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Defer resolution of true and false branches in conditional types #31354

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merged 7 commits into from
May 14, 2019
Merged

Defer resolution of true and false branches in conditional types #31354

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71fe8e8
Defer resolution of the true and false branches of conditional types
ahejlsberg May 11, 2019
33c7e7f
Accept new baselines
ahejlsberg May 11, 2019
bb9c5c9
Reuse existing type instantiations
ahejlsberg May 11, 2019
8ba53b6
Simplify conditionals upon comparison, rather than instantiation
weswigham May 13, 2019
4e040f7
Merge pull request #31374 from weswigham/defer-conditionals-with-simp…
ahejlsberg May 13, 2019
1b3589b
Remove simplification logic from getConditionalType + simplify substi…
ahejlsberg May 13, 2019
066e4b6
Accept new baselines
ahejlsberg May 13, 2019
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134 changes: 63 additions & 71 deletions src/compiler/checker.ts
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6 changes: 4 additions & 2 deletions src/compiler/types.ts
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Expand Up @@ -3966,6 +3966,8 @@ namespace ts {
StructuredOrInstantiable = StructuredType | Instantiable,
/* @internal */
ObjectFlagsType = Nullable | Never | Object | Union | Intersection,
/* @internal */
Simplifiable = IndexedAccess | Conditional | Substitution,
// 'Narrowable' types are types where narrowing actually narrows.
// This *should* be every type other than null, undefined, void, and never
Narrowable = Any | Unknown | StructuredOrInstantiable | StringLike | NumberLike | BigIntLike | BooleanLike | ESSymbol | UniqueESSymbol | NonPrimitive,
Expand Down Expand Up @@ -4338,8 +4340,8 @@ namespace ts {
root: ConditionalRoot;
checkType: Type;
extendsType: Type;
trueType: Type;
falseType: Type;
resolvedTrueType: Type;
resolvedFalseType: Type;
/* @internal */
resolvedInferredTrueType?: Type; // The `trueType` instantiated with the `combinedMapper`, if present
/* @internal */
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4 changes: 2 additions & 2 deletions tests/baselines/reference/api/tsserverlibrary.d.ts
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Expand Up @@ -2390,8 +2390,8 @@ declare namespace ts {
root: ConditionalRoot;
checkType: Type;
extendsType: Type;
trueType: Type;
falseType: Type;
resolvedTrueType: Type;
resolvedFalseType: Type;
}
interface SubstitutionType extends InstantiableType {
typeVariable: TypeVariable;
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4 changes: 2 additions & 2 deletions tests/baselines/reference/api/typescript.d.ts
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Expand Up @@ -2390,8 +2390,8 @@ declare namespace ts {
root: ConditionalRoot;
checkType: Type;
extendsType: Type;
trueType: Type;
falseType: Type;
resolvedTrueType: Type;
resolvedFalseType: Type;
}
interface SubstitutionType extends InstantiableType {
typeVariable: TypeVariable;
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76 changes: 44 additions & 32 deletions ...rcularlyConstrainedMappedTypeContainingConditionalNoInfiniteInstantiationDepth.errors.txt
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2 changes: 1 addition & 1 deletion tests/baselines/reference/conditionalTypes1.js
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Expand Up @@ -645,7 +645,7 @@ declare type T82 = Eq2<false, true>;
declare type T83 = Eq2<false, false>;
declare type Foo<T> = T extends string ? boolean : number;
declare type Bar<T> = T extends string ? boolean : number;
declare const convert: <U>(value: Foo<U>) => Foo<U>;
declare const convert: <U>(value: Foo<U>) => Bar<U>;
declare type Baz<T> = Foo<T>;
declare const convert2: <T>(value: Foo<T>) => Foo<T>;
declare function f31<T>(): void;
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6 changes: 3 additions & 3 deletions tests/baselines/reference/conditionalTypes1.types
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Expand Up @@ -779,8 +779,8 @@ type Bar<T> = T extends string ? boolean : number;
>Bar : Bar<T>

const convert = <U>(value: Foo<U>): Bar<U> => value;
>convert : <U>(value: Foo<U>) => Foo<U>
><U>(value: Foo<U>): Bar<U> => value : <U>(value: Foo<U>) => Foo<U>
>convert : <U>(value: Foo<U>) => Bar<U>
><U>(value: Foo<U>): Bar<U> => value : <U>(value: Foo<U>) => Bar<U>
>value : Foo<U>
>value : Foo<U>

