Infer AssertsIdentifier type predicates by danvk · Pull Request #58495 · microsoft/TypeScript

Dan Vanderkam (danvk) · 2024-05-10T16:55:13Z

This extends the type predicate inference from #57465 to cover "asserts identifier" predicates as well. For example:

// function isNumber(x: unknown): asserts x is numberfunctionisNumber(x: unknown){if(typeofx!=='number'){thrownewError(`expected a number, got ${x}`);}}

or:

// function assertNonNullish<T>(x: T): asserts x is NonNullable<T>functionassertNonNullish<T>(x: T){if(x!=null){return;}thrownewError();}

The constraints for inference are:

We're working with a function statement. Not a constructor, getter, setter, method, arrow function, or function expression. (This is significantly more restrictive than for "identifier" predicates, see Error when assertion function calls aren't CFA'd #33622 for why.)
The function does not have an explicit return type annotation, but is inferred to return void or undefined.
The function takes at least one parameter that it does not mutate.

The criterion winds up being a bit simpler than it was in #57465:

Check the type of the parameter at each return site (including an implicit return at the end of the function).
Union these types.
If this is different than the initial type of the parameter, then we've got an assertion function.

I wound up implementing "different than" with an assignability check since branching constructs can sometimes change the representation of a parameter's type in superficial ways, e.g. unknown can become {} | null | undefined.

There's no equivalent of the "false check" that we needed to infer identifier type predicates. Assertion predicates are inherently one-sided. If they fail, your code will throw. This means that we can infer assertions even when the negative type can't be represented. For example:

// function assertIsShortString(x: unknown): asserts x is stringfunctionassertIsShortString(x: unknown){if(typeofx!=='string'){thrownewError('Expected string');}elseif(x.length>10){thrownewError('Expected short string');}}

This wouldn't work as a type predicate (x is string) because you can't represent "all types except short strings." But it's fine as an imprecise assertion, since there's no way to observe the negative case.

A few other things to note:

This allows assertions to flow (Type predicate assertion does not carry over when used in another function #51326). In particular, this lets CFA "see through" a function that calls a type predicate and throws if it fails (e.g. assertFoo calls isFoo).
This only infers assertions with a type: asserts x is T, not asserts x. The latter would also be interesting, but that feels like a different problem.
This only infers a non-returning code path via its effect on types. This feels a little strange/risky to me since it means this code runs on all sorts of functions that don't throw. But it does work, and this is a natural way to handle all the different patterns (early throw, early return).
One of the fourslash tests found a bug with unused parameters getting marked as used. This turns out to be an issue with inferred type predicates as well, see Regression in detecting unused parameters in 5.5.0-beta #58493.

It's possible that the "asserted type" really is the same as the parameter's declared type, but TS isn't able to figure that out. This happened for one of the baselines. In this case we'll infer a useless type predicate (function f(x: T): asserts x is T). This is noisy but won't produce spurious errors. There's one example of this in the baselines.

I didn't observe any slowdowns from this change locally and there's some reason to hope that's the case. For inferred type predicates, the expensive part was the "false" checks (see #57465 (comment)). There's no need to do that for assertion functions, though, so we won't pay that price. On the other hand, there might be more implicitly void-returning functions than implicitly boolean-returning functions, so we'll see!

Dan Vanderkam (danvk) · 2024-05-10T16:57:00Z

+ // An assignability check covers this, but a void initType can become an undefined type through control flow analysis.
+ // Since void is not assignable to undefined, we patch initType to handle this, too.
+ const assertedType = getUnionType(typesAtReturn, UnionReduction.Subtype);
+ const patchedInitType = mapType(initType, t => t.flags & TypeFlags.Void ? undefinedType : t);


This is because void changes to undefined in this function, and undefined is not assignable to void:
functionbooleanOrVoid(a: boolean|void){if(typeofa==="undefined"){a}a// undefined}
This feels like a hack, though, and I'd love to change it if there's a cleaner fix.

Dan Vanderkam (danvk) · 2024-05-10T16:58:31Z

 test9?: any;
 }): void;
-declare function fa1(x: [true, number] | [false, string]): void;
+declare function fa1(x: [true, number] | [false, string]): asserts x is [false, string];


This one is a little weird (the function never returns), but it follows from the types: TS understands that for(;;) {} is an infinite loop, but not while(!!true) {}.

Dan Vanderkam (danvk) · 2024-05-10T17:01:38Z

 function keyofNarrowing<S extends { [K in keyof S]: string }>(k: keyof S) {
->keyofNarrowing : <S extends { [K in keyof S]: string; }>(k: keyof S) => void
-> : ^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^^ ^^^^^^^^^
+>keyofNarrowing : <S extends { [K in keyof S]: string; }>(k: keyof S) => asserts k is (keyof S & number) | (keyof S & symbol) | (keyof S & string)


This is the one loss: the other changes are all valid predicates.
// asserts k is (keyof S & number) | (keyof S & symbol) | (keyof S & string)functionkeyofNarrowing<Sextends{[KinkeyofS]: string}>(k: keyofS){ ... }
This should not be an assertion function because:
(keyof S & number) | (keyof S & symbol) | (keyof S & string) = keyof S & (number | symbol | string) = keyof S & PropertyKey = keyof S
TS isn't able to figure that out, however, so we get a meaningless assertion predicate.

Dan Vanderkam (danvk) · 2024-05-10T17:03:07Z

 used1; used2;

-function f() {
+function f(a, b) {


This diff is clearly wrong and a bug in my PR. There's a similar issue with the existing inferred type predicates change, see #58493. The fix for that should also apply here.

I confirmed that Mateusz Burzyński (@Andarist)'s PR #58514 also fixes this.

Bruce Pascoe (fatcerberus) · 2024-05-10T17:14:04Z

If this is different than the initial type of the parameter, then we've got an assertion function.

This feels like it’s going to turn a lot of functions into assertions that were never intended to be, just because a parameter was narrowed somewhere in the function.

Dan Vanderkam (danvk) · 2024-05-10T17:38:52Z

If this is different than the initial type of the parameter, then we've got an assertion function.
This feels like it’s going to turn a lot of functions into assertions that were never intended to be, just because a parameter was narrowed somewhere in the function.

It's not enough for the parameter to be narrowed somewhere in the function. The function has to throw in a way that's tied to that narrowing.

We could do an experiment similar to #58173 to see how often this triggers.

Bruce Pascoe (fatcerberus) · 2024-05-10T17:48:28Z

Ah, okay - you didn’t mention that in the description in the OP, the algorithm you laid out was just that you check all the return points, not also the throwing points.

Dan Vanderkam (danvk) · 2024-05-10T18:15:45Z

Ah, okay - you didn’t mention that in the description in the OP, the algorithm you laid out was just that you check all the return points, not also the throwing points.

The algorithm only looks at parameter types when you return, or (important!) at the implicit return at the end of a function. When you union those types, the only way I can think of that you'd get something distinct from the initial parameter type is by having a code path that throws or does the equivalent (calls another assertion function or never-returning function, or goes into an infinite loop).

Maybe an example would make it clearer how this works:

functionassertABC(x: 'A'|'B'|'C'|'D'|'E'){if(x==='A'){return;// type of x here is 'A'}elseif(x==='B'||x==='C'){thrownewError();}// implicit return; type of x here is 'D' | E'}

Unioning the types of x gives 'A' | 'D' | 'E'. Since 'A' | D' | 'E' is distinct from 'A' | 'B' | 'C' | 'D' | 'E', we have a type assertion function.

If you take a look at the code for the algorithm, it's all about return. The association with throw is implied by the check on the types.

