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Retain substitution types through instantiation if possible (#30059)
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5 files changed

+200
-1
lines changed

5 files changed

+200
-1
lines changed

‎src/compiler/checker.ts

Lines changed: 10 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -11062,7 +11062,13 @@ namespace ts {
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return getConditionalTypeInstantiation(<ConditionalType>type, combineTypeMappers((<ConditionalType>type).mapper, mapper));
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}
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if (flags & TypeFlags.Substitution) {
11065-
return instantiateType((<SubstitutionType>type).typeVariable, mapper);
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const maybeVariable = instantiateType((<SubstitutionType>type).typeVariable, mapper);
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if (maybeVariable.flags & TypeFlags.TypeVariable) {
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return getSubstitutionType(maybeVariable as TypeVariable, instantiateType((<SubstitutionType>type).substitute, mapper));
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}
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else {
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return maybeVariable;
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}
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}
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return type;
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}
@@ -14465,6 +14471,9 @@ namespace ts {
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}
1446614472
}
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}
14474+
else if (target.flags & TypeFlags.Substitution) {
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inferFromTypes(source, (target as SubstitutionType).typeVariable);
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}
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if (getObjectFlags(source) & ObjectFlags.Reference && getObjectFlags(target) & ObjectFlags.Reference && (<TypeReference>source).target === (<TypeReference>target).target) {
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// If source and target are references to the same generic type, infer from type arguments
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const sourceTypes = (<TypeReference>source).typeArguments || emptyArray;

‎tests/baselines/reference/inlinedAliasAssignableToConstraintSameAsAlias.js

Lines changed: 36 additions & 0 deletions
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@@ -0,0 +1,36 @@
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//// [inlinedAliasAssignableToConstraintSameAsAlias.ts]
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interface RelationFields {
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x: A;
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y: A[];
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z: A[];
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}
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type Name = keyof RelationFields;
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type ShouldA<RF extends RelationFields, N extends Name> = RF[N] extends A[]
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? RF[N][0]
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: never;
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class A {
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x: A;
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y: A[];
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z: A[];
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whereRelated< // Works // Type is same as A1, but is not assignable to type A
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RF extends RelationFields = RelationFields,
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N extends Name = Name,
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A1 extends A = RF[N] extends A[] ? RF[N][0] : never,
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A2 extends A = ShouldA<RF, N>
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>(): number {
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return 1;
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}
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}
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//// [inlinedAliasAssignableToConstraintSameAsAlias.js]
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var A = /** @class */ (function () {
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function A() {
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}
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A.prototype.whereRelated = function () {
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return 1;
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};
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return A;
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}());

