.73%)	85ms (± 5.00%)	~	76ms	87ms	p=0.681 n=6
xstate-main-1-tsserver - node (v18.15.0, x64)
Req 1 - updateOpen	5,276ms (± 0.22%)	5,278ms (± 0.29%)	~	5,258ms	5,293ms	p=0.936 n=6
Req 2 - geterr	1,153ms (± 1.26%)	1,154ms (± 1.76%)	~	1,135ms	1,188ms	p=0.810 n=6
Req 3 - references	76ms (± 0.68%)	75ms	-1ms (- 0.88%)	~	~	p=0.025 n=6
Req 4 - navto	445ms (± 0.81%)	445ms (± 1.20%)	~	434ms	448ms	p=1.000 n=6
Req 5 - completionInfo count	3,462	3,462	~	~	~	p=1.000 n=6
Req 5 - completionInfo	834ms (± 0.96%)	840ms (± 1.58%)	~	827ms	859ms	p=0.688 n=6

System info unknown

Hosts

• node (v18.15.0, x64)

Scenarios

• CompilerTSServer - node (v18.15.0, x64)
• Compiler-UnionsTSServer - node (v18.15.0, x64)
• xstate-main-1-tsserver - node (v18.15.0, x64)

Benchmark	Name	Iterations
Current	pr	6
Baseline	baseline	6

Developer Information:

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