Expand Down Expand Up @@ -832,7 +832,7 @@ function f33<T, U>() {
>T1 : Foo<T & U>

type T2 = Bar<T & U>;
>T2 : Foo<T & U>
>T2 : Bar<T & U>

var z: T1;
>z : Foo<T & U>
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28 changes: 14 additions & 14 deletions tests/baselines/reference/conditionalTypes2.errors.txt
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Expand Up @@ -10,13 +10,13 @@ tests/cases/conformance/types/conditional/conditionalTypes2.ts(24,5): error TS23
Type 'keyof B' is not assignable to type 'keyof A'.
Type 'string | number | symbol' is not assignable to type 'keyof A'.
Type 'string' is not assignable to type 'keyof A'.
Type 'string' is not assignable to type 'number | "toString" | "charAt" | "charCodeAt" | "concat" | "indexOf" | "lastIndexOf" | "localeCompare" | "match" | "replace" | "search" | "slice" | "split" | "substring" | "toLowerCase" | "toLocaleLowerCase" | "toUpperCase" | "toLocaleUpperCase" | "trim" | "length" | "substr" | "valueOf"'.
Type 'keyof B' is not assignable to type 'number | "toString" | "charAt" | "charCodeAt" | "concat" | "indexOf" | "lastIndexOf" | "localeCompare" | "match" | "replace" | "search" | "slice" | "split" | "substring" | "toLowerCase" | "toLocaleLowerCase" | "toUpperCase" | "toLocaleUpperCase" | "trim" | "length" | "substr" | "valueOf"'.
Type 'string | number | symbol' is not assignable to type 'number | "toString" | "charAt" | "charCodeAt" | "concat" | "indexOf" | "lastIndexOf" | "localeCompare" | "match" | "replace" | "search" | "slice" | "split" | "substring" | "toLowerCase" | "toLocaleLowerCase" | "toUpperCase" | "toLocaleUpperCase" | "trim" | "length" | "substr" | "valueOf"'.
Type 'string' is not assignable to type 'number | "toString" | "charAt" | "charCodeAt" | "concat" | "indexOf" | "lastIndexOf" | "localeCompare" | "match" | "replace" | "search" | "slice" | "split" | "substring" | "toLowerCase" | "toLocaleLowerCase" | "toUpperCase" | "toLocaleUpperCase" | "trim" | "length" | "substr" | "valueOf"'.
Type 'keyof B' is not assignable to type '"valueOf"'.
Type 'string | number | symbol' is not assignable to type '"valueOf"'.
Type 'string' is not assignable to type '"valueOf"'.
Type 'string' is not assignable to type 'number | "toString" | "charAt" | "charCodeAt" | "concat" | "indexOf" | "lastIndexOf" | "localeCompare" | "match" | "replace" | "search" | "slice" | "split" | "substring" | "toLowerCase" | "toLocaleLowerCase" | "toUpperCase" | "toLocaleUpperCase" | "trim" | "length" | "substr" | "valueOf" | keyof A'.
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@weswigham weswigham May 13, 2019 •
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did keyof A expand into... itself? o.O

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In the first keyof A, A is a substitution type. It then gets expanded into keyof (A & string) which becomes the union that ends in keyof A where A is the actual type variable. Not ideal, but neither was the prior error message.