‎tests/baselines/reference/inlinedAliasAssignableToConstraintSameAsAlias.symbols

Lines changed: 85 additions & 0 deletions
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@@ -0,0 +1,85 @@
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=== tests/cases/compiler/inlinedAliasAssignableToConstraintSameAsAlias.ts ===
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interface RelationFields {
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>RelationFields : Symbol(RelationFields, Decl(inlinedAliasAssignableToConstraintSameAsAlias.ts, 0, 0))
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x: A;
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>x : Symbol(RelationFields.x, Decl(inlinedAliasAssignableToConstraintSameAsAlias.ts, 0, 26))
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>A : Symbol(A, Decl(inlinedAliasAssignableToConstraintSameAsAlias.ts, 8, 10))
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y: A[];
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>y : Symbol(RelationFields.y, Decl(inlinedAliasAssignableToConstraintSameAsAlias.ts, 1, 7))
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>A : Symbol(A, Decl(inlinedAliasAssignableToConstraintSameAsAlias.ts, 8, 10))
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z: A[];
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>z : Symbol(RelationFields.z, Decl(inlinedAliasAssignableToConstraintSameAsAlias.ts, 2, 9))
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>A : Symbol(A, Decl(inlinedAliasAssignableToConstraintSameAsAlias.ts, 8, 10))
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}
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type Name = keyof RelationFields;
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>Name : Symbol(Name, Decl(inlinedAliasAssignableToConstraintSameAsAlias.ts, 4, 1))
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>RelationFields : Symbol(RelationFields, Decl(inlinedAliasAssignableToConstraintSameAsAlias.ts, 0, 0))
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type ShouldA<RF extends RelationFields, N extends Name> = RF[N] extends A[]
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>ShouldA : Symbol(ShouldA, Decl(inlinedAliasAssignableToConstraintSameAsAlias.ts, 5, 33))
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>RF : Symbol(RF, Decl(inlinedAliasAssignableToConstraintSameAsAlias.ts, 6, 13))
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>RelationFields : Symbol(RelationFields, Decl(inlinedAliasAssignableToConstraintSameAsAlias.ts, 0, 0))
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>N : Symbol(N, Decl(inlinedAliasAssignableToConstraintSameAsAlias.ts, 6, 39))
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>Name : Symbol(Name, Decl(inlinedAliasAssignableToConstraintSameAsAlias.ts, 4, 1))
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>RF : Symbol(RF, Decl(inlinedAliasAssignableToConstraintSameAsAlias.ts, 6, 13))
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>N : Symbol(N, Decl(inlinedAliasAssignableToConstraintSameAsAlias.ts, 6, 39))
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>A : Symbol(A, Decl(inlinedAliasAssignableToConstraintSameAsAlias.ts, 8, 10))
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? RF[N][0]
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>RF : Symbol(RF, Decl(inlinedAliasAssignableToConstraintSameAsAlias.ts, 6, 13))
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>N : Symbol(N, Decl(inlinedAliasAssignableToConstraintSameAsAlias.ts, 6, 39))
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: never;
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class A {
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>A : Symbol(A, Decl(inlinedAliasAssignableToConstraintSameAsAlias.ts, 8, 10))
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x: A;
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>x : Symbol(A.x, Decl(inlinedAliasAssignableToConstraintSameAsAlias.ts, 10, 9))
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>A : Symbol(A, Decl(inlinedAliasAssignableToConstraintSameAsAlias.ts, 8, 10))
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y: A[];
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>y : Symbol(A.y, Decl(inlinedAliasAssignableToConstraintSameAsAlias.ts, 11, 7))
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>A : Symbol(A, Decl(inlinedAliasAssignableToConstraintSameAsAlias.ts, 8, 10))
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z: A[];
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>z : Symbol(A.z, Decl(inlinedAliasAssignableToConstraintSameAsAlias.ts, 12, 9))
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>A : Symbol(A, Decl(inlinedAliasAssignableToConstraintSameAsAlias.ts, 8, 10))
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whereRelated< // Works // Type is same as A1, but is not assignable to type A
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>whereRelated : Symbol(A.whereRelated, Decl(inlinedAliasAssignableToConstraintSameAsAlias.ts, 13, 9))
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RF extends RelationFields = RelationFields,
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>RF : Symbol(RF, Decl(inlinedAliasAssignableToConstraintSameAsAlias.ts, 15, 15))
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>RelationFields : Symbol(RelationFields, Decl(inlinedAliasAssignableToConstraintSameAsAlias.ts, 0, 0))
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>RelationFields : Symbol(RelationFields, Decl(inlinedAliasAssignableToConstraintSameAsAlias.ts, 0, 0))
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N extends Name = Name,
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>N : Symbol(N, Decl(inlinedAliasAssignableToConstraintSameAsAlias.ts, 16, 47))
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>Name : Symbol(Name, Decl(inlinedAliasAssignableToConstraintSameAsAlias.ts, 4, 1))
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>Name : Symbol(Name, Decl(inlinedAliasAssignableToConstraintSameAsAlias.ts, 4, 1))
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A1 extends A = RF[N] extends A[] ? RF[N][0] : never,
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>A1 : Symbol(A1, Decl(inlinedAliasAssignableToConstraintSameAsAlias.ts, 17, 26))
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>A : Symbol(A, Decl(inlinedAliasAssignableToConstraintSameAsAlias.ts, 8, 10))
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>RF : Symbol(RF, Decl(inlinedAliasAssignableToConstraintSameAsAlias.ts, 15, 15))
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>N : Symbol(N, Decl(inlinedAliasAssignableToConstraintSameAsAlias.ts, 16, 47))
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>A : Symbol(A, Decl(inlinedAliasAssignableToConstraintSameAsAlias.ts, 8, 10))
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>RF : Symbol(RF, Decl(inlinedAliasAssignableToConstraintSameAsAlias.ts, 15, 15))
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>N : Symbol(N, Decl(inlinedAliasAssignableToConstraintSameAsAlias.ts, 16, 47))
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A2 extends A = ShouldA<RF, N>
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>A2 : Symbol(A2, Decl(inlinedAliasAssignableToConstraintSameAsAlias.ts, 18, 56))
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>A : Symbol(A, Decl(inlinedAliasAssignableToConstraintSameAsAlias.ts, 8, 10))
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>ShouldA : Symbol(ShouldA, Decl(inlinedAliasAssignableToConstraintSameAsAlias.ts, 5, 33))
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>RF : Symbol(RF, Decl(inlinedAliasAssignableToConstraintSameAsAlias.ts, 15, 15))
79+
>N : Symbol(N, Decl(inlinedAliasAssignableToConstraintSameAsAlias.ts, 16, 47))
80+
81+
>(): number {
82+
return 1;
83+
}
84+
}
85+

‎tests/baselines/reference/inlinedAliasAssignableToConstraintSameAsAlias.types

Lines changed: 45 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,45 @@
1+
=== tests/cases/compiler/inlinedAliasAssignableToConstraintSameAsAlias.ts ===
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interface RelationFields {
3+
x: A;
4+
>x : A
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y: A[];
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>y : A[]
8+
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z: A[];
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>z : A[]
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}
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type Name = keyof RelationFields;
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>Name : "x" | "y" | "z"
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type ShouldA<RF extends RelationFields, N extends Name> = RF[N] extends A[]
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>ShouldA : ShouldA<RF, N>
17+
18+
? RF[N][0]
19+
: never;
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class A {
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>A : A
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x: A;
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>x : A
26+
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y: A[];
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>y : A[]
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z: A[];
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>z : A[]
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33+
whereRelated< // Works // Type is same as A1, but is not assignable to type A
34+
>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
35+
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RF extends RelationFields = RelationFields,
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N extends Name = Name,
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A1 extends A = RF[N] extends A[] ? RF[N][0] : never,
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A2 extends A = ShouldA<RF, N>
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>(): number {
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return 1;
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>1 : 1
43+
}
44+
}
45+

‎tests/cases/compiler/inlinedAliasAssignableToConstraintSameAsAlias.ts

Lines changed: 24 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,24 @@
1+
interface RelationFields {
2+
x: A;
3+
y: A[];
4+
z: A[];
5+
}
6+
type Name = keyof RelationFields;
7+
type ShouldA<RF extends RelationFields, N extends Name> = RF[N] extends A[]
8+
? RF[N][0]
9+
: never;
10+
11+
class A {
12+
x: A;
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y: A[];
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z: A[];
15+
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whereRelated< // Works // Type is same as A1, but is not assignable to type A
17+
RF extends RelationFields = RelationFields,
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N extends Name = Name,
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A1 extends A = RF[N] extends A[] ? RF[N][0] : never,
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A2 extends A = ShouldA<RF, N>
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>(): number {
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return 1;
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}
24+
}

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