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More complete check in isConstTypeVariable #53341

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Apr 1, 2023
Merged

More complete check in isConstTypeVariable #53341

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30d044e
More complete check in isConstTypeVariable
ahejlsberg Mar 18, 2023
9eb3d5a
Add tests
ahejlsberg Mar 18, 2023
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19 changes: 9 additions & 10 deletions src/compiler/checker.ts
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Expand Up @@ -13545,10 +13545,14 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
return hasNonCircularBaseConstraint(typeParameter) ? getConstraintFromTypeParameter(typeParameter) : undefined;
}

function isConstTypeVariable(type: Type): boolean {
return !!(type.flags & TypeFlags.TypeParameter && some((type as TypeParameter).symbol?.declarations, d => hasSyntacticModifier(d, ModifierFlags.Const)) ||
isGenericTupleType(type) && findIndex(getTypeArguments(type), (t, i) => !!(type.target.elementFlags[i] & ElementFlags.Variadic) && isConstTypeVariable(t)) >= 0 ||
type.flags & TypeFlags.IndexedAccess && isConstTypeVariable((type as IndexedAccessType).objectType));
function isConstTypeVariable(type: Type | undefined): boolean {
return !!(type && (
type.flags & TypeFlags.TypeParameter && some((type as TypeParameter).symbol?.declarations, d => hasSyntacticModifier(d, ModifierFlags.Const)) ||
type.flags & TypeFlags.Union && some((type as UnionType).types, isConstTypeVariable) ||
type.flags & TypeFlags.IndexedAccess && isConstTypeVariable((type as IndexedAccessType).objectType) ||
type.flags & TypeFlags.Conditional && isConstTypeVariable(getConstraintOfConditionalType(type as ConditionalType)) ||
type.flags & TypeFlags.Substitution && isConstTypeVariable((type as SubstitutionType).baseType) ||
isGenericTupleType(type) && findIndex(getTypeArguments(type), (t, i) => !!(type.target.elementFlags[i] & ElementFlags.Variadic) && isConstTypeVariable(t)) >= 0));
}

function getConstraintOfIndexedAccess(type: IndexedAccessType) {
Expand Down Expand Up @@ -37258,16 +37262,11 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
const parent = node.parent;
return isAssertionExpression(parent) && isConstTypeReference(parent.type) ||
isJSDocTypeAssertion(parent) && isConstTypeReference(getJSDocTypeAssertionType(parent)) ||
isValidConstAssertionArgument(node) && isConstTypeParameterContext(node) ||
isValidConstAssertionArgument(node) && isConstTypeVariable(getContextualType(node, ContextFlags.None)) ||
(isParenthesizedExpression(parent) || isArrayLiteralExpression(parent) || isSpreadElement(parent)) && isConstContext(parent) ||
(isPropertyAssignment(parent) || isShorthandPropertyAssignment(parent) || isTemplateSpan(parent)) && isConstContext(parent.parent);
}

function isConstTypeParameterContext(node: Expression) {
const contextualType = getContextualType(node, ContextFlags.None);
return !!contextualType && someType(contextualType, isConstTypeVariable);
}

function checkExpressionForMutableLocation(node: Expression, checkMode: CheckMode | undefined, forceTuple?: boolean): Type {
const type = checkExpression(node, checkMode, forceTuple);
return isConstContext(node) || isCommonJsExportedExpression(node) ? getRegularTypeOfLiteralType(type) :
Expand Down
14 changes: 14 additions & 0 deletions tests/baselines/reference/typeParameterConstModifiers.errors.txt
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Expand Up @@ -91,4 +91,18 @@ tests/cases/conformance/types/typeParameters/typeParameterLists/typeParameterCon
declare function inners2<const T extends readonly any[]>(args: readonly [unknown, ...T, unknown]): T;

const test2 = inners2([1,2,3,4,5]);

// Repro from #53307

type NotEmpty<T extends Record<string, any>> = keyof T extends never ? never : T;

const thing = <const O extends Record<string, any>>(o: NotEmpty<O>) => o;

const t = thing({ foo: '' }); // readonly { foo: "" }

type NotEmptyMapped<T extends Record<string, any>> = keyof T extends never ? never : { [K in keyof T]: T[K] };

const thingMapped = <const O extends Record<string, any>>(o: NotEmptyMapped<O>) => o;

const tMapped = thingMapped({ foo: '' }); // { foo: "" }

18 changes: 18 additions & 0 deletions tests/baselines/reference/typeParameterConstModifiers.js
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Expand Up @@ -83,6 +83,20 @@ const test = inners(1,2,3,4,5);
declare function inners2<const T extends readonly any[]>(args: readonly [unknown, ...T, unknown]): T;

const test2 = inners2([1,2,3,4,5]);

