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Strip literal freshness when contextually typed by instantiable type that has return mapper constraint inferences
1 parent e37ea53 commit 410d2f7

5 files changed

+201
-1
lines changed

‎src/compiler/checker.ts

Lines changed: 3 additions & 1 deletion
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@@ -34796,7 +34796,9 @@ namespace ts {
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// We strip literal freshness when an appropriate contextual type is present such that contextually typed
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// literals always preserve their literal types (otherwise they might widen during type inference). An alternative
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// here would be to not mark contextually typed literals as fresh in the first place.
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const result = maybeTypeOfKind(type, TypeFlags.Literal) && isLiteralOfContextualType(type, instantiateContextualType(contextualType, node, /*contextFlags*/ undefined)) ?
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const result = maybeTypeOfKind(type, TypeFlags.Literal) && (
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isLiteralOfContextualType(type, instantiateContextualType(contextualType, node, /*contextFlags*/ undefined)) ||
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isLiteralOfContextualType(type, contextualType)) ?
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getRegularTypeOfLiteralType(type) : type;
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return result;
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}

‎tests/baselines/reference/stringLiteralFreshnessInGenericTypeGuard.js

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//// [stringLiteralFreshnessInGenericTypeGuard.ts]
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interface Guard<T> {
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(val: unknown): val is T;
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}
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type ObjectGuard<T> = {
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[key in keyof T]: Guard<T[key]>;
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};
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function isObject(val: unknown): val is Record<string, unknown> {
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return val !== undefined && val !== null && typeof val === 'object' && !Array.isArray(val);
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}
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declare function createObjectGuard<T>(guard: ObjectGuard<T>): (val: unknown) => val is T;
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declare function asLiteral<T extends (string | boolean | number)[]>(...literals: T): (val: unknown) => val is T[number]
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// See type of `isWorking` - should include the type key as a union of strings
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const isWorking = createObjectGuard({
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// ^?
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type: asLiteral('these', 'should', 'be', 'a', 'union'),
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});
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//// [stringLiteralFreshnessInGenericTypeGuard.js]
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function isObject(val) {
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return val !== undefined && val !== null && typeof val === 'object' && !Array.isArray(val);
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}
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// See type of `isWorking` - should include the type key as a union of strings
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var isWorking = createObjectGuard({
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// ^?
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type: asLiteral('these', 'should', 'be', 'a', 'union')
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});

