Unify substitution type `any` handling into costruction and instantiation #30592

weswigham · 2019-03-26T02:43:09Z

And clean up conditional types a little to match. The changes to conditional resolvedTrueType/resolvedFalseType aren't strictly required, per sey, but they clean up a lot and reduce complexity. We were choosing not to cache types we'd already computed (for no real reason other than a misunderstanding on my part as to when the combinedMapper was used).

Fixing the creation of substitutes to any exposed an issue where we'd generate infinitely expanding types in our infiniteConstraints.ts test (which previously were never expanded because their assignment to a substituted any simply succeeded) - I had to both introduce type-parameter like circularity guards into getConstraintOfType for conditionals and indexed accesses (it was missing them), and further penalize deep instantiations of conditionals within computeBaseConstraint (to capture the exponential explosion of types instantiated by circularly referential conditionals).

Fixes #30569
Fixes #30489

…tion

weswigham · 2019-03-26T03:46:52Z

@typescript-bot test this & @typescript-bot run dt go go go

typescript-bot · 2019-03-26T03:47:17Z

Heya @weswigham, I've started to run the Definitely Typed test suite on this PR at d5f32bd. You can monitor the build here. It should now contribute to this PR's status checks.

typescript-bot · 2019-03-26T03:47:17Z

Heya @weswigham, I've started to run the extended test suite on this PR at d5f32bd. You can monitor the build here. It should now contribute to this PR's status checks.

src/compiler/types.ts

src/compiler/checker.ts

weswigham · 2019-03-26T16:18:21Z

The egg-mock and protractor DT failures are also from master, however the react-redux failure I'll need to look into. It looks like we're assigning something a default inference in a place we don't want to be (or at least weren't before) - will need to check it.

weswigham · 2019-03-26T16:20:43Z

RWC diff is actually nil - test only failed because there's an unaccepted RWC diff on master right now. (Looks like we accepted making the JSON global into a var instead of a const)

weswigham · 2019-03-26T20:12:42Z

Wow, so the react-redux break is indicative of a IIRC known issue in our subtyping rules. (payload: boolean) => { type: string; payload: boolean; } is not seen as a subtype of (...args: any[]) => any), because the parameter any is not a subtype of boolean (just assignable - the position is contravariant, so never is the needed bound there, not unknown). (Thus we produce an intersection and materialize an any in the return position, creating a type with any's in it which passes a following check which it should not) any not behaving as the correct bound for the context it's in for the subtype relation here is painful.

I can definitely special-case the all-any signature inside signaturesRelatedTo such that an any-ish signature has all other signatures as subtypes, but that's only a partial fix (since any in other contravariant positions will still behave undesirably under the subtype relationship).

…rict variance doesnt kill subtyping

weswigham · 2019-03-26T20:21:05Z

@typescript-bot test this & @typescript-bot run dt - I've confirmed react-redux is now clean locally, but let's check the state of the world with the small change to subtyping.

typescript-bot · 2019-03-26T20:21:07Z

Heya @weswigham, I've started to run the extended test suite on this PR at a2fcddc. You can monitor the build here. It should now contribute to this PR's status checks.

typescript-bot · 2019-03-26T20:21:08Z

Heya @weswigham, I've started to run the Definitely Typed test suite on this PR at a2fcddc. You can monitor the build here. It should now contribute to this PR's status checks.

weswigham · 2019-03-26T22:20:23Z

Remaining two DT failures are the two from master - this change is now clean 👍

ahejlsberg · 2019-03-27T17:32:35Z

src/compiler/checker.ts

+         */
+        function isAnySignature(s: Signature) {
+            return !s.typeParameters && (!s.thisParameter || isTypeAny(getTypeOfParameter(s.thisParameter))) && s.parameters.length === 1 &&
+                s.hasRestParameter && getTypeOfParameter(s.parameters[0]) === anyArrayType &&


Also allow for (...args: any) => any.

…nature as well

weswigham · 2019-03-27T17:57:26Z

@ahejlsberg done.

@typescript-bot test this & @typescript-bot run dt because this is an immediately-before-release fix and we like making sure we're not breaking people~

typescript-bot · 2019-03-27T17:57:29Z

Heya @weswigham, I've started to run the extended test suite on this PR at 34cc427. You can monitor the build here. It should now contribute to this PR's status checks.

typescript-bot · 2019-03-27T17:57:29Z

Heya @weswigham, I've started to run the Definitely Typed test suite on this PR at 34cc427. You can monitor the build here. It should now contribute to this PR's status checks.

weswigham · 2019-03-27T19:40:31Z

DT's just as clean as before, this is good. ❤️

@ahejlsberg can you update your review status?

mihailik · 2019-03-28T11:52:06Z

src/compiler/checker.ts

-                    const trueTypeNode = typeToTypeNodeHelper(getTrueTypeFromConditionalType(<ConditionalType>type), context);
-                    const falseTypeNode = typeToTypeNodeHelper(getFalseTypeFromConditionalType(<ConditionalType>type), context);
+                    const trueTypeNode = typeToTypeNodeHelper((<ConditionalType>type).trueType, context);
+                    const falseTypeNode = typeToTypeNodeHelper((<ConditionalType>type).falseType, context);


I thought <angle brackets> casting is meant to be phased out in favour of as casting?

The angle brackets were already here~

weswigham added 2 commits March 25, 2019 19:17

Unify substitution type any handling into costruction and instantia…

cbbbda4

…tion

Strengthen supertype reduction check to reduce breakage

d5f32bd

weswigham requested review from ahejlsberg and RyanCavanaugh March 26, 2019 02:43

ahejlsberg requested changes Mar 26, 2019

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Rename conditional type fields per convention

d28ad01

Explicitly handle anyish signatures in compareSignaturesRelated so st…

73e3733

…rict variance doesnt kill subtyping

weswigham mentioned this pull request Mar 26, 2019

3.4.0-rc - behaviour changed from 3.3 (regression?) #30489

Closed

Merge branch 'master' into unify-substitution-handling

a2fcddc

weswigham requested a review from ahejlsberg March 26, 2019 20:19

ahejlsberg reviewed Mar 27, 2019

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Allow tuple expansions to an any rest to be considered an any sig…

34cc427

…nature as well

RyanCavanaugh merged commit b7881a2 into microsoft:master Mar 27, 2019

weswigham deleted the unify-substitution-handling branch March 27, 2019 19:56

mihailik reviewed Mar 28, 2019

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RyanCavanaugh mentioned this pull request Apr 8, 2019

~50x regression in type instantiation count between 3.3 and 3.4 #30819

Closed

JabX mentioned this pull request Apr 11, 2019

Inference regression with mapped types in 3.4.1 #30868

Closed

amcasey mentioned this pull request Jan 24, 2020

Can the typings be simplified to improve performance? mui/material-ui#19113

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Unify substitution type `any` handling into costruction and instantiation #30592

Unify substitution type `any` handling into costruction and instantiation #30592

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Unify substitution type any handling into costruction and instantiation #30592

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Unify substitution type `any` handling into costruction and instantiation #30592

Unify substitution type `any` handling into costruction and instantiation #30592

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