Infer type predicates for functions with multiple returns by danvk · Pull Request #58154 · microsoft/TypeScript

Dan Vanderkam (danvk) · 2024-04-11T21:42:19Z

Follow-on to #57465

The original PR restricted itself to functions with a single return. This PR lifts that restriction.

This allows us to infer predicates for constructs like this:

// infers x is string | DatefunctionifElseIfPredicate(x: string|number|Date){if(typeofx==='string'){returntrue;}elseif(xinstanceofDate){returntrue;}returnfalse;}

or

// infers str is "a" | "b" | "c"functionswitchPredicate(str: string){switch(str){case'a':
case'b':
case'c':
returntruedefault:
returnfalse}}

How this works

Type predicate inference works by rewriting return statements from:

functionfoo(p: InitType){returnexpr_involving_p;}

to:

functionfoo(p: InitType){if(expr_involving_p){p// TrueType}else{p// FalseType}}

If TrueType != InitType then we have a candidate for a type predicate. To generalize this to multiple returns, we determine the TrueType at each return statement and union them. These are all the parameter types for which the function can return true.

To verify the "if and only if" semantics of type predicates, we feed the type predicate type back into the function and look at all the false cases. For a valid type predicate, these should all be never.

I've also special-cased return true and return false. These weren't especially relevant when getTypePredicateFromBody only allowed one return, but they're very relevant now.

Why this might be a good idea

Like #57465, this should only produce valid type predicates, which should result in more precise types.

This makes inferred type predicates less sensitive to seemingly irrelevant refactors, such as:

// may have an inferred type predicatefunctionf1(arg){returncond1(arg)&&cond2(arg);}// cannot have an inferred type predicate in TS 5.5functionf1(arg){if(!cond1(arg))returnfalse;returncond2(arg);}

These kinds of refactors don't affect inferred return types, so it may be surprising that they affect inferred type predicates.

While this does result in predicate inference running on more functions, the perf impact seems to be minimal.

Why this might not be a good idea

Multi-return type predicates are not as common as single-return type predicates:

There were only two functions in the existing baselines that became type predicates with this change.
There were three inferred type predicates in TypeScript itself, and another three across the top400 suite. See Experiment: report functions with multiple returns that could be type predicates #58173 and Infer type predicates for functions with multiple returns #58154 (comment).

So the impact will be relatively small compared to the original change.

This does make the type predicate inference code a bit harder to follow since we're always working with Type[] instead of Type.

Moreover, I got a new circularity error in emitter.ts. This would also have been a new circularity error with #57465, but the type predicate inference code didn't run because one of the functions had two returns. This change increases the odds that this happens on existing code. This error no longer happens.

Jake Bailey (jakebailey) · 2024-04-11T21:44:47Z

TypeScript Bot (@typescript-bot) test it

TypeScript Bot (typescript-bot) · 2024-04-11T21:44:54Z

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

TypeScript Bot (typescript-bot) · 2024-04-11T22:07:02Z

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) · 2024-04-11T22:12:02Z

Jake Bailey (@jakebailey) Here are the results of running the user tests comparing main and refs/pull/58154/merge:

Everything looks good!