Bruce Pascoe (fatcerberus) · 2024-05-10T20:10:41Z

Ah, so it’s based on how TS re-merges control-flow branches by unioning the narrowed types back together, that’s clever. However do note - that can sometimes create an observably different type on the other side (see: subtype reduction, introducing intersections, etc.)

Bruce Pascoe (fatcerberus) · 2024-05-10T20:11:51Z

Forgive me if you’ve accounted for all this already - I’m just spouting the caveats that come to mind when I think about this.

Dan Vanderkam (danvk) · 2024-05-10T21:06:09Z

Ah, so it’s based on how TS re-merges control-flow branches by unioning the narrowed types back together, that’s clever. However do note - that can sometimes create an observably different type on the other side (see: subtype reduction, introducing intersections, etc.)

I won't infer an assertion predicate so long as the initial parameter type is assignable to the asserted type, so superficial differences shouldn't matter. But there are some cases where TS can't figure out the relationship. There's one example of this in the baselines (see my comments on the code). There will probably be others in the wild.

This change would feel less aggressive if I could detect whether there was a code path that throws in the function, but I couldn't find anything that quite did what I wanted.

Jake Bailey (jakebailey) · 2024-05-10T21:09:10Z

TypeScript Bot (@typescript-bot) test it
TypeScript Bot (@typescript-bot) pack this

for fun

TypeScript Bot (typescript-bot) · 2024-05-10T21:09:12Z

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

Command	Status	Results
`test top400`	✅ Started	👀 Results
`user test this`	✅ Started	✅ Results
`run dt`	✅ Started	✅ Results
`perf test this faster`	✅ Started	👀 Results
`pack this`	✅ Started	✅ Results

TypeScript Bot (typescript-bot) · 2024-05-10T21:14:13Z

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/161690/artifacts?artifactName=tgz&fileId=0BFA3D3A0A0BB0B903EE356283DCF9D638B724930087ECCE5D71B4C18A4DA8BB02&fileName=/typescript-5.5.0-insiders.20240510.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@5.5.0-pr-58495-9".;

TypeScript Bot (typescript-bot) · 2024-05-10T21:28:07Z

Hey Jake Bailey (@jakebailey), the results of running the DT tests are ready.

Everything looks the same!

You can check the log here.

TypeScript Bot (typescript-bot) · 2024-05-10T21:28:08Z

Jake Bailey (@jakebailey) Here are the results of running the user tests comparing main and refs/pull/58495/merge:

Everything looks good!

TypeScript Bot (typescript-bot) · 2024-05-10T21:44:50Z

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

Here they are:

tsc

Comparison Report - baseline..pr

_Metric	_baseline	_pr	_Delta	_Best	_Worst	_p-value
_{Compiler-Unions - node (v18.15.0, x64)}
_Errors	₃₀	₃₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_62,154	_62,154	_~	_~	_~	_{p=1.000 n=6}
_Types	_50,248	_50,255	_{+7 (+ 0.01%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{192,824k (± 0.77%)}	_{193,524k (± 0.95%)}	_{+700k (+ 0.36%)}	_192,296k	_195,932k	_{p=0.031 n=6}
_{Parse Time}	_{1.55s (± 1.08%)}	_{1.54s (± 1.95%)}	_~	_1.51s	_1.58s	_{p=0.681 n=6}
_{Bind Time}	_{0.86s (± 1.40%)}	_{0.86s (± 0.47%)}	_~	_0.86s	_0.87s	_{p=0.863 n=6}
_{Check Time}	_{11.29s (± 0.59%)}	_{11.32s (± 0.63%)}	_~	_11.23s	_11.40s	_{p=0.748 n=6}
_{Emit Time}	_{3.15s (± 0.33%)}	_{3.14s (± 0.82%)}	_~	_3.11s	_3.19s	_{p=0.112 n=6}
_{Total Time}	_{16.86s (± 0.49%)}	_{16.86s (± 0.43%)}	_~	_16.74s	_16.93s	_{p=0.872 n=6}
_{angular-1 - node (v18.15.0, x64)}
_Errors	₅	₅	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_944,110	_944,107	_{-3 (- 0.00%)}	_~	_~	_{p=0.001 n=6}
_Types	_407,140	_407,147	_{+7 (+ 0.00%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{1,222,027k (± 0.00%)}	_{1,222,174k (± 0.00%)}	_{+147k (+ 0.01%)}	_1,222,093k	_1,222,232k	_{p=0.008 n=6}
_{Parse Time}	_{8.07s (± 0.31%)}	_{8.12s (± 0.64%)}	_{+0.05s (+ 0.66%)}	_8.05s	_8.20s	_{p=0.043 n=6}
_{Bind Time}	_{2.25s (± 0.67%)}	_{2.25s (± 0.73%)}	_~	_2.22s	_2.26s	_{p=1.000 n=6}
_{Check Time}	_{36.49s (± 0.33%)}	_{36.59s (± 0.44%)}	_~	_36.34s	_36.81s	_{p=0.229 n=6}
_{Emit Time}	_{17.53s (± 0.66%)}	_{17.57s (± 0.40%)}	_~	_17.49s	_17.69s	_{p=0.423 n=6}
_{Total Time}	_{64.33s (± 0.30%)}	_{64.53s (± 0.24%)}	_~	_64.28s	_64.70s	_{p=0.109 n=6}
_{mui-docs - node (v18.15.0, x64)}
_Errors	₅	₅	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_1,961,283	_1,961,283	_~	_~	_~	_{p=1.000 n=6}
_Types	_696,900	_696,939	_{+39 (+ 0.01%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{1,777,974k (± 0.00%)}	_{1,778,082k (± 0.00%)}	_{+108k (+ 0.01%)}	_1,778,048k	_1,778,110k	_{p=0.005 n=6}
_{Parse Time}	_{9.86s (± 0.38%)}	_{9.86s (± 0.31%)}	_~	_9.81s	_9.90s	_{p=0.686 n=6}
_{Bind Time}	_{3.36s (± 0.71%)}	_{3.37s (± 0.82%)}	_~	_3.32s	_3.40s	_{p=0.370 n=6}
_{Check Time}	_{82.68s (± 0.18%)}	_{82.72s (± 0.23%)}	_~	_82.45s	_83.02s	_{p=1.000 n=6}
_{Emit Time}	_{0.21s (± 3.95%)}	_{0.20s (± 2.54%)}	_~	_0.20s	_0.21s	_{p=0.523 n=6}
_{Total Time}	_{96.12s (± 0.12%)}	_{96.15s (± 0.22%)}	_~	_95.89s	_96.49s	_{p=1.000 n=6}
_{self-build-src - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_1,220,400	_1,220,443	_{+43 (+ 0.00%)}	_~	_~	_{p=0.001 n=6}
_Types	_258,967	_258,989	_{+22 (+ 0.01%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{2,335,959k (± 0.03%)}	_{2,336,372k (± 0.04%)}	_~	_2,335,223k	_2,337,305k	_{p=0.471 n=6}
_{Parse Time}	_{4.97s (± 1.31%)}	_{4.95s (± 0.83%)}	_~	_4.91s	_5.00s	_{p=0.378 n=6}
_{Bind Time}	_{1.88s (± 0.73%)}	_{1.88s (± 0.93%)}	_~	_1.85s	_1.90s	_{p=1.000 n=6}
_{Check Time}	_{33.77s (± 0.36%)}	_{33.79s (± 0.32%)}	_~	_33.62s	_33.91s	_{p=0.936 n=6}
_{Emit Time}	_{2.65s (± 2.29%)}	_{2.63s (± 2.95%)}	_~	_2.51s	_2.74s	_{p=0.521 n=6}
_{Total Time}	_{43.30s (± 0.24%)}	_{43.25s (± 0.29%)}	_~	_43.02s	_43.37s	_{p=0.575 n=6}
_{self-build-src-public-api - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_1,220,400	_1,220,443	_{+43 (+ 0.00%)}	_~	_~	_{p=0.001 n=6}
_Types	_258,967	_258,989	_{+22 (+ 0.01%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{2,411,497k (± 0.01%)}	_{2,411,343k (± 0.02%)}	_~	_2,410,547k	_2,412,209k	_{p=0.575 n=6}
_{Parse Time}	_{6.31s (± 0.60%)}	_{6.30s (± 0.90%)}	_~	_6.22s	_6.38s	_{p=0.810 n=6}
_{Bind Time}	_{2.05s (± 0.95%)}	_{2.04s (± 1.13%)}	_~	_2.02s	_2.07s	_{p=0.808 n=6}
_{Check Time}	_{40.18s (± 0.36%)}	_{40.26s (± 0.30%)}	_~	_40.09s	_40.45s	_{p=0.298 n=6}
_{Emit Time}	_{3.20s (± 2.60%)}	_{3.19s (± 1.84%)}	_~	_3.08s	_3.25s	_{p=0.470 n=6}
_{Total Time}	_{51.75s (± 0.42%)}	_{51.79s (± 0.29%)}	_~	_51.61s	_52.01s	_{p=0.689 n=6}
_{self-compiler - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_256,559	_256,601	_{+42 (+ 0.02%)}	_~	_~	_{p=0.001 n=6}
_Types	_104,270	_104,285	_{+15 (+ 0.01%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{425,708k (± 0.03%)}	_{425,822k (± 0.01%)}	_~	_425,752k	_425,882k	_{p=0.066 n=6}
_{Parse Time}	_{3.38s (± 0.63%)}	_{3.37s (± 0.49%)}	_~	_3.34s	_3.38s	_{p=0.331 n=6}
_{Bind Time}	_{1.31s (± 0.89%)}	_{1.31s (± 0.57%)}	_~	_1.30s	_1.32s	_{p=0.796 n=6}
_{Check Time}	_{17.93s (± 0.34%)}	_{17.97s (± 0.38%)}	_~	_17.87s	_18.03s	_{p=0.335 n=6}
_{Emit Time}	_{1.37s (± 2.14%)}	_1.37s	_~	_~	_~	_{p=0.655 n=6}
_{Total Time}	_{23.99s (± 0.22%)}	_{24.02s (± 0.29%)}	_~	_23.92s	_24.08s	_{p=0.688 n=6}
_{ts-pre-modules - node (v18.15.0, x64)}
_Errors	₃₅	₃₅	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_224,575	_224,583	_{+8 (+ 0.00%)}	_~	_~	_{p=0.001 n=6}
_Types	_93,785	_93,792	_{+7 (+ 0.01%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{369,898k (± 0.03%)}	_{369,935k (± 0.03%)}	_~	_369,870k	_370,123k	_{p=0.688 n=6}
_{Parse Time}	_{3.48s (± 0.47%)}	_{3.51s (± 0.67%)}	_~	_3.48s	_3.53s	_{p=0.122 n=6}
_{Bind Time}	_{1.93s (± 0.53%)}	_{1.93s (± 0.76%)}	_~	_1.92s	_1.96s	_{p=0.605 n=6}
_{Check Time}	_{19.36s (± 0.40%)}	_{19.36s (± 0.42%)}	_~	_19.26s	_19.49s	_{p=0.872 n=6}
_{Emit Time}	_0.00s	_0.00s	_~	_~	_~	_{p=1.000 n=6}
_{Total Time}	_{24.77s (± 0.35%)}	_{24.80s (± 0.34%)}	_~	_24.69s	_24.94s	_{p=0.748 n=6}
_{vscode - node (v18.15.0, x64)}
_Errors	₀	₂	_{🔻+2 (+ ∞%)}	_~	_~	_{p=0.001 n=6}
_Symbols	_2,820,491	_2,820,496	_{+5 (+ 0.00%)}	_~	_~	_{p=0.001 n=6}
_Types	_956,787	_956,831	_{+44 (+ 0.00%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{2,992,366k (± 0.00%)}	_{2,992,554k (± 0.00%)}	_{+188k (+ 0.01%)}	_2,992,461k	_2,992,599k	_{p=0.005 n=6}
_{Parse Time}	_{13.84s (± 0.33%)}	_{13.83s (± 0.36%)}	_~	_13.75s	_13.88s	_{p=0.936 n=6}
_{Bind Time}	_{4.16s (± 2.07%)}	_{4.30s (± 2.20%)}	_~	_4.11s	_4.37s	_{p=0.063 n=6}
_{Check Time}	_{73.32s (± 0.29%)}	_{73.45s (± 0.63%)}	_~	_72.95s	_74.28s	_{p=0.689 n=6}
_{Emit Time}	_{23.64s (± 0.62%)}	_{23.40s (± 0.60%)}	_{-0.24s (- 1.00%)}	_23.25s	_23.66s	_{p=0.020 n=6}
_{Total Time}	_{114.95s (± 0.22%)}	_{114.98s (± 0.52%)}	_~	_114.36s	_116.12s	_{p=0.689 n=6}
_{webpack - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_265,866	_265,866	_~	_~	_~	_{p=1.000 n=6}
_Types	_108,401	_108,402	_{+1 (+ 0.00%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{410,604k (± 0.01%)}	_{410,596k (± 0.01%)}	_~	_410,547k	_410,639k	_{p=1.000 n=6}
_{Parse Time}	_{4.77s (± 1.10%)}	_{4.75s (± 0.54%)}	_~	_4.71s	_4.79s	_{p=0.169 n=6}
_{Bind Time}	_{2.08s (± 0.88%)}	_{2.07s (± 1.22%)}	_~	_2.03s	_2.10s	_{p=0.622 n=6}
_{Check Time}	_{21.00s (± 0.26%)}	_{21.07s (± 0.28%)}	_~	_20.99s	_21.16s	_{p=0.093 n=6}
_{Emit Time}	_0.00s	_0.00s	_~	_~	_~	_{p=1.000 n=6}
_{Total Time}	_{27.85s (± 0.30%)}	_{27.88s (± 0.31%)}	_~	_27.79s	_28.03s	_{p=0.689 n=6}
_{xstate-main - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_524,576	_524,576	_~	_~	_~	_{p=1.000 n=6}
_Types	_178,847	_178,851	_{+4 (+ 0.00%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{462,623k (± 0.03%)}	_{462,577k (± 0.00%)}	_~	_462,533k	_462,600k	_{p=1.000 n=6}
_{Parse Time}	_{3.12s (± 1.24%)}	_{3.11s (± 0.86%)}	_~	_3.08s	_3.16s	_{p=0.570 n=6}
_{Bind Time}	_{1.17s (± 0.76%)}	_{1.17s (± 0.76%)}	_~	_1.16s	_1.18s	_{p=1.000 n=6}
_{Check Time}	_{18.21s (± 0.64%)}	_{18.21s (± 0.57%)}	_~	_18.08s	_18.33s	_{p=0.936 n=6}
_{Emit Time}	_0.00s	_0.00s	_~	_~	_~	_{p=1.000 n=6}
_{Total Time}	_{22.49s (± 0.49%)}	_{22.50s (± 0.42%)}	_~	_22.37s	_22.62s	_{p=0.873 n=6}

System info unknown

Hosts

node (v18.15.0, x64)

Scenarios

Compiler-Unions - node (v18.15.0, x64)
angular-1 - node (v18.15.0, x64)
mui-docs - node (v18.15.0, x64)
self-build-src - node (v18.15.0, x64)
self-build-src-public-api - node (v18.15.0, x64)
self-compiler - node (v18.15.0, x64)
ts-pre-modules - node (v18.15.0, x64)
vscode - node (v18.15.0, x64)
webpack - node (v18.15.0, x64)
xstate-main - node (v18.15.0, x64)

_Benchmark	_Name	_Iterations
_Current	_pr	₆
_Baseline	_baseline	₆

Developer Information:

Download Benchmarks

Dan Vanderkam (danvk) · 2024-05-10T22:46:29Z

Perf impact looks pretty minimal… but what are those two new errors in VS Code?