// Repro from #53307

type NotEmpty<T extends Record<string, any>> = keyof T extends never ? never : T;

const thing = <const O extends Record<string, any>>(o: NotEmpty<O>) => o;

const t = thing({ foo: '' }); // readonly { foo: "" }

type NotEmptyMapped<T extends Record<string, any>> = keyof T extends never ? never : { [K in keyof T]: T[K] };

const thingMapped = <const O extends Record<string, any>>(o: NotEmptyMapped<O>) => o;

const tMapped = thingMapped({ foo: '' }); // { foo: "" }


//// [typeParameterConstModifiers.js]
Expand Down Expand Up @@ -130,3 +144,7 @@ function set(obj, path, value) { }
set(obj, ['a', 'b', 'c'], value);
var test = inners(1, 2, 3, 4, 5);
var test2 = inners2([1, 2, 3, 4, 5]);
var thing = function (o) { return o; };
var t = thing({ foo: '' }); // readonly { foo: "" }
var thingMapped = function (o) { return o; };
var tMapped = thingMapped({ foo: '' }); // { foo: "" }
47 changes: 47 additions & 0 deletions tests/baselines/reference/typeParameterConstModifiers.symbols
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Expand Up @@ -304,3 +304,50 @@ const test2 = inners2([1,2,3,4,5]);
>test2 : Symbol(test2, Decl(typeParameterConstModifiers.ts, 83, 5))
>inners2 : Symbol(inners2, Decl(typeParameterConstModifiers.ts, 79, 31))

// Repro from #53307

type NotEmpty<T extends Record<string, any>> = keyof T extends never ? never : T;
>NotEmpty : Symbol(NotEmpty, Decl(typeParameterConstModifiers.ts, 83, 35))
>T : Symbol(T, Decl(typeParameterConstModifiers.ts, 87, 14))
>Record : Symbol(Record, Decl(lib.es5.d.ts, --, --))
>T : Symbol(T, Decl(typeParameterConstModifiers.ts, 87, 14))
>T : Symbol(T, Decl(typeParameterConstModifiers.ts, 87, 14))

const thing = <const O extends Record<string, any>>(o: NotEmpty<O>) => o;
>thing : Symbol(thing, Decl(typeParameterConstModifiers.ts, 89, 5))
>O : Symbol(O, Decl(typeParameterConstModifiers.ts, 89, 15))
>Record : Symbol(Record, Decl(lib.es5.d.ts, --, --))
>o : Symbol(o, Decl(typeParameterConstModifiers.ts, 89, 52))
>NotEmpty : Symbol(NotEmpty, Decl(typeParameterConstModifiers.ts, 83, 35))
>O : Symbol(O, Decl(typeParameterConstModifiers.ts, 89, 15))
>o : Symbol(o, Decl(typeParameterConstModifiers.ts, 89, 52))

const t = thing({ foo: '' }); // readonly { foo: "" }
>t : Symbol(t, Decl(typeParameterConstModifiers.ts, 91, 5))
>thing : Symbol(thing, Decl(typeParameterConstModifiers.ts, 89, 5))
>foo : Symbol(foo, Decl(typeParameterConstModifiers.ts, 91, 17))

type NotEmptyMapped<T extends Record<string, any>> = keyof T extends never ? never : { [K in keyof T]: T[K] };
>NotEmptyMapped : Symbol(NotEmptyMapped, Decl(typeParameterConstModifiers.ts, 91, 29))
>T : Symbol(T, Decl(typeParameterConstModifiers.ts, 93, 20))
>Record : Symbol(Record, Decl(lib.es5.d.ts, --, --))
>T : Symbol(T, Decl(typeParameterConstModifiers.ts, 93, 20))
>K : Symbol(K, Decl(typeParameterConstModifiers.ts, 93, 88))
>T : Symbol(T, Decl(typeParameterConstModifiers.ts, 93, 20))
>T : Symbol(T, Decl(typeParameterConstModifiers.ts, 93, 20))
>K : Symbol(K, Decl(typeParameterConstModifiers.ts, 93, 88))