TypeScript Bot (typescript-bot) · 2024-04-11T22:21:00Z

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
_{Angular - node (v18.15.0, x64)}
_{Memory used}	_{295,945k (± 0.01%)}	_{295,933k (± 0.01%)}	_~	_295,885k	_295,972k	_{p=0.630 n=6}
_{Parse Time}	_{2.65s (± 0.51%)}	_{2.66s (± 0.51%)}	_~	_2.63s	_2.67s	_{p=0.547 n=6}
_{Bind Time}	_{0.82s (± 1.62%)}	_{0.82s (± 1.33%)}	_~	_0.81s	_0.83s	_{p=0.859 n=6}
_{Check Time}	_{8.23s (± 0.27%)}	_{8.25s (± 0.25%)}	_~	_8.21s	_8.27s	_{p=0.517 n=6}
_{Emit Time}	_{7.05s (± 0.15%)}	_{7.05s (± 0.22%)}	_~	_7.03s	_7.07s	_{p=0.218 n=6}
_{Total Time}	_{18.77s (± 0.08%)}	_{18.77s (± 0.20%)}	_~	_18.73s	_18.83s	_{p=0.511 n=6}
_{Compiler-Unions - node (v18.15.0, x64)}
_{Memory used}	_{191,643k (± 0.02%)}	_{194,175k (± 0.92%)}	_{+2,532k (+ 1.32%)}	_191,823k	_195,435k	_{p=0.005 n=6}
_{Parse Time}	_{1.35s (± 0.62%)}	_{1.37s (± 1.00%)}	_~	_1.35s	_1.39s	_{p=0.109 n=6}
_{Bind Time}	_{0.72s (± 0.57%)}	_{0.72s (± 0.00%)}	_~	_0.72s	_0.72s	_{p=0.405 n=6}
_{Check Time}	_{9.43s (± 0.25%)}	_{9.45s (± 0.71%)}	_~	_9.38s	_9.54s	_{p=0.748 n=6}
_{Emit Time}	_{2.61s (± 1.16%)}	_{2.62s (± 1.20%)}	_~	_2.56s	_2.64s	_{p=0.685 n=6}
_{Total Time}	_{14.11s (± 0.29%)}	_{14.15s (± 0.54%)}	_~	_14.09s	_14.26s	_{p=0.520 n=6}
_{Monaco - node (v18.15.0, x64)}
_{Memory used}	_{347,723k (± 0.01%)}	_{347,734k (± 0.00%)}	_~	_347,723k	_347,749k	_{p=0.630 n=6}
_{Parse Time}	_{2.48s (± 0.59%)}	_{2.48s (± 0.54%)}	_~	_2.46s	_2.50s	_{p=1.000 n=6}
_{Bind Time}	_{0.89s (± 0.58%)}	_{0.89s (± 0.91%)}	_~	_0.89s	_0.91s	_{p=0.114 n=6}
_{Check Time}	_{6.97s (± 0.51%)}	_{6.96s (± 0.17%)}	_~	_6.95s	_6.98s	_{p=0.871 n=6}
_{Emit Time}	_{4.07s (± 0.36%)}	_{4.07s (± 0.25%)}	_~	_4.06s	_4.08s	_{p=0.530 n=6}
_{Total Time}	_{14.41s (± 0.16%)}	_{14.42s (± 0.19%)}	_~	_14.38s	_14.46s	_{p=0.808 n=6}
_{TFS - node (v18.15.0, x64)}
_{Memory used}	_{302,608k (± 0.01%)}	_{302,608k (± 0.01%)}	_~	_302,585k	_302,652k	_{p=0.810 n=6}
_{Parse Time}	_{2.39s (± 0.97%)}	_{2.41s (± 0.59%)}	_~	_2.39s	_2.43s	_{p=0.075 n=6}
_{Bind Time}	_{1.16s (± 0.35%)}	_{1.16s (± 0.35%)}	_~	_1.16s	_1.17s	_{p=0.218 n=6}
_{Check Time}	_{7.45s (± 0.31%)}	_{7.46s (± 0.49%)}	_~	_7.40s	_7.50s	_{p=0.331 n=6}
_{Emit Time}	_{4.27s (± 0.58%)}	_{4.27s (± 0.75%)}	_~	_4.23s	_4.32s	_{p=0.684 n=6}
_{Total Time}	_{15.27s (± 0.26%)}	_{15.31s (± 0.36%)}	_~	_15.24s	_15.36s	_{p=0.260 n=6}