Type 'keyof B' is not assignable to type 'number | "toString" | "charAt" | "charCodeAt" | "concat" | "indexOf" | "lastIndexOf" | "localeCompare" | "match" | "replace" | "search" | "slice" | "split" | "substring" | "toLowerCase" | "toLocaleLowerCase" | "toUpperCase" | "toLocaleUpperCase" | "trim" | "length" | "substr" | "valueOf" | keyof A'.
Type 'string | number | symbol' is not assignable to type 'number | "toString" | "charAt" | "charCodeAt" | "concat" | "indexOf" | "lastIndexOf" | "localeCompare" | "match" | "replace" | "search" | "slice" | "split" | "substring" | "toLowerCase" | "toLocaleLowerCase" | "toUpperCase" | "toLocaleUpperCase" | "trim" | "length" | "substr" | "valueOf" | keyof A'.
Type 'string' is not assignable to type 'number | "toString" | "charAt" | "charCodeAt" | "concat" | "indexOf" | "lastIndexOf" | "localeCompare" | "match" | "replace" | "search" | "slice" | "split" | "substring" | "toLowerCase" | "toLocaleLowerCase" | "toUpperCase" | "toLocaleUpperCase" | "trim" | "length" | "substr" | "valueOf" | keyof A'.
Type 'keyof B' is not assignable to type 'keyof A'.
Type 'string | number | symbol' is not assignable to type 'keyof A'.
Type 'string' is not assignable to type 'keyof A'.
tests/cases/conformance/types/conditional/conditionalTypes2.ts(25,5): error TS2322: Type 'Invariant<A>' is not assignable to type 'Invariant<B>'.
Types of property 'foo' are incompatible.
Type 'A extends string ? keyof A : A' is not assignable to type 'B extends string ? keyof B : B'.
Expand Down Expand Up @@ -73,13 +73,13 @@ tests/cases/conformance/types/conditional/conditionalTypes2.ts(75,12): error TS2
!!! error TS2322: Type 'keyof B' is not assignable to type 'keyof A'.
!!! error TS2322: Type 'string | number | symbol' is not assignable to type 'keyof A'.
!!! error TS2322: Type 'string' is not assignable to type 'keyof A'.
!!! error TS2322: Type 'string' is not assignable to type 'number | "toString" | "charAt" | "charCodeAt" | "concat" | "indexOf" | "lastIndexOf" | "localeCompare" | "match" | "replace" | "search" | "slice" | "split" | "substring" | "toLowerCase" | "toLocaleLowerCase" | "toUpperCase" | "toLocaleUpperCase" | "trim" | "length" | "substr" | "valueOf"'.
!!! error TS2322: Type 'keyof B' is not assignable to type 'number | "toString" | "charAt" | "charCodeAt" | "concat" | "indexOf" | "lastIndexOf" | "localeCompare" | "match" | "replace" | "search" | "slice" | "split" | "substring" | "toLowerCase" | "toLocaleLowerCase" | "toUpperCase" | "toLocaleUpperCase" | "trim" | "length" | "substr" | "valueOf"'.
!!! error TS2322: Type 'string | number | symbol' is not assignable to type 'number | "toString" | "charAt" | "charCodeAt" | "concat" | "indexOf" | "lastIndexOf" | "localeCompare" | "match" | "replace" | "search" | "slice" | "split" | "substring" | "toLowerCase" | "toLocaleLowerCase" | "toUpperCase" | "toLocaleUpperCase" | "trim" | "length" | "substr" | "valueOf"'.
!!! error TS2322: Type 'string' is not assignable to type 'number | "toString" | "charAt" | "charCodeAt" | "concat" | "indexOf" | "lastIndexOf" | "localeCompare" | "match" | "replace" | "search" | "slice" | "split" | "substring" | "toLowerCase" | "toLocaleLowerCase" | "toUpperCase" | "toLocaleUpperCase" | "trim" | "length" | "substr" | "valueOf"'.
!!! error TS2322: Type 'keyof B' is not assignable to type '"valueOf"'.
!!! error TS2322: Type 'string | number | symbol' is not assignable to type '"valueOf"'.
!!! error TS2322: Type 'string' is not assignable to type '"valueOf"'.
!!! error TS2322: Type 'string' is not assignable to type 'number | "toString" | "charAt" | "charCodeAt" | "concat" | "indexOf" | "lastIndexOf" | "localeCompare" | "match" | "replace" | "search" | "slice" | "split" | "substring" | "toLowerCase" | "toLocaleLowerCase" | "toUpperCase" | "toLocaleUpperCase" | "trim" | "length" | "substr" | "valueOf" | keyof A'.
!!! error TS2322: Type 'keyof B' is not assignable to type 'number | "toString" | "charAt" | "charCodeAt" | "concat" | "indexOf" | "lastIndexOf" | "localeCompare" | "match" | "replace" | "search" | "slice" | "split" | "substring" | "toLowerCase" | "toLocaleLowerCase" | "toUpperCase" | "toLocaleUpperCase" | "trim" | "length" | "substr" | "valueOf" | keyof A'.
!!! error TS2322: Type 'string | number | symbol' is not assignable to type 'number | "toString" | "charAt" | "charCodeAt" | "concat" | "indexOf" | "lastIndexOf" | "localeCompare" | "match" | "replace" | "search" | "slice" | "split" | "substring" | "toLowerCase" | "toLocaleLowerCase" | "toUpperCase" | "toLocaleUpperCase" | "trim" | "length" | "substr" | "valueOf" | keyof A'.
!!! error TS2322: Type 'string' is not assignable to type 'number | "toString" | "charAt" | "charCodeAt" | "concat" | "indexOf" | "lastIndexOf" | "localeCompare" | "match" | "replace" | "search" | "slice" | "split" | "substring" | "toLowerCase" | "toLocaleLowerCase" | "toUpperCase" | "toLocaleUpperCase" | "trim" | "length" | "substr" | "valueOf" | keyof A'.
!!! error TS2322: Type 'keyof B' is not assignable to type 'keyof A'.
!!! error TS2322: Type 'string | number | symbol' is not assignable to type 'keyof A'.
!!! error TS2322: Type 'string' is not assignable to type 'keyof A'.
b = a; // Error
~
!!! error TS2322: Type 'Invariant<A>' is not assignable to type 'Invariant<B>'.
Expand Down
96 changes: 48 additions & 48 deletions tests/baselines/reference/conditionalTypesSimplifyWhenTrivial.types
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@@ -1,49 +1,49 @@
=== tests/cases/compiler/conditionalTypesSimplifyWhenTrivial.ts ===
const fn1 = <Params>(
>fn1 : <Params>(params: Pick<Params, keyof Params>) => Params
><Params>( params: Pick<Params, Exclude<keyof Params, never>>,): Params => params : <Params>(params: Pick<Params, keyof Params>) => Params
>fn1 : <Params>(params: Pick<Params, Exclude<keyof Params, never>>) => Params
><Params>( params: Pick<Params, Exclude<keyof Params, never>>,): Params => params : <Params>(params: Pick<Params, Exclude<keyof Params, never>>) => Params