const thingMapped = <const O extends Record<string, any>>(o: NotEmptyMapped<O>) => o;
>thingMapped : Symbol(thingMapped, Decl(typeParameterConstModifiers.ts, 95, 5))
>O : Symbol(O, Decl(typeParameterConstModifiers.ts, 95, 21))
>Record : Symbol(Record, Decl(lib.es5.d.ts, --, --))
>o : Symbol(o, Decl(typeParameterConstModifiers.ts, 95, 58))
>NotEmptyMapped : Symbol(NotEmptyMapped, Decl(typeParameterConstModifiers.ts, 91, 29))
>O : Symbol(O, Decl(typeParameterConstModifiers.ts, 95, 21))
>o : Symbol(o, Decl(typeParameterConstModifiers.ts, 95, 58))

const tMapped = thingMapped({ foo: '' }); // { foo: "" }
>tMapped : Symbol(tMapped, Decl(typeParameterConstModifiers.ts, 97, 5))
>thingMapped : Symbol(thingMapped, Decl(typeParameterConstModifiers.ts, 95, 5))
>foo : Symbol(foo, Decl(typeParameterConstModifiers.ts, 97, 29))

36 changes: 36 additions & 0 deletions tests/baselines/reference/typeParameterConstModifiers.types
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Expand Up @@ -350,3 +350,39 @@ const test2 = inners2([1,2,3,4,5]);
>4 : 4
>5 : 5

// Repro from #53307

type NotEmpty<T extends Record<string, any>> = keyof T extends never ? never : T;
>NotEmpty : NotEmpty<T>

const thing = <const O extends Record<string, any>>(o: NotEmpty<O>) => o;
>thing : <const O extends Record<string, any>>(o: NotEmpty<O>) => NotEmpty<O>
><const O extends Record<string, any>>(o: NotEmpty<O>) => o : <const O extends Record<string, any>>(o: NotEmpty<O>) => NotEmpty<O>
>o : NotEmpty<O>
>o : NotEmpty<O>

const t = thing({ foo: '' }); // readonly { foo: "" }
>t : { readonly foo: ""; }
>thing({ foo: '' }) : { readonly foo: ""; }
>thing : <const O extends Record<string, any>>(o: NotEmpty<O>) => NotEmpty<O>
>{ foo: '' } : { foo: ""; }
>foo : ""
>'' : ""

type NotEmptyMapped<T extends Record<string, any>> = keyof T extends never ? never : { [K in keyof T]: T[K] };
>NotEmptyMapped : NotEmptyMapped<T>

const thingMapped = <const O extends Record<string, any>>(o: NotEmptyMapped<O>) => o;
>thingMapped : <const O extends Record<string, any>>(o: NotEmptyMapped<O>) => NotEmptyMapped<O>
><const O extends Record<string, any>>(o: NotEmptyMapped<O>) => o : <const O extends Record<string, any>>(o: NotEmptyMapped<O>) => NotEmptyMapped<O>
>o : NotEmptyMapped<O>
>o : NotEmptyMapped<O>

const tMapped = thingMapped({ foo: '' }); // { foo: "" }
>tMapped : { foo: ""; }
>thingMapped({ foo: '' }) : { foo: ""; }
>thingMapped : <const O extends Record<string, any>>(o: NotEmptyMapped<O>) => NotEmptyMapped<O>
>{ foo: '' } : { foo: ""; }
>foo : ""
>'' : ""

14 changes: 14 additions & 0 deletions .../cases/conformance/types/typeParameters/typeParameterLists/typeParameterConstModifiers.ts
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Expand Up @@ -84,3 +84,17 @@ const test = inners(1,2,3,4,5);
declare function inners2<const T extends readonly any[]>(args: readonly [unknown, ...T, unknown]): T;

const test2 = inners2([1,2,3,4,5]);

// Repro from #53307

type NotEmpty<T extends Record<string, any>> = keyof T extends never ? never : T;

const thing = <const O extends Record<string, any>>(o: NotEmpty<O>) => o;

const t = thing({ foo: '' }); // readonly { foo: "" }

type NotEmptyMapped<T extends Record<string, any>> = keyof T extends never ? never : { [K in keyof T]: T[K] };

const thingMapped = <const O extends Record<string, any>>(o: NotEmptyMapped<O>) => o;

const tMapped = thingMapped({ foo: '' }); // { foo: "" }