_{material-ui - node (v18.15.0, x64)}
_{Memory used}	_{510,584k (± 0.01%)}	_{510,609k (± 0.01%)}	_~	_510,579k	_510,651k	_{p=0.128 n=6}
_{Parse Time}	_{2.66s (± 0.51%)}	_{2.67s (± 0.76%)}	_~	_2.64s	_2.70s	_{p=0.164 n=6}
_{Bind Time}	_{0.98s (± 1.58%)}	_{0.99s (± 0.83%)}	_~	_0.98s	_1.00s	_{p=0.510 n=6}
_{Check Time}	_{17.20s (± 0.28%)}	_{17.21s (± 0.31%)}	_~	_17.11s	_17.25s	_{p=0.288 n=6}
_{Emit Time}	_{0.00s (± 0.00%)}	_{0.00s (± 0.00%)}	_~	_0.00s	_0.00s	_{p=1.000 n=6}
_{Total Time}	_{20.84s (± 0.21%)}	_{20.88s (± 0.29%)}	_~	_20.77s	_20.93s	_{p=0.226 n=6}
_{mui-docs - node (v18.15.0, x64)}
_{Memory used}	_{1,742,692k (± 0.00%)}	_{1,742,670k (± 0.00%)}	_~	_1,742,605k	_1,742,747k	_{p=0.261 n=6}
_{Parse Time}	_{7.85s (± 0.51%)}	_{7.85s (± 0.78%)}	_~	_7.79s	_7.96s	_{p=0.808 n=6}
_{Bind Time}	_{2.74s (± 0.89%)}	_{2.75s (± 0.87%)}	_~	_2.71s	_2.78s	_{p=0.566 n=6}
_{Check Time}	_{66.40s (± 0.38%)}	_{66.40s (± 0.47%)}	_~	_65.87s	_66.75s	_{p=0.872 n=6}
_{Emit Time}	_{0.16s (± 0.00%)}	_{0.16s (± 3.29%)}	_~	_0.15s	_0.16s	_{p=0.174 n=6}
_{Total Time}	_{77.15s (± 0.34%)}	_{77.16s (± 0.38%)}	_~	_76.62s	_77.49s	_{p=0.936 n=6}
_{self-build-src - node (v18.15.0, x64)}
_{Memory used}	_{2,303,056k (± 0.04%)}	_{2,302,781k (± 0.02%)}	_~	_2,302,126k	_2,303,189k	_{p=1.000 n=6}
_{Parse Time}	_{7.38s (± 0.63%)}	_{7.37s (± 1.18%)}	_~	_7.29s	_7.53s	_{p=0.575 n=6}
_{Bind Time}	_{2.76s (± 0.58%)}	_{2.73s (± 0.88%)}	_~	_2.71s	_2.77s	_{p=0.065 n=6}
_{Check Time}	_{48.73s (± 0.41%)}	_{48.91s (± 0.72%)}	_~	_48.44s	_49.48s	_{p=0.471 n=6}
_{Emit Time}	_{3.88s (± 2.57%)}	_{3.86s (± 3.57%)}	_~	_3.72s	_4.12s	_{p=0.689 n=6}
_{Total Time}	_{62.75s (± 0.38%)}	_{62.90s (± 0.66%)}	_~	_62.41s	_63.62s	_{p=0.520 n=6}
_{self-build-src-public-api - node (v18.15.0, x64)}
_{Memory used}	_{2,377,109k (± 0.03%)}	_{2,377,257k (± 0.03%)}	_~	_2,376,567k	_2,378,563k	_{p=0.936 n=6}
_{Parse Time}	_{7.65s (± 1.03%)}	_{7.65s (± 0.81%)}	_~	_7.54s	_7.72s	_{p=0.810 n=6}
_{Bind Time}	_{2.50s (± 0.89%)}	_{2.48s (± 0.49%)}	_~	_2.47s	_2.50s	_{p=0.171 n=6}
_{Check Time}	_{49.30s (± 0.14%)}	_{49.23s (± 0.37%)}	_~	_49.01s	_49.46s	_{p=0.810 n=6}
_{Emit Time}	_{3.91s (± 3.34%)}	_{3.94s (± 1.93%)}	_~	_3.86s	_4.07s	_{p=0.873 n=6}
_{Total Time}	_{63.35s (± 0.22%)}	_{63.33s (± 0.34%)}	_~	_63.12s	_63.68s	_{p=0.936 n=6}