params: Pick<Params, Exclude<keyof Params, never>>,
>params : Pick<Params, keyof Params>
>params : Pick<Params, Exclude<keyof Params, never>>

): Params => params;
>params : Pick<Params, keyof Params>
>params : Pick<Params, Exclude<keyof Params, never>>

function fn2<T>(x: Exclude<T, never>) {
>fn2 : <T>(x: T) => void
>x : T
>fn2 : <T>(x: Exclude<T, never>) => void
>x : Exclude<T, never>

var y: T = x;
>y : T
>x : T
>x : Exclude<T, never>

x = y;
>x = y : T
>x : T
>x : Exclude<T, never>
>y : T
}

const fn3 = <Params>(
>fn3 : <Params>(params: Pick<Params, keyof Params>) => Params
><Params>( params: Pick<Params, Extract<keyof Params, keyof Params>>,): Params => params : <Params>(params: Pick<Params, keyof Params>) => Params
>fn3 : <Params>(params: Pick<Params, Extract<keyof Params, keyof Params>>) => Params
><Params>( params: Pick<Params, Extract<keyof Params, keyof Params>>,): Params => params : <Params>(params: Pick<Params, Extract<keyof Params, keyof Params>>) => Params

params: Pick<Params, Extract<keyof Params, keyof Params>>,
>params : Pick<Params, keyof Params>
>params : Pick<Params, Extract<keyof Params, keyof Params>>