TypeScript Bot (typescript-bot) · 2024-05-10T22:51:51Z

Jake Bailey (@jakebailey) Here are the results of running the top 400 repos comparing main and refs/pull/58495/merge:

Something interesting changed - please have a look.

Details

darkreader/darkreader

1 of 5 projects failed to build with the old tsc and were ignored

tests/inject/tsconfig.json

error TS2775: Assertions require every name in the call target to be declared with an explicit type annotation.
- src/inject/dynamic-theme/adopted-style-manger.ts#L306

src/tsconfig.json

error TS2775: Assertions require every name in the call target to be declared with an explicit type annotation.
- src/inject/dynamic-theme/adopted-style-manger.ts#L306

src/api/tsconfig.json

error TS2775: Assertions require every name in the call target to be declared with an explicit type annotation.
- src/inject/dynamic-theme/adopted-style-manger.ts#L306

invoke-ai/InvokeAI

invokeai/frontend/web/tsconfig.json

error TS2775: Assertions require every name in the call target to be declared with an explicit type annotation.

microsoft/vscode

4 of 54 projects failed to build with the old tsc and were ignored

src/tsconfig.tsec.json

error TS2339: Property 'description' does not exist on type 'TreeItem'.
- src/vs/workbench/api/common/extHostTreeViews.ts#L821
error TS2339: Property 'accessibilityInformation' does not exist on type 'TreeItem'.
- src/vs/workbench/api/common/extHostTreeViews.ts#L830

src/tsconfig.json

error TS2339: Property 'description' does not exist on type 'TreeItem'.
- src/vs/workbench/api/common/extHostTreeViews.ts#L821
error TS2339: Property 'accessibilityInformation' does not exist on type 'TreeItem'.
- src/vs/workbench/api/common/extHostTreeViews.ts#L830

Bruce Pascoe (fatcerberus) · 2024-05-10T23:50:42Z

Assertions require every name in the call target to be declared with an explicit type annotation.

Ouch. I forgot that was something the compiler checked for. The existence of that error means you have to be very careful about exactly what you infer as an assertion…

Dan Vanderkam (danvk) · 2024-05-13T13:34:49Z

Summary of breaks (#58495 (comment)):

darkreader: we inferred that an arrow function was a type assertion predicate, which doesn't generally work.
InvokeAI: same; validateBaseCompatibility is an arrow function. This PR correctly infers that it returns a type assertion predicate, but this results in TS2775. If it were a function statement, the inferred type assertion predicate works fine.
vscode: In this case, we infer a type assertion predicate for a method. Again, this doesn't always work and can produce TS2776. But that's not what happens here. The ExtHostTreeView.validateTreeItem method becomes a type assertion predicate. This, in turn, exposes what I believe had been a latent TS bug: Narrowing by type predicate fails to produce intersection type with weak type #58518

The fix for all of these is to not infer type assertion predicates for methods or arrow functions because this can produce a confusing error at the call site. See #33622 for why. This definitely limits the scope of this PR: the latest version only runs on plain old function statements.

I think the nicest win from this PR is that it lets type predicates naturally flow through assertion wrappers:

declarefunctionisFoo(x: any): x is Foo;// function inferFromType(x: unknown): asserts x is FoofunctioninferFromType(x: unknown){if(!isFoo(x)){thrownewError();}}

Mateusz Burzyński (Andarist) · 2024-05-13T17:25:50Z

I think the nicest win from this PR is that it lets type predicates naturally flow through assertion wrappers:

This is dope 🚀

Jake Bailey (jakebailey) · 2024-05-13T17:57:49Z

TypeScript Bot (@typescript-bot) test it
TypeScript Bot (@typescript-bot) pack this

TypeScript Bot (typescript-bot) · 2024-05-13T17:57:51Z

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

Command	Status	Results
`test top400`	✅ Started	✅ Results
`user test this`	✅ Started	👀 Results
`run dt`	✅ Started	✅ Results
`perf test this faster`	✅ Started	👀 Results
`pack this`	✅ Started	✅ Results

TypeScript Bot (typescript-bot) · 2024-05-13T18:02:45Z

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/161715/artifacts?artifactName=tgz&fileId=33CA50AFB7B259ACD3FE936AA8261E8754CA2DEC5411359B7E3C7C6088AA876F02&fileName=/typescript-5.5.0-insiders.20240513.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@5.5.0-pr-58495-20".;

TypeScript Bot (typescript-bot) · 2024-05-13T18:20:57Z

Hey Jake Bailey (@jakebailey), the results of running the DT tests are ready.

Everything looks the same!

You can check the log here.

TypeScript Bot (typescript-bot) · 2024-05-13T18:25:03Z

Jake Bailey (@jakebailey) Here are the results of running the user tests comparing main and refs/pull/58495/merge:

Something interesting changed - please have a look.

Details

minimatch

/mnt/ts_downloads/_/m/minimatch/tsconfig.json

[NEW] error TS2775: Assertions require every name in the call target to be declared with an explicit type annotation.
- /mnt/ts_downloads/_/m/minimatch/node_modules/minimatch/minimatch.js(116,3)
- /mnt/ts_downloads/_/m/minimatch/node_modules/minimatch/minimatch.js(133,3)
- /mnt/ts_downloads/_/m/minimatch/node_modules/minimatch/minimatch.js(260,3)
- /mnt/ts_downloads/_/m/minimatch/node_modules/minimatch/minimatch.js(297,3)

TypeScript Bot (typescript-bot) · 2024-05-13T18:33:30Z

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

Here they are:

tsc

Comparison Report - baseline..pr

_Metric	_baseline	_pr	_Delta	_Best	_Worst	_p-value
_{Compiler-Unions - node (v18.15.0, x64)}
_Errors	₃₀	₃₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_62,154	_62,154	_~	_~	_~	_{p=1.000 n=6}
_Types	_50,248	_50,252	_{+4 (+ 0.01%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{193,496k (± 0.95%)}	_{195,371k (± 0.77%)}	_{+1,874k (+ 0.97%)}	_192,313k	_196,084k	_{p=0.020 n=6}
_{Parse Time}	_{1.55s (± 1.95%)}	_{1.55s (± 1.49%)}	_~	_1.51s	_1.58s	_{p=1.000 n=6}
_{Bind Time}	_{0.86s (± 0.94%)}	_{0.86s (± 0.47%)}	_~	_0.86s	_0.87s	_{p=0.584 n=6}
_{Check Time}	_{11.28s (± 0.34%)}	_{11.32s (± 0.32%)}	_~	_11.30s	_11.39s	_{p=0.081 n=6}
_{Emit Time}	_{3.14s (± 0.55%)}	_{3.13s (± 0.87%)}	_~	_3.09s	_3.16s	_{p=1.000 n=6}
_{Total Time}	_{16.83s (± 0.36%)}	_{16.86s (± 0.26%)}	_~	_16.82s	_16.94s	_{p=0.295 n=6}
_{angular-1 - node (v18.15.0, x64)}
_Errors	₅	₅	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_944,110	_944,111	_{+1 (+ 0.00%)}	_~	_~	_{p=0.001 n=6}
_Types	_407,140	_407,144	_{+4 (+ 0.00%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{1,222,086k (± 0.00%)}	_{1,222,194k (± 0.00%)}	_{+108k (+ 0.01%)}	_1,222,138k	_1,222,260k	_{p=0.020 n=6}
_{Parse Time}	_{6.78s (± 0.63%)}	_{6.77s (± 0.28%)}	_~	_6.75s	_6.80s	_{p=0.810 n=6}
_{Bind Time}	_{1.88s (± 0.64%)}	_{1.89s (± 0.40%)}	_~	_1.88s	_1.90s	_{p=0.111 n=6}
_{Check Time}	_{31.25s (± 0.53%)}	_{31.34s (± 0.43%)}	_~	_31.13s	_31.53s	_{p=0.298 n=6}
_{Emit Time}	_{14.72s (± 0.54%)}	_{14.77s (± 0.77%)}	_~	_14.64s	_14.93s	_{p=0.574 n=6}
_{Total Time}	_{54.62s (± 0.26%)}	_{54.77s (± 0.39%)}	_~	_54.55s	_55.03s	_{p=0.128 n=6}
_{mui-docs - node (v18.15.0, x64)}
_Errors	₅	₅	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_1,961,349	_1,961,349	_~	_~	_~	_{p=1.000 n=6}
_Types	_696,910	_696,910	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{1,778,101k (± 0.00%)}	_{1,778,109k (± 0.00%)}	_~	_1,778,068k	_1,778,142k	_{p=0.521 n=6}
_{Parse Time}	_{6.78s (± 0.31%)}	_{6.79s (± 0.59%)}	_~	_6.77s	_6.87s	_{p=0.655 n=6}
_{Bind Time}	_{2.31s (± 0.33%)}	_{2.31s (± 0.60%)}	_~	_2.29s	_2.32s	_{p=0.453 n=6}
_{Check Time}	_{57.05s (± 0.49%)}	_{56.97s (± 0.64%)}	_~	_56.51s	_57.51s	_{p=0.689 n=6}
_{Emit Time}	_0.14s	_0.14s	_~	_~	_~	_{p=1.000 n=6}
_{Total Time}	_{66.29s (± 0.43%)}	_{66.20s (± 0.52%)}	_~	_65.73s	_66.73s	_{p=0.575 n=6}
_{self-build-src - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_1,221,120	_1,221,163	_{+43 (+ 0.00%)}	_~	_~	_{p=0.001 n=6}
_Types	_259,211	_259,228	_{+17 (+ 0.01%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{2,337,130k (± 0.02%)}	_{2,337,212k (± 0.03%)}	_~	_2,336,192k	_2,338,326k	_{p=1.000 n=6}
_{Parse Time}	_{4.98s (± 1.51%)}	_{4.99s (± 0.83%)}	_~	_4.93s	_5.03s	_{p=1.000 n=6}
_{Bind Time}	_{1.87s (± 0.76%)}	_{1.88s (± 0.78%)}	_~	_1.86s	_1.90s	_{p=0.222 n=6}
_{Check Time}	_{33.72s (± 0.33%)}	_{33.81s (± 0.39%)}	_~	_33.64s	_33.96s	_{p=0.378 n=6}
_{Emit Time}	_{2.67s (± 1.96%)}	_{2.62s (± 2.44%)}	_~	_2.55s	_2.71s	_{p=0.172 n=6}
_{Total Time}	_{43.26s (± 0.29%)}	_{43.33s (± 0.23%)}	_~	_43.23s	_43.48s	_{p=0.378 n=6}
_{self-build-src-public-api - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_1,221,120	_1,221,163	_{+43 (+ 0.00%)}	_~	_~	_{p=0.001 n=6}
_Types	_259,211	_259,228	_{+17 (+ 0.01%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{2,411,894k (± 0.02%)}	_{2,412,608k (± 0.04%)}	_~	_2,411,592k	_2,413,650k	_{p=0.173 n=6}
_{Parse Time}	_{5.22s (± 0.95%)}	_{5.23s (± 1.18%)}	_~	_5.16s	_5.34s	_{p=0.873 n=6}
_{Bind Time}	_{1.69s (± 0.24%)}	_{1.69s (± 0.30%)}	_~	_1.69s	_1.70s	_{p=0.114 n=6}
_{Check Time}	_{34.31s (± 0.32%)}	_{34.26s (± 0.38%)}	_~	_34.08s	_34.45s	_{p=0.378 n=6}
_{Emit Time}	_{2.69s (± 0.47%)}	_{2.64s (± 3.18%)}	_~	_2.55s	_2.75s	_{p=0.378 n=6}
_{Total Time}	_{43.93s (± 0.30%)}	_{43.84s (± 0.45%)}	_~	_43.53s	_44.02s	_{p=0.521 n=6}
_{self-compiler - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_256,716	_256,758	_{+42 (+ 0.02%)}	_~	_~	_{p=0.001 n=6}
_Types	_104,288	_104,302	_{+14 (+ 0.01%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{425,755k (± 0.02%)}	_{425,930k (± 0.01%)}	_{+175k (+ 0.04%)}	_425,883k	_425,967k	_{p=0.005 n=6}
_{Parse Time}	_{3.37s (± 0.41%)}	_{3.38s (± 0.64%)}	_~	_3.35s	_3.41s	_{p=0.462 n=6}
_{Bind Time}	_{1.32s (± 0.68%)}	_{1.32s (± 0.89%)}	_~	_1.31s	_1.34s	_{p=0.672 n=6}
_{Check Time}	_{17.89s (± 0.42%)}	_{17.93s (± 0.29%)}	_~	_17.86s	_17.99s	_{p=0.297 n=6}
_{Emit Time}	_{1.35s (± 0.94%)}	_{1.37s (± 1.07%)}	_{+0.02s (+ 1.60%)}	_1.36s	_1.40s	_{p=0.032 n=6}
_{Total Time}	_{23.93s (± 0.29%)}	_{24.00s (± 0.21%)}	_{+0.07s (+ 0.31%)}	_23.94s	_24.07s	_{p=0.044 n=6}
_{ts-pre-modules - node (v18.15.0, x64)}
_Errors	₃₅	₃₅	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_224,575	_224,583	_{+8 (+ 0.00%)}	_~	_~	_{p=0.001 n=6}
_Types	_93,785	_93,791	_{+6 (+ 0.01%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{369,965k (± 0.04%)}	_{369,917k (± 0.02%)}	_~	_369,837k	_370,027k	_{p=1.000 n=6}
_{Parse Time}	_{2.82s (± 0.92%)}	_{2.83s (± 0.73%)}	_~	_2.81s	_2.86s	_{p=0.685 n=6}
_{Bind Time}	_{1.58s (± 0.84%)}	_{1.59s (± 1.04%)}	_~	_1.57s	_1.61s	_{p=0.738 n=6}
_{Check Time}	_{15.68s (± 0.48%)}	_{15.69s (± 0.22%)}	_~	_15.63s	_15.72s	_{p=0.809 n=6}
_{Emit Time}	_0.00s	_0.00s	_~	_~	_~	_{p=1.000 n=6}
_{Total Time}	_{20.09s (± 0.42%)}	_{20.11s (± 0.28%)}	_~	_20.03s	_20.19s	_{p=0.574 n=6}
_{vscode - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_2,821,517	_2,821,518	_{+1 (+ 0.00%)}	_~	_~	_{p=0.001 n=6}
_Types	_957,198	_957,198	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{2,993,753k (± 0.00%)}	_{2,993,703k (± 0.00%)}	_~	_2,993,596k	_2,993,776k	_{p=0.230 n=6}
_{Parse Time}	_{13.80s (± 0.26%)}	_{13.82s (± 0.11%)}	_~	_13.80s	_13.84s	_{p=0.167 n=6}
_{Bind Time}	_{4.14s (± 0.52%)}	_{4.14s (± 0.36%)}	_~	_4.13s	_4.17s	_{p=0.742 n=6}
_{Check Time}	_{73.44s (± 0.34%)}	_{73.18s (± 0.19%)}	_~	_73.02s	_73.37s	_{p=0.066 n=6}
_{Emit Time}	_{23.48s (± 0.35%)}	_{23.51s (± 0.67%)}	_~	_23.32s	_23.73s	_{p=0.873 n=6}
_{Total Time}	_{114.86s (± 0.23%)}	_{114.65s (± 0.15%)}	_~	_114.44s	_114.94s	_{p=0.199 n=6}
_{webpack - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_265,866	_265,866	_~	_~	_~	_{p=1.000 n=6}
_Types	_108,401	_108,401	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{410,651k (± 0.03%)}	_{410,560k (± 0.02%)}	_~	_410,508k	_410,651k	_{p=0.128 n=6}
_{Parse Time}	_{4.76s (± 0.84%)}	_{4.77s (± 1.23%)}	_~	_4.68s	_4.85s	_{p=0.936 n=6}
_{Bind Time}	_{2.07s (± 0.66%)}	_{2.05s (± 0.95%)}	_{-0.02s (- 1.21%)}	_2.02s	_2.07s	_{p=0.033 n=6}
_{Check Time}	_{20.98s (± 0.36%)}	_{20.96s (± 0.27%)}	_~	_20.89s	_21.04s	_{p=0.378 n=6}
_{Emit Time}	_0.00s	_0.00s	_~	_~	_~	_{p=1.000 n=6}
_{Total Time}	_{27.82s (± 0.38%)}	_{27.77s (± 0.30%)}	_~	_27.68s	_27.87s	_{p=0.295 n=6}
_{xstate-main - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_524,639	_524,639	_~	_~	_~	_{p=1.000 n=6}
_Types	_178,906	_178,906	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{462,735k (± 0.01%)}	_{462,750k (± 0.01%)}	_~	_462,650k	_462,811k	_{p=0.572 n=6}
_{Parse Time}	_{3.12s (± 0.81%)}	_{3.12s (± 0.55%)}	_~	_3.09s	_3.14s	_{p=0.807 n=6}
_{Bind Time}	_{1.16s (± 0.35%)}	_{1.16s (± 1.18%)}	_~	_1.15s	_1.18s	_{p=0.796 n=6}
_{Check Time}	_{18.34s (± 0.58%)}	_{18.35s (± 0.54%)}	_~	_18.16s	_18.44s	_{p=1.000 n=6}
_{Emit Time}	_0.00s	_{0.00s (±244.70%)}	_~	_0.00s	_0.01s	_{p=0.405 n=6}
_{Total Time}	_{22.63s (± 0.52%)}	_{22.63s (± 0.44%)}	_~	_22.46s	_22.73s	_{p=1.000 n=6}