_{self-compiler - node (v18.15.0, x64)}
_{Memory used}	_{418,399k (± 0.01%)}	_{418,502k (± 0.01%)}	_{+102k (+ 0.02%)}	_418,447k	_418,549k	_{p=0.005 n=6}
_{Parse Time}	_{4.18s (± 0.41%)}	_{4.18s (± 0.33%)}	_~	_4.16s	_4.20s	_{p=0.742 n=6}
_{Bind Time}	_{1.59s (± 2.71%)}	_{1.58s (± 0.57%)}	_~	_1.57s	_1.59s	_{p=1.000 n=6}
_{Check Time}	_{22.05s (± 0.25%)}	_{22.08s (± 0.35%)}	_~	_21.97s	_22.20s	_{p=0.470 n=6}
_{Emit Time}	_{1.69s (± 1.10%)}	_{1.70s (± 1.25%)}	_~	_1.66s	_1.72s	_{p=0.278 n=6}
_{Total Time}	_{29.51s (± 0.29%)}	_{29.54s (± 0.30%)}	_~	_29.44s	_29.71s	_{p=0.470 n=6}
_{vscode - node (v18.15.0, x64)}
_{Memory used}	_{2,907,545k (± 0.00%)}	_{2,907,535k (± 0.00%)}	_~	_2,907,468k	_2,907,596k	_{p=0.689 n=6}
_{Parse Time}	_{15.93s (± 0.26%)}	_{15.99s (± 0.47%)}	_~	_15.92s	_16.13s	_{p=0.077 n=6}
_{Bind Time}	_{4.91s (± 0.47%)}	_{4.91s (± 0.38%)}	_~	_4.88s	_4.93s	_{p=0.628 n=6}
_{Check Time}	_{86.42s (± 0.27%)}	_{85.99s (± 0.26%)}	_{-0.43s (- 0.50%)}	_85.71s	_86.39s	_{p=0.020 n=6}
_{Emit Time}	_{23.62s (± 0.49%)}	_{23.55s (± 0.62%)}	_~	_23.31s	_23.72s	_{p=0.748 n=6}
_{Total Time}	_{130.88s (± 0.20%)}	_{130.44s (± 0.25%)}	_{-0.44s (- 0.34%)}	_129.89s	_130.84s	_{p=0.031 n=6}
_{webpack - node (v18.15.0, x64)}
_{Memory used}	_{408,686k (± 0.01%)}	_{408,690k (± 0.01%)}	_~	_408,646k	_408,774k	_{p=0.748 n=6}
_{Parse Time}	_{3.87s (± 0.72%)}	_{3.86s (± 0.48%)}	_~	_3.85s	_3.90s	_{p=0.870 n=6}
_{Bind Time}	_{1.67s (± 1.05%)}	_{1.66s (± 0.93%)}	_~	_1.63s	_1.67s	_{p=0.618 n=6}
_{Check Time}	_{16.73s (± 0.30%)}	_{16.71s (± 0.29%)}	_~	_16.64s	_16.78s	_{p=0.298 n=6}
_{Emit Time}	_{0.00s (± 0.00%)}	_{0.00s (± 0.00%)}	_~	_0.00s	_0.00s	_{p=1.000 n=6}
_{Total Time}	_{22.27s (± 0.37%)}	_{22.23s (± 0.27%)}	_~	_22.17s	_22.31s	_{p=0.521 n=6}
_{xstate - node (v18.15.0, x64)}
_{Memory used}	_{670,847k (± 0.02%)}	_{670,841k (± 0.01%)}	_~	_670,735k	_670,942k	_{p=1.000 n=6}
_{Parse Time}	_{4.98s (± 0.35%)}	_{4.98s (± 0.68%)}	_~	_4.95s	_5.03s	_{p=0.520 n=6}
_{Bind Time}	_{2.32s (± 0.76%)}	_{2.32s (± 0.85%)}	_~	_2.30s	_2.35s	_{p=0.870 n=6}
_{Check Time}	_{4.20s (± 0.79%)}	_{4.24s (± 1.48%)}	_~	_4.15s	_4.31s	_{p=0.295 n=6}
_{Emit Time}	_{0.03s (± 0.00%)}	_{0.03s (± 0.00%)}	_~	_0.03s	_0.03s	_{p=1.000 n=6}
_{Total Time}	_{11.54s (± 0.48%)}	_{11.58s (± 0.79%)}	_~	_11.45s	_11.71s	_{p=0.419 n=6}