): Params => params;
>params : Pick<Params, keyof Params>
>params : Pick<Params, Extract<keyof Params, keyof Params>>

function fn4<T>(x: Extract<T, T>) {
>fn4 : <T>(x: T) => void
>x : T
>fn4 : <T>(x: Extract<T, T>) => void
>x : Extract<T, T>

var y: T = x;
>y : T
>x : T
>x : Extract<T, T>

x = y;
>x = y : T
>x : T
>x : Extract<T, T>
>y : T
}

Expand All @@ -57,101 +57,101 @@ type ExcludeWithDefault<T, U, D = never> = T extends U ? D : T;
>ExcludeWithDefault : ExcludeWithDefault<T, U, D>

const fn5 = <Params>(
>fn5 : <Params>(params: Pick<Params, keyof Params>) => Params
><Params>( params: Pick<Params, ExcludeWithDefault<keyof Params, never>>,): Params => params : <Params>(params: Pick<Params, keyof Params>) => Params
>fn5 : <Params>(params: Pick<Params, ExcludeWithDefault<keyof Params, never, never>>) => Params
><Params>( params: Pick<Params, ExcludeWithDefault<keyof Params, never>>,): Params => params : <Params>(params: Pick<Params, ExcludeWithDefault<keyof Params, never, never>>) => Params

params: Pick<Params, ExcludeWithDefault<keyof Params, never>>,
>params : Pick<Params, keyof Params>
>params : Pick<Params, ExcludeWithDefault<keyof Params, never, never>>

): Params => params;
>params : Pick<Params, keyof Params>
>params : Pick<Params, ExcludeWithDefault<keyof Params, never, never>>

function fn6<T>(x: ExcludeWithDefault<T, never>) {
>fn6 : <T>(x: T) => void
>x : T
>fn6 : <T>(x: ExcludeWithDefault<T, never, never>) => void
>x : ExcludeWithDefault<T, never, never>

var y: T = x;
>y : T
>x : T
>x : ExcludeWithDefault<T, never, never>

x = y;
>x = y : T
>x : T
>x : ExcludeWithDefault<T, never, never>
>y : T
}

const fn7 = <Params>(
>fn7 : <Params>(params: Pick<Params, keyof Params>) => Params
><Params>( params: Pick<Params, ExtractWithDefault<keyof Params, keyof Params>>,): Params => params : <Params>(params: Pick<Params, keyof Params>) => Params
>fn7 : <Params>(params: Pick<Params, ExtractWithDefault<keyof Params, keyof Params, never>>) => Params
><Params>( params: Pick<Params, ExtractWithDefault<keyof Params, keyof Params>>,): Params => params : <Params>(params: Pick<Params, ExtractWithDefault<keyof Params, keyof Params, never>>) => Params

params: Pick<Params, ExtractWithDefault<keyof Params, keyof Params>>,
>params : Pick<Params, keyof Params>
>params : Pick<Params, ExtractWithDefault<keyof Params, keyof Params, never>>

): Params => params;
>params : Pick<Params, keyof Params>
>params : Pick<Params, ExtractWithDefault<keyof Params, keyof Params, never>>

function fn8<T>(x: ExtractWithDefault<T, T>) {
>fn8 : <T>(x: T) => void
>x : T
>fn8 : <T>(x: ExtractWithDefault<T, T, never>) => void
>x : ExtractWithDefault<T, T, never>

var y: T = x;
>y : T
>x : T
>x : ExtractWithDefault<T, T, never>

x = y;
>x = y : T
>x : T
>x : ExtractWithDefault<T, T, never>
>y : T
}

type TemplatedConditional<TCheck, TExtends, TTrue, TFalse> = TCheck extends TExtends ? TTrue : TFalse;
>TemplatedConditional : TemplatedConditional<TCheck, TExtends, TTrue, TFalse>

