Update LKG to enable improved narrowing in 4.4. #44842
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| ); | ||
| const expr = some(pendingExpressions) ? | ||
| factory.inlineExpressions(compact([...pendingExpressions!, node])) : | ||
| factory.inlineExpressions(compact([...pendingExpressions, node])) : |
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This one is actually unfortunate - pendingExpressions is actually typed as never because we have an earlier assignment of undefined followed by a check for some(...) which is a type predicate on readonly T[]. Since you can't narrow down a readonly T[] from an undefined, it leaves us with never.
The real culprit is #9998, but it is also strange that we just allow a spread of type never.
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I did notice one opportunity for a new narrowing: accessing a property on a non-null value. When you write if (foo!.bar) {
// ...
}You shouldn't have to repeat the if (foo!.bar) {
foo.bar.baz()
}I think the only downside is that it's sometimes nice to ensure all uses of a variable look similar. |
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How did you find all the places to remove !? Did the linter point them out for you?
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At first it was manual just to get a sense of some patterns it would/wouldn't catch, but then yes, I ran |
| "hashchange": HashChangeEvent; | ||
| "gamepadconnected": Event; | ||
| "gamepaddisconnected": Event; | ||
| "hashchange": Event; |
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Why this is changed to Evnet from HashChangeEvent?
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These are auto-generated, so they might need to be fixed up. Maybe @saschanaz or @orta have more context here.
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This got added back: microsoft/TypeScript-DOM-lib-generator#1104
| interface SVGElementInstance extends EventTarget { | ||
| readonly correspondingElement: SVGElement; | ||
| readonly correspondingUseElement: SVGUseElement; | ||
| } |
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These properties used to be available on SVGElement, which used to extend SVGElementInstance in LOC 12903. They disappeared during the upgrade from v4.3.5 to v4.4.2.
Reported here: microsoft/TypeScript-DOM-lib-generator#1023 (comment)
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Removal was intentional, as per microsoft/TypeScript-DOM-lib-generator#1023 (comment):
Those are not available on any modern browser nor MDN, and thus are probably IE-specific properties. The removal is intended since the types library intends to only include things that exist in modern browsers.
Fixes #44841.