System info unknown

Hosts

node (v18.15.0, x64)

Scenarios

Angular - node (v18.15.0, x64)
Compiler-Unions - node (v18.15.0, x64)
Monaco - node (v18.15.0, x64)
TFS - node (v18.15.0, x64)
material-ui - 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)
vscode - node (v18.15.0, x64)
webpack - node (v18.15.0, x64)
xstate - node (v18.15.0, x64)

_Benchmark	_Name	_Iterations
_Current	_pr	₆
_Baseline	_baseline	₆

Developer Information:

Download Benchmarks

TypeScript Bot (typescript-bot) · 2024-04-11T23:33:05Z

Jake Bailey (@jakebailey) Here are the results of running the top 400 repos comparing main and refs/pull/58154/merge:

Everything looks good!

Dan Vanderkam (danvk) · 2024-04-12T13:44:18Z

👀 So minimal perf impact and no breaks beyond the self-check circularity issue. Maybe this is a good idea? 🤔

Jake Bailey (jakebailey) · 2024-04-12T14:54:41Z

TypeScript Bot (@typescript-bot) test top800

TypeScript Bot (typescript-bot) · 2024-04-12T14:54:46Z

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

Command	Status	Results
`test top800`	✅ Started	✅ Results

TypeScript Bot (typescript-bot) · 2024-04-12T17:31:45Z

Jake Bailey (@jakebailey) Here are the results of running the top 800 repos comparing main and refs/pull/58154/merge:

Everything looks good!

Dan Vanderkam (danvk) · 2024-04-12T21:35:18Z

I put up #58173, which reports an error whenever it infers a type predicate for a function with multiple return statements. That should clarify how common this pattern is in the wild.

Dan Vanderkam (danvk) · 2024-04-12T23:51:22Z

Results of the experiment:

three new type predicates in TypeScript itself, one of which had an impact
one new type predicate in pyright
three new type predicates in the top400 suite

So not many functions match this pattern in the wild, but a few do and there's also not a big perf impact. Up to TS team whether this is a helpful generalization. See Jake Bailey (@jakebailey)'s comment #58173 (comment)

Andreas Källberg (anka-213) · 2024-04-29T14:15:32Z

I would love to have this, since it allows splitting up type predicates instead of having to write them as a single long expression. I'm surprised that things like

functionisArrayOfStrings(x: unknown): x is string[]{if(!xinstanceofArray)returnfalse;returnx.every((y)=>typeofy==='string');}

didn't occur more in your experiment, since I've seen it pretty often for more complicated type predicates.

Dan Vanderkam (danvk) · 2024-04-29T20:31:53Z

Andreas Källberg (@anka-213) if there are examples in the wild that you can point to, that would be helpful. This makes me realize that my experiment (#58173) would not tell us about existing type predicates with 2+ returns, since the predicate inference code doesn't run if there's an explicit return type annotation. In other words, it would not have detected your isArrayOfStrings function. Finding functions like this would be another interesting data point.

FWIW you can break up the long expression by factoring out a variable, you just can't break up the control flow:

// function isArrayOfStrings(x: unknown): x is string[]functionisArrayOfStrings(x: unknown){constisArray=Array.isArray(x);returnisArray&&(x.every((y)=>typeofy==='string'));}

playground

TypeScript Bot (typescript-bot) · 2024-07-11T19:23:54Z

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

Dan Vanderkam (danvk) · 2024-07-11T19:29:05Z

I've merged upstream changes and brought the implementation more in line with main to reduce the diff. I've also updated the PR description in light of the experiments and performance numbers from April. Jake Bailey (@jakebailey) it would be interesting to get new performance numbers to see if the "minimal impact" holds up.

I can open an issue like typescript-bot suggests if that would be a more appropriate way to discuss the merits of this extension.

Jake Bailey (jakebailey) · 2024-07-11T19:30:37Z

TypeScript Bot (@typescript-bot) test it

TypeScript Bot (typescript-bot) · 2024-07-11T19:30:41Z

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

TypeScript Bot (typescript-bot) · 2024-07-11T19:51:28Z

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) · 2024-07-11T19:58:02Z

Jake Bailey (@jakebailey) Here are the results of running the user tests with tsc comparing main and refs/pull/58154/merge:

Everything looks good!