System info unknown

Hosts

node (v18.15.0, x64)

Scenarios

Compiler-Unions - node (v18.15.0, x64)
angular-1 - node (v18.15.0, x64)
mui-docs - node (v18.15.0, x64)
self-build-src - node (v18.15.0, x64)
self-build-src-public-api - node (v18.15.0, x64)
self-compiler - node (v18.15.0, x64)
ts-pre-modules - node (v18.15.0, x64)
vscode - node (v18.15.0, x64)
webpack - node (v18.15.0, x64)
xstate-main - node (v18.15.0, x64)

_Benchmark	_Name	_Iterations
_Current	_pr	₆
_Baseline	_baseline	₆

Developer Information:

Download Benchmarks

TypeScript Bot (typescript-bot) · 2024-05-13T19:42:06Z

Jake Bailey (@jakebailey) Here are the results of running the top 400 repos comparing main and refs/pull/58495/merge:

Everything looks good!

Dan Vanderkam (danvk) · 2024-05-15T13:33:34Z

At first I thought the minimatch break had something with old-fashioned JS constructor function statements that were inferred to be type predicates. But it turned out to be more straightforward. The relevant code is here and all the failures are calls to this function:

varMAX_PATTERN_LENGTH=1024*64varassertValidPattern=function(pattern){if(typeofpattern!=='string'){thrownewTypeError('invalid pattern')}if(pattern.length>MAX_PATTERN_LENGTH){thrownewTypeError('pattern is too long')}}

So I also need to exclude function expressions from inference, not just arrow functions.

TypeScript Bot (typescript-bot) · 2024-05-15T13:38:09Z

This PR doesn't have any linked issues. Please open an issue that references this PR. From there we can discuss and prioritise.

Bruce Pascoe (fatcerberus) · 2024-05-15T16:35:52Z

Ironically, inferring assertValidPattern as an assertion predicate is actually correct! But unfortunately it hits the limitation that requires them to be explicitly annotated...

Dan Vanderkam (danvk) · 2024-05-15T16:56:26Z

Ironically, inferring assertValidPattern as an assertion predicate is actually correct! But unfortunately it hits the limitation that requires them to be explicitly annotated...

Right. So far as I'm aware, the algorithm is correct: it will never infer a type assertion predicate that's inaccurate. But there are many situations (methods, arrow functions, function expressions) where it will push you right into TS2775 / TS2776.

Jake Bailey (jakebailey) · 2024-05-15T20:56:33Z

TypeScript Bot (@typescript-bot) test it
TypeScript Bot (@typescript-bot) pack this

TypeScript Bot (typescript-bot) · 2024-05-15T20:56:36Z

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

Command	Status	Results
`test top400`	✅ Started	✅ Results
`user test this`	✅ Started	✅ Results
`run dt`	✅ Started	✅ Results
`perf test this faster`	✅ Started	👀 Results
`pack this`	✅ Started	✅ Results

TypeScript Bot (typescript-bot) · 2024-05-15T21:02:11Z

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/161774/artifacts?artifactName=tgz&fileId=93993D75141F9F8A88E91035A3BFD6BBFA39DEB63210D37972D1CB42488948E902&fileName=/typescript-5.5.0-insiders.20240515.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@5.5.0-pr-58495-31".;

TypeScript Bot (typescript-bot) · 2024-05-15T21:17:20Z

Jake Bailey (@jakebailey) Here are the results of running the user tests comparing main and refs/pull/58495/merge:

Everything looks good!

TypeScript Bot (typescript-bot) · 2024-05-15T21:17:59Z

Hey Jake Bailey (@jakebailey), the results of running the DT tests are ready.

Everything looks the same!

You can check the log here.

