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Improve constraints of nested conditional types applied to constrained type variables #59886

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Improve constraints of nested conditional types applied to constrained type variables #59886

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38 changes: 27 additions & 11 deletions src/compiler/checker.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -2335,6 +2335,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
var reverseMappedSourceStack: Type[] = [];
var reverseMappedTargetStack: Type[] = [];
var reverseExpandingFlags = ExpandingFlags.None;
var distributiveConditionalConstraintIdentityStack: object[] = [];

var diagnostics = createDiagnosticCollection();
var suggestionDiagnostics = createDiagnosticCollection();
Expand Down Expand Up @@ -14286,7 +14287,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
const checkType = (type as ConditionalType).checkType;
const constraint = getLowerBoundOfKeyType(checkType);
if (constraint !== checkType) {
return getConditionalTypeInstantiation(type as ConditionalType, prependTypeMapping((type as ConditionalType).root.checkType, constraint, (type as ConditionalType).mapper), /*forConstraint*/ false);
return getConditionalTypeInstantiation(type as ConditionalType, prependTypeMapping((type as ConditionalType).root.checkType, constraint, (type as ConditionalType).mapper));
}
}
return type;
Expand Down Expand Up @@ -14754,7 +14755,11 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
const simplified = getSimplifiedType(type.checkType, /*writing*/ false);
const constraint = simplified === type.checkType ? getConstraintOfType(simplified) : simplified;
if (constraint && constraint !== type.checkType) {
const instantiated = getConditionalTypeInstantiation(type, prependTypeMapping(type.root.checkType, constraint, type.mapper), /*forConstraint*/ true);
// push an item that can't conflict with true recursion identities
// thanks to it `.length` can be checked to determine that the compiler is within `getConstraintOfDistributiveConditionalType` call
distributiveConditionalConstraintIdentityStack.push(unknownType);
const instantiated = getConditionalTypeInstantiation(type, prependTypeMapping(type.root.checkType, constraint, type.mapper));
distributiveConditionalConstraintIdentityStack.pop();
if (!(instantiated.flags & TypeFlags.Never)) {
type.resolvedConstraintOfDistributive = instantiated;
return instantiated;
Expand Down Expand Up @@ -19252,7 +19257,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
return isGenericType(type) || checkTuples && isTupleType(type) && some(getElementTypes(type), isGenericType);
}

function getConditionalType(root: ConditionalRoot, mapper: TypeMapper | undefined, forConstraint: boolean, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]): Type {
function getConditionalType(root: ConditionalRoot, mapper: TypeMapper | undefined, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]): Type {
let result;
let extraTypes: Type[] | undefined;
let tailCount = 0;
Expand Down Expand Up @@ -19327,8 +19332,8 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
// there are possible values of the check type that are also possible values of the extends type.
// We use a reverse assignability check as it is less expensive than the comparable relationship
// and avoids false positives of a non-empty intersection check.
if (checkType.flags & TypeFlags.Any || forConstraint && !(inferredExtendsType.flags & TypeFlags.Never) && someType(getPermissiveInstantiation(inferredExtendsType), t => isTypeAssignableTo(t, getPermissiveInstantiation(checkType)))) {
(extraTypes || (extraTypes = [])).push(instantiateType(getTypeFromTypeNode(root.node.trueType), combinedMapper || mapper));
if (checkType.flags & TypeFlags.Any || distributiveConditionalConstraintIdentityStack.length !== 0 && !(inferredExtendsType.flags & TypeFlags.Never) && someType(getPermissiveInstantiation(inferredExtendsType), t => isTypeAssignableTo(t, getPermissiveInstantiation(checkType)))) {
(extraTypes ??= []).push(instantiateType(getTypeFromTypeNode(root.node.trueType), combinedMapper || mapper));
Comment on lines +19335 to +19336
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this is the core of the fix, previously only the first level of nested conditional type (in non tail-recursive scenarios) was including the instantiated true type in its extraTypes (the reasoning behind that is outlined in the comment above and in the #56004 's description)

So now we are including it at all nested levels. In other words - previously the forConstraint was only passed to the direct call of getConditionalTypeInstantiation from getConstraintOfDistributiveConditionalType but now this contextual~ information is used for all nested calls.

I've used a global variable to track this as it's not really feasible today to thread this through instantiateType here.

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Why is it not feasible to thread forConstraint through instantiateType?

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Conditional types could appear just at any deeper level of the instantiated type. It's doable to introduce some kind of InstantiationFlags and pass it down to all called functions etc but it felt more complicated to attempt doing it. It would also be fairly easy to forget to pass that down somewhere.