TypeScript Bot (typescript-bot) · 2024-07-11T20:13:28Z

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	_62,153	_62,209	_{+56 (+ 0.09%)}	_~	_~	_{p=0.001 n=6}
_Types	_50,242	_50,258	_{+16 (+ 0.03%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{193,995k (± 0.97%)}	_{192,611k (± 0.82%)}	_~	_191,875k	_195,832k	_{p=0.066 n=6}
_{Parse Time}	_{1.30s (± 0.63%)}	_{1.30s (± 0.31%)}	_~	_1.30s	_1.31s	_{p=0.584 n=6}
_{Bind Time}	_0.71s	_0.71s	_~	_~	_~	_{p=1.000 n=6}
_{Check Time}	_{9.48s (± 0.76%)}	_{9.48s (± 0.42%)}	_~	_9.43s	_9.55s	_{p=1.000 n=6}
_{Emit Time}	_{2.76s (± 0.48%)}	_{2.97s (± 0.97%)}	_{🔻+0.21s (+ 7.67%)}	_2.93s	_3.00s	_{p=0.005 n=6}
_{Total Time}	_{14.26s (± 0.51%)}	_{14.46s (± 0.40%)}	_{+0.21s (+ 1.46%)}	_14.39s	_14.56s	_{p=0.005 n=6}
_{angular-1 - node (v18.15.0, x64)}
_Errors	₅	₅	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_944,114	_944,114	_~	_~	_~	_{p=1.000 n=6}
_Types	_407,050	_407,050	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{1,218,405k (± 0.00%)}	_{1,218,378k (± 0.01%)}	_~	_1,218,270k	_1,218,499k	_{p=0.378 n=6}
_{Parse Time}	_{6.69s (± 0.57%)}	_{6.73s (± 0.77%)}	_~	_6.66s	_6.82s	_{p=0.418 n=6}
_{Bind Time}	_{1.88s (± 0.67%)}	_{1.88s (± 0.43%)}	_~	_1.87s	_1.89s	_{p=0.558 n=6}
_{Check Time}	_{30.61s (± 0.24%)}	_{30.71s (± 0.49%)}	_~	_30.53s	_30.89s	_{p=0.295 n=6}
_{Emit Time}	_{13.59s (± 0.91%)}	_{13.60s (± 0.42%)}	_~	_13.55s	_13.68s	_{p=0.686 n=6}
_{Total Time}	_{52.78s (± 0.36%)}	_{52.91s (± 0.40%)}	_~	_52.69s	_53.28s	_{p=0.378 n=6}
_{mui-docs - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_2,130,296	_2,130,291	_{-5 (- 0.00%)}	_~	_~	_{p=0.001 n=6}
_Types	_927,656	_927,643	_{-13 (- 0.00%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{2,107,060k (± 0.01%)}	_{2,107,028k (± 0.00%)}	_~	_2,106,977k	_2,107,102k	_{p=0.810 n=6}
_{Parse Time}	_{6.62s (± 0.30%)}	_{6.61s (± 0.23%)}	_~	_6.59s	_6.63s	_{p=1.000 n=6}
_{Bind Time}	_{2.33s (± 0.70%)}	_{2.32s (± 0.47%)}	_~	_2.30s	_2.33s	_{p=0.622 n=6}
_{Check Time}	_{70.41s (± 0.75%)}	_{70.72s (± 0.40%)}	_~	_70.35s	_71.07s	_{p=0.336 n=6}
_{Emit Time}	_{0.14s (± 2.95%)}	_{0.14s (± 4.51%)}	_~	_0.13s	_0.15s	_{p=0.673 n=6}
_{Total Time}	_{79.49s (± 0.64%)}	_{79.79s (± 0.35%)}	_~	_79.40s	_80.12s	_{p=0.378 n=6}
_{self-build-src - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_1,226,005	_1,226,072	_{+67 (+ 0.01%)}	_~	_~	_{p=0.001 n=6}
_Types	_261,615	_261,670	_{+55 (+ 0.02%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{2,339,381k (± 0.03%)}	_{2,339,575k (± 0.02%)}	_~	_2,339,026k	_2,340,123k	_{p=0.378 n=6}
_{Parse Time}	_{6.06s (± 0.71%)}	_{6.07s (± 1.29%)}	_~	_6.00s	_6.20s	_{p=0.810 n=6}
_{Bind Time}	_{2.24s (± 0.56%)}	_{2.24s (± 0.56%)}	_~	_2.23s	_2.26s	_{p=0.934 n=6}
_{Check Time}	_{40.34s (± 0.27%)}	_{40.19s (± 0.38%)}	_~	_40.01s	_40.40s	_{p=0.128 n=6}
_{Emit Time}	_{3.86s (± 2.14%)}	_{3.85s (± 0.91%)}	_~	_3.78s	_3.87s	_{p=0.936 n=6}
_{Total Time}	_{52.51s (± 0.27%)}	_{52.37s (± 0.30%)}	_~	_52.13s	_52.56s	_{p=0.230 n=6}
_{self-build-src-public-api - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_1,226,005	_1,226,072	_{+67 (+ 0.01%)}	_~	_~	_{p=0.001 n=6}
_Types	_261,615	_261,670	_{+55 (+ 0.02%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{2,413,110k (± 0.02%)}	_{2,413,066k (± 0.02%)}	_~	_2,412,040k	_2,413,566k	_{p=0.471 n=6}
_{Parse Time}	_{5.25s (± 0.55%)}	_{5.24s (± 0.79%)}	_~	_5.19s	_5.31s	_{p=0.575 n=6}
_{Bind Time}	_{1.68s (± 0.50%)}	_{1.69s (± 0.95%)}	_~	_1.67s	_1.71s	_{p=0.667 n=6}
_{Check Time}	_{34.64s (± 0.21%)}	_{34.61s (± 0.12%)}	_~	_34.55s	_34.65s	_{p=0.335 n=6}
_{Emit Time}	_{3.28s (± 1.59%)}	_{3.29s (± 1.16%)}	_~	_3.24s	_3.33s	_{p=0.630 n=6}
_{Total Time}	_{44.87s (± 0.33%)}	_{44.82s (± 0.14%)}	_~	_44.74s	_44.91s	_{p=0.630 n=6}