const fn9 = <Params>(
>fn9 : <Params>(params: Pick<Params, keyof Params>) => Params
><Params>( params: Pick<Params, TemplatedConditional<keyof Params, never, never, keyof Params>>,): Params => params : <Params>(params: Pick<Params, keyof Params>) => Params
>fn9 : <Params>(params: Pick<Params, TemplatedConditional<keyof Params, never, never, keyof Params>>) => Params
><Params>( params: Pick<Params, TemplatedConditional<keyof Params, never, never, keyof Params>>,): Params => params : <Params>(params: Pick<Params, TemplatedConditional<keyof Params, never, never, keyof Params>>) => Params

params: Pick<Params, TemplatedConditional<keyof Params, never, never, keyof Params>>,
>params : Pick<Params, keyof Params>
>params : Pick<Params, TemplatedConditional<keyof Params, never, never, keyof Params>>

): Params => params;
>params : Pick<Params, keyof Params>
>params : Pick<Params, TemplatedConditional<keyof Params, never, never, keyof Params>>

function fn10<T>(x: TemplatedConditional<T, never, never, T>) {
>fn10 : <T>(x: T) => void
>x : T
>fn10 : <T>(x: TemplatedConditional<T, never, never, T>) => void
>x : TemplatedConditional<T, never, never, T>

var y: T = x;
>y : T
>x : T
>x : TemplatedConditional<T, never, never, T>

x = y;
>x = y : T
>x : T
>x : TemplatedConditional<T, never, never, T>
>y : T
}

const fn11 = <Params>(
>fn11 : <Params>(params: Pick<Params, keyof Params>) => Params
><Params>( params: Pick<Params, TemplatedConditional<keyof Params, keyof Params, keyof Params, never>>,): Params => params : <Params>(params: Pick<Params, keyof Params>) => Params
>fn11 : <Params>(params: Pick<Params, TemplatedConditional<keyof Params, keyof Params, keyof Params, never>>) => Params
><Params>( params: Pick<Params, TemplatedConditional<keyof Params, keyof Params, keyof Params, never>>,): Params => params : <Params>(params: Pick<Params, TemplatedConditional<keyof Params, keyof Params, keyof Params, never>>) => Params

params: Pick<Params, TemplatedConditional<keyof Params, keyof Params, keyof Params, never>>,
>params : Pick<Params, keyof Params>
>params : Pick<Params, TemplatedConditional<keyof Params, keyof Params, keyof Params, never>>

): Params => params;
>params : Pick<Params, keyof Params>
>params : Pick<Params, TemplatedConditional<keyof Params, keyof Params, keyof Params, never>>

function fn12<T>(x: TemplatedConditional<T, T, T, never>) {
>fn12 : <T>(x: T) => void
>x : T
>fn12 : <T>(x: TemplatedConditional<T, T, T, never>) => void
>x : TemplatedConditional<T, T, T, never>

var y: T = x;
>y : T
>x : T
>x : TemplatedConditional<T, T, T, never>

x = y;
>x = y : T
>x : T
>x : TemplatedConditional<T, T, T, never>
>y : T
}

Expand Down
2 changes: 1 addition & 1 deletion tests/baselines/reference/inlinedAliasAssignableToConstraintSameAsAlias.types
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Expand Up @@ -31,7 +31,7 @@ class A {
>z : A[]

whereRelated< // Works // Type is same as A1, but is not assignable to type A
>whereRelated : <RF extends RelationFields = RelationFields, N extends "x" | "y" | "z" = "x" | "y" | "z", A1 extends A = RF[N] extends A[] ? RF[N][0] : never, A2 extends A = RF[N] extends A[] ? RF[N][0] : never>() => number
>whereRelated : <RF extends RelationFields = RelationFields, N extends "x" | "y" | "z" = "x" | "y" | "z", A1 extends A = RF[N] extends A[] ? RF[N][0] : never, A2 extends A = ShouldA<RF, N>>() => number

RF extends RelationFields = RelationFields,
N extends Name = Name,
Expand Down
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