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Description
π Search Terms
indexed access substitution type array constraint
π Version & Regression Information
- This is the behavior in every version I tried
β― Playground Link
π» Code
type LiteralType = string | number | boolean;
type ValueGetter<ValueType extends LiteralType = LiteralType> = () => ValueType;
type Schema = SchemaArray | SchemaObject | LiteralType;
type SchemaArray = Array<SchemaObject | SchemaArray | LiteralType>;
type SchemaObject = {
[key: string]: SchemaObject | SchemaArray | LiteralType;
};
type InferValuesFromSchema<S extends Schema> = S extends LiteralType
? ValueGetter<S>
: S extends SchemaArray
? {
[K in keyof S]: InferValuesFromSchema<S[K]>;
}
: S extends SchemaObject
? {
[K in keyof S]: InferValuesFromSchema<S[K]>;
}
: never;
π Actual behavior
an error is reported:
Type 'S[K]' does not satisfy the constraint 'Schema'.
Type 'S[keyof S]' is not assignable to type 'Schema'.
Type 'S[string] | S[number] | S[symbol]' is not assignable to type 'Schema'.
Type 'S[string]' is not assignable to type 'Schema'.
Type 'S[string]' is not assignable to type 'SchemaObject'.
Type 'S[keyof S]' is not assignable to type 'SchemaObject'.
Type 'S[K]' is not assignable to type 'SchemaObject'.
Type 'S[keyof S]' is not assignable to type 'SchemaObject'.
Type 'S[string] | S[number] | S[symbol]' is not assignable to type 'SchemaObject'.
Type 'S[string]' is not assignable to type 'SchemaObject'.(2344)
π Expected behavior
There should be no error, S[K]
should satisfy Schema
constraint (at least since #48837 )
Additional information about the issue
A variant with an additional type alias for that array branch works OK: TS playground.