_{self-compiler - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_258,315	_258,380	_{+65 (+ 0.03%)}	_~	_~	_{p=0.001 n=6}
_Types	_104,817	_104,863	_{+46 (+ 0.04%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{427,248k (± 0.03%)}	_{427,452k (± 0.03%)}	_{+204k (+ 0.05%)}	_427,294k	_427,650k	_{p=0.045 n=6}
_{Parse Time}	_{3.31s (± 0.55%)}	_{3.31s (± 0.52%)}	_~	_3.29s	_3.33s	_{p=0.931 n=6}
_{Bind Time}	_{1.31s (± 1.01%)}	_{1.32s (± 0.93%)}	_~	_1.29s	_1.32s	_{p=0.673 n=6}
_{Check Time}	_{17.81s (± 0.21%)}	_{17.84s (± 0.28%)}	_~	_17.77s	_17.90s	_{p=0.294 n=6}
_{Emit Time}	_{1.65s (± 0.54%)}	_{1.63s (± 0.55%)}	_{-0.02s (- 1.21%)}	_1.62s	_1.64s	_{p=0.011 n=6}
_{Total Time}	_{24.09s (± 0.16%)}	_{24.10s (± 0.29%)}	_~	_24.00s	_24.17s	_{p=0.688 n=6}
_{ts-pre-modules - node (v18.15.0, x64)}
_Errors	₃₅	₃₅	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_224,565	_224,568	_{+3 (+ 0.00%)}	_~	_~	_{p=0.001 n=6}
_Types	_93,734	_93,738	_{+4 (+ 0.00%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{369,536k (± 0.02%)}	_{369,537k (± 0.02%)}	_~	_369,425k	_369,685k	_{p=1.000 n=6}
_{Parse Time}	_{3.42s (± 1.05%)}	_{3.46s (± 1.08%)}	_~	_3.40s	_3.50s	_{p=0.198 n=6}
_{Bind Time}	_{1.94s (± 0.73%)}	_{1.95s (± 0.79%)}	_~	_1.93s	_1.96s	_{p=0.276 n=6}
_{Check Time}	_{19.17s (± 0.38%)}	_{19.19s (± 0.29%)}	_~	_19.15s	_19.30s	_{p=0.630 n=6}
_{Emit Time}	_0.00s	_0.00s	_~	_~	_~	_{p=1.000 n=6}
_{Total Time}	_{24.53s (± 0.34%)}	_{24.59s (± 0.33%)}	_~	_24.49s	_24.72s	_{p=0.335 n=6}
_{vscode - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_2,889,872	_2,889,874	_{+2 (+ 0.00%)}	_~	_~	_{p=0.001 n=6}
_Types	_977,787	_977,791	_{+4 (+ 0.00%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{3,053,447k (± 0.00%)}	_{3,053,475k (± 0.00%)}	_~	_3,053,403k	_3,053,544k	_{p=0.689 n=6}
_{Parse Time}	_{16.90s (± 0.51%)}	_{16.83s (± 0.38%)}	_~	_16.77s	_16.94s	_{p=0.146 n=6}
_{Bind Time}	_{5.12s (± 0.40%)}	_{5.11s (± 0.42%)}	_~	_5.08s	_5.14s	_{p=0.252 n=6}
_{Check Time}	_{91.37s (± 2.95%)}	_{92.13s (± 2.26%)}	_~	_89.55s	_94.56s	_{p=0.575 n=6}
_{Emit Time}	_{27.68s (± 9.12%)}	_{27.10s (± 7.87%)}	_~	_24.40s	_29.46s	_{p=0.689 n=6}
_{Total Time}	_{141.07s (± 0.25%)}	_{141.16s (± 0.37%)}	_~	_140.52s	_142.03s	_{p=0.936 n=6}
_{webpack - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_267,239	_267,239	_~	_~	_~	_{p=1.000 n=6}
_Types	_108,815	_108,815	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{411,833k (± 0.02%)}	_{411,847k (± 0.02%)}	_~	_411,730k	_411,957k	_{p=0.936 n=6}
_{Parse Time}	_{4.73s (± 0.19%)}	_{4.76s (± 0.48%)}	_{+0.03s (+ 0.63%)}	_4.74s	_4.80s	_{p=0.011 n=6}
_{Bind Time}	_{2.08s (± 1.11%)}	_{2.09s (± 0.84%)}	_~	_2.07s	_2.11s	_{p=0.408 n=6}
_{Check Time}	_{20.71s (± 0.41%)}	_{20.74s (± 0.30%)}	_~	_20.68s	_20.82s	_{p=0.470 n=6}
_{Emit Time}	_0.00s	_0.00s	_~	_~	_~	_{p=1.000 n=6}
_{Total Time}	_{27.52s (± 0.34%)}	_{27.60s (± 0.29%)}	_~	_27.50s	_27.71s	_{p=0.228 n=6}
_{xstate-main - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_510,475	_510,475	_~	_~	_~	_{p=1.000 n=6}
_Types	_161,600	_161,600	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{448,046k (± 0.06%)}	_{448,001k (± 0.08%)}	_~	_447,591k	_448,395k	_{p=1.000 n=6}
_{Parse Time}	_{3.14s (± 1.06%)}	_{3.12s (± 0.48%)}	_~	_3.11s	_3.15s	_{p=0.466 n=6}
_{Bind Time}	_{1.17s (± 0.64%)}	_{1.17s (± 0.35%)}	_~	_1.17s	_1.18s	_{p=1.000 n=6}
_{Check Time}	_{16.95s (± 0.58%)}	_{16.99s (± 0.55%)}	_~	_16.86s	_17.13s	_{p=0.520 n=6}
_{Emit Time}	_0.00s	_0.00s	_~	_~	_~	_{p=1.000 n=6}
_{Total Time}	_{21.26s (± 0.50%)}	_{21.28s (± 0.46%)}	_~	_21.15s	_21.44s	_{p=0.688 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) · 2024-07-11T20:54:28Z