‎tests/baselines/reference/stringLiteralFreshnessInGenericTypeGuard.symbols

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=== tests/cases/compiler/stringLiteralFreshnessInGenericTypeGuard.ts ===
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interface Guard<T> {
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>Guard : Symbol(Guard, Decl(stringLiteralFreshnessInGenericTypeGuard.ts, 0, 0))
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>T : Symbol(T, Decl(stringLiteralFreshnessInGenericTypeGuard.ts, 0, 16))
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(val: unknown): val is T;
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>val : Symbol(val, Decl(stringLiteralFreshnessInGenericTypeGuard.ts, 1, 3))
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>val : Symbol(val, Decl(stringLiteralFreshnessInGenericTypeGuard.ts, 1, 3))
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>T : Symbol(T, Decl(stringLiteralFreshnessInGenericTypeGuard.ts, 0, 16))
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}
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type ObjectGuard<T> = {
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>ObjectGuard : Symbol(ObjectGuard, Decl(stringLiteralFreshnessInGenericTypeGuard.ts, 2, 1))
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>T : Symbol(T, Decl(stringLiteralFreshnessInGenericTypeGuard.ts, 4, 17))
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[key in keyof T]: Guard<T[key]>;
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>key : Symbol(key, Decl(stringLiteralFreshnessInGenericTypeGuard.ts, 5, 3))
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>T : Symbol(T, Decl(stringLiteralFreshnessInGenericTypeGuard.ts, 4, 17))
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>Guard : Symbol(Guard, Decl(stringLiteralFreshnessInGenericTypeGuard.ts, 0, 0))
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>T : Symbol(T, Decl(stringLiteralFreshnessInGenericTypeGuard.ts, 4, 17))
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>key : Symbol(key, Decl(stringLiteralFreshnessInGenericTypeGuard.ts, 5, 3))
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};
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function isObject(val: unknown): val is Record<string, unknown> {
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>isObject : Symbol(isObject, Decl(stringLiteralFreshnessInGenericTypeGuard.ts, 6, 2))
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>val : Symbol(val, Decl(stringLiteralFreshnessInGenericTypeGuard.ts, 8, 18))
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>val : Symbol(val, Decl(stringLiteralFreshnessInGenericTypeGuard.ts, 8, 18))
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>Record : Symbol(Record, Decl(lib.es5.d.ts, --, --))
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return val !== undefined && val !== null && typeof val === 'object' && !Array.isArray(val);
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>val : Symbol(val, Decl(stringLiteralFreshnessInGenericTypeGuard.ts, 8, 18))
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>undefined : Symbol(undefined)
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>val : Symbol(val, Decl(stringLiteralFreshnessInGenericTypeGuard.ts, 8, 18))
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>val : Symbol(val, Decl(stringLiteralFreshnessInGenericTypeGuard.ts, 8, 18))
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>Array.isArray : Symbol(ArrayConstructor.isArray, Decl(lib.es5.d.ts, --, --))
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>Array : Symbol(Array, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
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>isArray : Symbol(ArrayConstructor.isArray, Decl(lib.es5.d.ts, --, --))
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>val : Symbol(val, Decl(stringLiteralFreshnessInGenericTypeGuard.ts, 8, 18))
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}
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declare function createObjectGuard<T>(guard: ObjectGuard<T>): (val: unknown) => val is T;
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>createObjectGuard : Symbol(createObjectGuard, Decl(stringLiteralFreshnessInGenericTypeGuard.ts, 10, 1))
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>T : Symbol(T, Decl(stringLiteralFreshnessInGenericTypeGuard.ts, 12, 35))
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>guard : Symbol(guard, Decl(stringLiteralFreshnessInGenericTypeGuard.ts, 12, 38))
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>ObjectGuard : Symbol(ObjectGuard, Decl(stringLiteralFreshnessInGenericTypeGuard.ts, 2, 1))
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>T : Symbol(T, Decl(stringLiteralFreshnessInGenericTypeGuard.ts, 12, 35))
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>val : Symbol(val, Decl(stringLiteralFreshnessInGenericTypeGuard.ts, 12, 63))
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>val : Symbol(val, Decl(stringLiteralFreshnessInGenericTypeGuard.ts, 12, 63))
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>T : Symbol(T, Decl(stringLiteralFreshnessInGenericTypeGuard.ts, 12, 35))
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declare function asLiteral<T extends (string | boolean | number)[]>(...literals: T): (val: unknown) => val is T[number]
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>asLiteral : Symbol(asLiteral, Decl(stringLiteralFreshnessInGenericTypeGuard.ts, 12, 89))
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>T : Symbol(T, Decl(stringLiteralFreshnessInGenericTypeGuard.ts, 14, 27))
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>literals : Symbol(literals, Decl(stringLiteralFreshnessInGenericTypeGuard.ts, 14, 68))
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>T : Symbol(T, Decl(stringLiteralFreshnessInGenericTypeGuard.ts, 14, 27))
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>val : Symbol(val, Decl(stringLiteralFreshnessInGenericTypeGuard.ts, 14, 86))
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>val : Symbol(val, Decl(stringLiteralFreshnessInGenericTypeGuard.ts, 14, 86))
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>T : Symbol(T, Decl(stringLiteralFreshnessInGenericTypeGuard.ts, 14, 27))
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// See type of `isWorking` - should include the type key as a union of strings
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const isWorking = createObjectGuard({
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>isWorking : Symbol(isWorking, Decl(stringLiteralFreshnessInGenericTypeGuard.ts, 17, 5))
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>createObjectGuard : Symbol(createObjectGuard, Decl(stringLiteralFreshnessInGenericTypeGuard.ts, 10, 1))
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// ^?
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type: asLiteral('these', 'should', 'be', 'a', 'union'),
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>type : Symbol(type, Decl(stringLiteralFreshnessInGenericTypeGuard.ts, 17, 37))
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>asLiteral : Symbol(asLiteral, Decl(stringLiteralFreshnessInGenericTypeGuard.ts, 12, 89))
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});
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‎tests/baselines/reference/stringLiteralFreshnessInGenericTypeGuard.types