TypeScript Bot (typescript-bot) · 2024-05-15T21:38:32Z

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

Here they are:

tsc

Comparison Report - baseline..pr

_Metric	_baseline	_pr	_Delta	_Best	_Worst	_p-value
_{Compiler-Unions - node (v18.15.0, x64)}
_Errors	₃₀	₃₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_62,154	_62,154	_~	_~	_~	_{p=1.000 n=6}
_Types	_50,248	_50,252	_{+4 (+ 0.01%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{194,089k (± 1.00%)}	_{192,991k (± 0.76%)}	_~	_192,282k	_195,989k	_{p=0.936 n=6}
_{Parse Time}	_{1.30s (± 0.93%)}	_{1.30s (± 0.31%)}	_~	_1.30s	_1.31s	_{p=0.863 n=6}
_{Bind Time}	_0.72s	_0.72s	_~	_~	_~	_{p=1.000 n=6}
_{Check Time}	_{9.53s (± 0.47%)}	_{9.59s (± 0.18%)}	_~	_9.57s	_9.61s	_{p=0.053 n=6}
_{Emit Time}	_{2.64s (± 0.62%)}	_{2.62s (± 0.95%)}	_~	_2.59s	_2.65s	_{p=0.462 n=6}
_{Total Time}	_{14.19s (± 0.41%)}	_{14.23s (± 0.29%)}	_~	_14.18s	_14.27s	_{p=0.332 n=6}
_{angular-1 - node (v18.15.0, x64)}
_Errors	₅	₅	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_944,110	_944,111	_{+1 (+ 0.00%)}	_~	_~	_{p=0.001 n=6}
_Types	_407,140	_407,144	_{+4 (+ 0.00%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{1,222,144k (± 0.00%)}	_{1,222,202k (± 0.01%)}	_~	_1,222,065k	_1,222,277k	_{p=0.149 n=6}
_{Parse Time}	_{6.80s (± 0.54%)}	_{6.79s (± 0.57%)}	_~	_6.76s	_6.86s	_{p=0.746 n=6}
_{Bind Time}	_{1.88s (± 0.27%)}	_{1.88s (± 0.52%)}	_~	_1.87s	_1.89s	_{p=0.348 n=6}
_{Check Time}	_{31.36s (± 0.50%)}	_{31.28s (± 0.36%)}	_~	_31.17s	_31.48s	_{p=0.470 n=6}
_{Emit Time}	_{14.80s (± 0.37%)}	_{14.78s (± 0.33%)}	_~	_14.72s	_14.85s	_{p=0.630 n=6}
_{Total Time}	_{54.84s (± 0.34%)}	_{54.72s (± 0.25%)}	_~	_54.56s	_54.87s	_{p=0.173 n=6}
_{mui-docs - node (v18.15.0, x64)}
_Errors	₅	₅	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_1,964,176	_1,964,176	_~	_~	_~	_{p=1.000 n=6}
_Types	_819,283	_819,283	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{1,849,631k (± 0.00%)}	_{1,849,667k (± 0.00%)}	_~	_1,849,599k	_1,849,710k	_{p=0.128 n=6}
_{Parse Time}	_{6.78s (± 0.27%)}	_{6.77s (± 0.45%)}	_~	_6.74s	_6.83s	_{p=0.677 n=6}
_{Bind Time}	_{2.30s (± 0.84%)}	_{2.28s (± 0.46%)}	_~	_2.27s	_2.30s	_{p=0.218 n=6}
_{Check Time}	_{58.72s (± 0.36%)}	_{58.76s (± 0.16%)}	_~	_58.64s	_58.91s	_{p=0.689 n=6}
_{Emit Time}	_{0.14s (± 2.88%)}	_{0.14s (± 5.69%)}	_~	_0.14s	_0.16s	_{p=1.000 n=6}
_{Total Time}	_{67.93s (± 0.31%)}	_{67.96s (± 0.12%)}	_~	_67.85s	_68.09s	_{p=0.936 n=6}
_{self-build-src - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_1,221,221	_1,221,264	_{+43 (+ 0.00%)}	_~	_~	_{p=0.001 n=6}
_Types	_259,523	_259,540	_{+17 (+ 0.01%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{2,362,550k (± 2.61%)}	_{2,362,575k (± 2.60%)}	_~	_2,336,165k	_2,488,304k	_{p=0.936 n=6}
_{Parse Time}	_{5.02s (± 0.73%)}	_{4.97s (± 1.22%)}	_~	_4.91s	_5.04s	_{p=0.336 n=6}
_{Bind Time}	_{1.87s (± 0.48%)}	_{1.90s (± 0.97%)}	_{+0.03s (+ 1.52%)}	_1.88s	_1.93s	_{p=0.007 n=6}
_{Check Time}	_{33.82s (± 0.62%)}	_{33.94s (± 0.29%)}	_~	_33.80s	_34.04s	_{p=0.336 n=6}
_{Emit Time}	_{2.64s (± 3.02%)}	_{2.65s (± 3.84%)}	_~	_2.58s	_2.84s	_{p=0.936 n=6}
_{Total Time}	_{43.37s (± 0.69%)}	_{43.48s (± 0.26%)}	_~	_43.31s	_43.61s	_{p=0.297 n=6}
_{self-build-src-public-api - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_1,221,221	_1,221,264	_{+43 (+ 0.00%)}	_~	_~	_{p=0.001 n=6}
_Types	_259,523	_259,540	_{+17 (+ 0.01%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{2,414,011k (± 0.03%)}	_{2,413,361k (± 0.02%)}	_~	_2,412,776k	_2,413,868k	_{p=0.128 n=6}
_{Parse Time}	_{6.26s (± 0.82%)}	_{6.28s (± 1.55%)}	_~	_6.15s	_6.42s	_{p=0.936 n=6}
_{Bind Time}	_{2.04s (± 1.30%)}	_{2.04s (± 0.62%)}	_~	_2.02s	_2.05s	_{p=1.000 n=6}
_{Check Time}	_{40.27s (± 0.21%)}	_{40.31s (± 0.15%)}	_~	_40.20s	_40.37s	_{p=0.518 n=6}
_{Emit Time}	_{3.11s (± 2.72%)}	_{3.16s (± 3.29%)}	_~	_3.04s	_3.27s	_{p=0.423 n=6}
_{Total Time}	_{51.71s (± 0.23%)}	_{51.80s (± 0.32%)}	_~	_51.54s	_51.96s	_{p=0.378 n=6}
_{self-compiler - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_256,767	_256,809	_{+42 (+ 0.02%)}	_~	_~	_{p=0.001 n=6}
_Types	_104,587	_104,601	_{+14 (+ 0.01%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{426,112k (± 0.01%)}	_{426,185k (± 0.01%)}	_{+73k (+ 0.02%)}	_426,109k	_426,238k	_{p=0.045 n=6}
_{Parse Time}	_{3.36s (± 0.62%)}	_{3.35s (± 0.48%)}	_~	_3.33s	_3.37s	_{p=0.465 n=6}
_{Bind Time}	_{1.31s (± 0.62%)}	_{1.32s (± 0.62%)}	_~	_1.31s	_1.33s	_{p=0.666 n=6}
_{Check Time}	_{17.84s (± 0.31%)}	_{17.89s (± 0.34%)}	_~	_17.82s	_17.98s	_{p=0.147 n=6}
_{Emit Time}	_{1.38s (± 1.61%)}	_{1.36s (± 1.57%)}	_~	_1.33s	_1.38s	_{p=0.072 n=6}
_{Total Time}	_{23.89s (± 0.19%)}	_{23.91s (± 0.29%)}	_~	_23.81s	_23.99s	_{p=0.687 n=6}
_{ts-pre-modules - node (v18.15.0, x64)}
_Errors	₃₅	₃₅	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_224,575	_224,583	_{+8 (+ 0.00%)}	_~	_~	_{p=0.001 n=6}
_Types	_93,785	_93,791	_{+6 (+ 0.01%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{369,897k (± 0.03%)}	_{369,921k (± 0.02%)}	_~	_369,780k	_370,041k	_{p=1.000 n=6}
_{Parse Time}	_{3.52s (± 0.66%)}	_{3.50s (± 1.12%)}	_~	_3.44s	_3.56s	_{p=0.376 n=6}
_{Bind Time}	_{1.93s (± 0.89%)}	_{1.95s (± 1.10%)}	_~	_1.93s	_1.98s	_{p=0.163 n=6}
_{Check Time}	_{19.40s (± 0.29%)}	_{19.36s (± 0.41%)}	_~	_19.25s	_19.47s	_{p=0.688 n=6}
_{Emit Time}	_0.00s	_0.00s	_~	_~	_~	_{p=1.000 n=6}
_{Total Time}	_{24.85s (± 0.26%)}	_{24.81s (± 0.39%)}	_~	_24.66s	_24.92s	_{p=0.518 n=6}
_{vscode - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_2,823,941	_2,823,942	_{+1 (+ 0.00%)}	_~	_~	_{p=0.001 n=6}
_Types	_957,912	_957,912	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{2,996,285k (± 0.00%)}	_{2,996,309k (± 0.00%)}	_~	_2,996,200k	_2,996,378k	_{p=0.298 n=6}
_{Parse Time}	_{17.02s (± 0.39%)}	_{16.98s (± 0.22%)}	_~	_16.93s	_17.04s	_{p=0.223 n=6}
_{Bind Time}	_{5.04s (± 0.29%)}	_{5.04s (± 0.27%)}	_~	_5.02s	_5.05s	_{p=0.933 n=6}
_{Check Time}	_{89.44s (± 0.22%)}	_{89.28s (± 0.35%)}	_~	_88.92s	_89.84s	_{p=0.229 n=6}
_{Emit Time}	_{28.83s (± 0.59%)}	_{28.77s (± 0.40%)}	_~	_28.59s	_28.88s	_{p=0.810 n=6}
_{Total Time}	_{140.33s (± 0.25%)}	_{140.06s (± 0.22%)}	_~	_139.76s	_140.66s	_{p=0.128 n=6}
_{webpack - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_265,866	_265,866	_~	_~	_~	_{p=1.000 n=6}
_Types	_108,401	_108,401	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{410,516k (± 0.01%)}	_{410,529k (± 0.02%)}	_~	_410,484k	_410,672k	_{p=0.810 n=6}
_{Parse Time}	_{3.84s (± 1.36%)}	_{3.82s (± 0.85%)}	_~	_3.79s	_3.87s	_{p=0.870 n=6}
_{Bind Time}	_{1.67s (± 0.83%)}	_{1.66s (± 0.31%)}	_~	_1.66s	_1.67s	_{p=0.928 n=6}
_{Check Time}	_{16.93s (± 0.20%)}	_{16.95s (± 0.29%)}	_~	_16.90s	_17.01s	_{p=0.572 n=6}
_{Emit Time}	_0.00s	_0.00s	_~	_~	_~	_{p=1.000 n=6}
_{Total Time}	_{22.44s (± 0.35%)}	_{22.44s (± 0.30%)}	_~	_22.34s	_22.54s	_{p=0.936 n=6}
_{xstate-main - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_524,639	_524,639	_~	_~	_~	_{p=1.000 n=6}
_Types	_178,906	_178,906	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{462,680k (± 0.03%)}	_{462,702k (± 0.01%)}	_~	_462,612k	_462,808k	_{p=0.423 n=6}
_{Parse Time}	_{3.12s (± 0.24%)}	_{3.11s (± 0.55%)}	_~	_3.08s	_3.13s	_{p=0.280 n=6}
_{Bind Time}	_{1.17s (± 0.76%)}	_{1.16s (± 0.54%)}	_~	_1.15s	_1.17s	_{p=0.070 n=6}
_{Check Time}	_{18.21s (± 0.85%)}	_{18.33s (± 0.21%)}	_~	_18.29s	_18.40s	_{p=0.296 n=6}
_{Emit Time}	_{0.00s (±154.76%)}	_0.00s	_~	_~	_~	_{p=0.174 n=6}
_{Total Time}	_{22.50s (± 0.68%)}	_{22.60s (± 0.21%)}	_~	_22.54s	_22.67s	_{p=0.419 n=6}