Other than the compiler-unions emit time, this looks like ~0 impact. I can take a look at whether there's some giant type predicate being emitted that would account for that, but I'm skeptical since we didn't see change in this number back in April and the behavior of the PR shouldn't be different.

TypeScript Bot (typescript-bot) · 2024-07-11T21:12:21Z

Jake Bailey (@jakebailey) Here are the results of running the top 400 repos with tsc comparing main and refs/pull/58154/merge:

Everything looks good!

TypeScript Bot (typescript-bot) · 2026-03-24T21:19:01Z

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 type predicates with multiple returns
30aef71

TypeScript Bot (typescript-bot) added the For Uncommitted Bug PR for untriaged, rejected, closed or missing bug label Apr 11, 2024

Dan Vanderkam (danvk) mentioned this pull request Apr 12, 2024
Experiment: report functions with multiple returns that could be type predicates #58173
Closed

Dan Vanderkam (danvk) changed the title ~~Experiment: Infer type predicates for functions with multiple returns~~Infer type predicates for functions with multiple returnsMay 15, 2024

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

Dan Vanderkam (danvk) added 4 commits June 28, 2024 14:21

Merge branch 'main' into multi-return-predicate
7afba56

simplify and reduce diff
3311fd0

Add a few more tests
c64d7d0

Merge branch 'main' into multi-return-predicate
79a9dc0

Dan Vanderkam (danvk) marked this pull request as ready for review July 11, 2024 19:23

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

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tsc

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Dan Vanderkam (danvk) commented Apr 11, 2024•
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