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=== tests/cases/compiler/stringLiteralFreshnessInGenericTypeGuard.ts ===
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interface Guard<T> {
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(val: unknown): val is T;
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>val : unknown
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}
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type ObjectGuard<T> = {
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>ObjectGuard : ObjectGuard<T>
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[key in keyof T]: Guard<T[key]>;
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};
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function isObject(val: unknown): val is Record<string, unknown> {
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>isObject : (val: unknown) => val is Record<string, unknown>
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>val : unknown
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return val !== undefined && val !== null && typeof val === 'object' && !Array.isArray(val);
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>val !== undefined && val !== null && typeof val === 'object' && !Array.isArray(val) : boolean
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>val !== undefined && val !== null && typeof val === 'object' : boolean
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>val !== undefined && val !== null : boolean
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>val !== undefined : boolean
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>val : unknown
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>undefined : undefined
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>val !== null : boolean
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>val : unknown
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>null : null
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>typeof val === 'object' : boolean
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>typeof val : "string" | "number" | "bigint" | "boolean" | "symbol" | "undefined" | "object" | "function"
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>val : unknown
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>'object' : "object"
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>!Array.isArray(val) : boolean
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>Array.isArray(val) : boolean
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>Array.isArray : (arg: any) => arg is any[]
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>Array : ArrayConstructor
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>isArray : (arg: any) => arg is any[]
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>val : object
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}
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declare function createObjectGuard<T>(guard: ObjectGuard<T>): (val: unknown) => val is T;
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>createObjectGuard : <T>(guard: ObjectGuard<T>) => (val: unknown) => val is T
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>guard : ObjectGuard<T>
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>val : unknown
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declare function asLiteral<T extends (string | boolean | number)[]>(...literals: T): (val: unknown) => val is T[number]
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>asLiteral : <T extends (string | number | boolean)[]>(...literals: T) => (val: unknown) => val is T[number]
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>literals : T
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>val : unknown
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// See type of `isWorking` - should include the type key as a union of strings
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const isWorking = createObjectGuard({
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>isWorking : (val: unknown) => val is { type: "these" | "should" | "be" | "a" | "union"; }
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>createObjectGuard({// ^? type: asLiteral('these', 'should', 'be', 'a', 'union'),}) : (val: unknown) => val is { type: "these" | "should" | "be" | "a" | "union"; }
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>createObjectGuard : <T>(guard: ObjectGuard<T>) => (val: unknown) => val is T
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>{// ^? type: asLiteral('these', 'should', 'be', 'a', 'union'),} : { type: (val: unknown) => val is "these" | "should" | "be" | "a" | "union"; }
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// ^?
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type: asLiteral('these', 'should', 'be', 'a', 'union'),
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>type : (val: unknown) => val is "these" | "should" | "be" | "a" | "union"
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>asLiteral('these', 'should', 'be', 'a', 'union') : (val: unknown) => val is "these" | "should" | "be" | "a" | "union"
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>asLiteral : <T extends (string | number | boolean)[]>(...literals: T) => (val: unknown) => val is T[number]
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>'these' : "these"
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>'should' : "should"
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>'be' : "be"
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>'a' : "a"
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>'union' : "union"
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});
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‎tests/cases/compiler/stringLiteralFreshnessInGenericTypeGuard.ts

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interface Guard<T> {
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(val: unknown): val is T;
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}
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type ObjectGuard<T> = {
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[key in keyof T]: Guard<T[key]>;
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};
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function isObject(val: unknown): val is Record<string, unknown> {
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return val !== undefined && val !== null && typeof val === 'object' && !Array.isArray(val);
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}
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declare function createObjectGuard<T>(guard: ObjectGuard<T>): (val: unknown) => val is T;
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declare function asLiteral<T extends (string | boolean | number)[]>(...literals: T): (val: unknown) => val is T[number]
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// See type of `isWorking` - should include the type key as a union of strings
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const isWorking = createObjectGuard({
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// ^?
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type: asLiteral('these', 'should', 'be', 'a', 'union'),
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});
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