System info unknown

Hosts

node (v18.15.0, x64)

Scenarios

Compiler-Unions - node (v18.15.0, x64)
angular-1 - node (v18.15.0, x64)
mui-docs - node (v18.15.0, x64)
self-build-src - node (v18.15.0, x64)
self-build-src-public-api - node (v18.15.0, x64)
self-compiler - node (v18.15.0, x64)
ts-pre-modules - node (v18.15.0, x64)
vscode - node (v18.15.0, x64)
webpack - node (v18.15.0, x64)
xstate-main - node (v18.15.0, x64)

_Benchmark	_Name	_Iterations
_Current	_pr	₆
_Baseline	_baseline	₆

Developer Information:

Download Benchmarks

TypeScript Bot (typescript-bot) · 2024-05-15T22:42:05Z

Jake Bailey (@jakebailey) Here are the results of running the top 400 repos comparing main and refs/pull/58495/merge:

Everything looks good!

David Greenspan (dgreensp) · 2024-10-11T01:41:47Z

This is incredible work! Hope to see it land :)

Am I correct that this allows a function to assert things about multiple parameters?

Andrii Oriekhov (andriyor) · 2026-02-25T19:21:32Z

Is there any chance it will be merged?

TypeScript Bot (typescript-bot) · 2026-03-24T21:19:08Z

With 6.0 out as the final release vehicle for this codebase, we're closing all PRs that don't fit the merge criteria for post-6.0 patches. If you think this was a mistake and this PR fits the post-6.0 patch criteria, please post to the 6.0 iteration issue with details (specifically, which PR and which patch criteria it satisfies).

Next steps for PRs:

For crash bugfixes or language service improvements, PRs are currently accepted at the typescript-go repo
Changes to type system behavior should wait until after 7.0, at which point mainline TypeScript development will resume in this repository with the Go codebase
Library file updates (lib.d.ts etc) continue to live in this repo or the DOM Generator repo as appropriate

Infer AssertsIdentifier type predicates
257abf6

TypeScript Bot (typescript-bot) added the For Uncommitted Bug PR for untriaged, rejected, closed or missing bug label May 10, 2024

Dan Vanderkam (danvk) commented May 10, 2024
View reviewed changes

a few more tests
f894588

Dan Vanderkam (danvk) added 5 commits May 12, 2024 09:54

do not run on arrow functions
03ce90f

exclude methods as well
6214e93

new tests and baselines
7b62271

more tests, fix bug with any
06426aa

accept baselines
4f8c044

Dan Vanderkam (danvk) mentioned this pull request May 13, 2024
Narrowing by type predicate fails to produce intersection type with weak type #58518
Open

remove irrelevant tests
16a42f3

Dan Vanderkam (danvk) added 2 commits May 15, 2024 09:01

accept error baseline
b242dbd

exclude funtion expressions + accept baselines
7f8343a

Dan Vanderkam (danvk) marked this pull request as ready for review May 15, 2024 13:38

Dan Vanderkam (danvk) mentioned this pull request May 15, 2024
Type predicate assertion does not carry over when used in another function #51326
Closed

Dan Vanderkam (danvk) mentioned this pull request May 15, 2024
Infer type predicates from function bodies using control flow analysis #57465
Merged

Merge branch 'main' into infer-assertions
d990b14

TypeScript Bot (typescript-bot) closed this Mar 24, 2026

coderabbitaiBot mentioned this pull request Apr 10, 2026
Add check blocks, entailment verification, and improved guard extraction subsetpark/pantagruel#77
Merged
5 tasks

Dhruv Sharma (Dhruv2mars) mentioned this pull request Jul 10, 2026
Narrowing by type predicate fails to produce intersection type with weak type Dhruv2mars/typescript-relunar-testbed#4160
Open

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/mnt/ts_downloads/_/m/minimatch/tsconfig.json

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