}
// If falseType is an immediately nested conditional type that isn't distributive or has an
// identical checkType, switch to that type and loop.
Expand Down Expand Up @@ -19451,7 +19456,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
aliasSymbol,
aliasTypeArguments,
};
links.resolvedType = getConditionalType(root, /*mapper*/ undefined, /*forConstraint*/ false);
links.resolvedType = getConditionalType(root, /*mapper*/ undefined);
if (outerTypeParameters) {
root.instantiations = new Map<string, Type>();
root.instantiations.set(getTypeListId(outerTypeParameters), links.resolvedType);
Expand Down Expand Up @@ -20465,26 +20470,37 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
return result;
}

function getConditionalTypeInstantiation(type: ConditionalType, mapper: TypeMapper, forConstraint: boolean, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]): Type {
function getConditionalTypeInstantiation(type: ConditionalType, mapper: TypeMapper, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]): Type {
const root = type.root;
if (root.outerTypeParameters) {
// We are instantiating a conditional type that has one or more type parameters in scope. Apply the
// mapper to the type parameters to produce the effective list of type arguments, and compute the
// instantiation cache key from the type IDs of the type arguments.
const typeArguments = map(root.outerTypeParameters, t => getMappedType(t, mapper));
const id = (forConstraint ? "C" : "") + getTypeListId(typeArguments) + getAliasId(aliasSymbol, aliasTypeArguments);
const forDistributiveConditionalConstraint = distributiveConditionalConstraintIdentityStack.length > 0;
const id = (forDistributiveConditionalConstraint ? "C" : "") + getTypeListId(typeArguments) + getAliasId(aliasSymbol, aliasTypeArguments);
let result = root.instantiations!.get(id);
if (!result) {
if (forDistributiveConditionalConstraint) {
const identity = getRecursionIdentity(type);
if (contains(distributiveConditionalConstraintIdentityStack, identity)) {
return neverType;
}
distributiveConditionalConstraintIdentityStack.push(identity);
}
const newMapper = createTypeMapper(root.outerTypeParameters, typeArguments);
const checkType = root.checkType;
const distributionType = root.isDistributive ? getReducedType(getMappedType(checkType, newMapper)) : undefined;
// Distributive conditional types are distributed over union types. For example, when the
// distributive conditional type T extends U ? X : Y is instantiated with A | B for T, the
// result is (A extends U ? X : Y) | (B extends U ? X : Y).
result = distributionType && checkType !== distributionType && distributionType.flags & (TypeFlags.Union | TypeFlags.Never) ?
mapTypeWithAlias(distributionType, t => getConditionalType(root, prependTypeMapping(checkType, t, newMapper), forConstraint), aliasSymbol, aliasTypeArguments) :
getConditionalType(root, newMapper, forConstraint, aliasSymbol, aliasTypeArguments);
mapTypeWithAlias(distributionType, t => getConditionalType(root, prependTypeMapping(checkType, t, newMapper)), aliasSymbol, aliasTypeArguments) :
getConditionalType(root, newMapper, aliasSymbol, aliasTypeArguments);
root.instantiations!.set(id, result);
if (forDistributiveConditionalConstraint) {
distributiveConditionalConstraintIdentityStack.pop();
}
}
return result;
}
Expand Down Expand Up @@ -20565,7 +20581,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
return getIndexedAccessType(instantiateType((type as IndexedAccessType).objectType, mapper), instantiateType((type as IndexedAccessType).indexType, mapper), (type as IndexedAccessType).accessFlags, /*accessNode*/ undefined, newAliasSymbol, newAliasTypeArguments);
}
if (flags & TypeFlags.Conditional) {
return getConditionalTypeInstantiation(type as ConditionalType, combineTypeMappers((type as ConditionalType).mapper, mapper), /*forConstraint*/ false, aliasSymbol, aliasTypeArguments);
return getConditionalTypeInstantiation(type as ConditionalType, combineTypeMappers((type as ConditionalType).mapper, mapper), aliasSymbol, aliasTypeArguments);
}
if (flags & TypeFlags.Substitution) {
const newBaseType = instantiateType((type as SubstitutionType).baseType, mapper);
Expand Down
24 changes: 2 additions & 22 deletions ...rcularlyConstrainedMappedTypeContainingConditionalNoInfiniteInstantiationDepth.errors.txt
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Original file line number Diff line number Diff line change
@@ -1,15 +1,5 @@
circularlyConstrainedMappedTypeContainingConditionalNoInfiniteInstantiationDepth.ts(63,84): error TS2344: Type 'GetProps<C>' does not satisfy the constraint 'Shared<TInjectedProps, GetProps<C>>'.
Type 'Matching<TInjectedProps, GetProps<C>>' is not assignable to type 'Shared<TInjectedProps, GetProps<C>>'.
Type 'P extends keyof TInjectedProps ? TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : TInjectedProps[P] : GetProps<C>[P]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
Type 'Extract<keyof TInjectedProps, keyof GetProps<C>> extends keyof TInjectedProps ? TInjectedProps[Extract<keyof TInjectedProps, keyof GetProps<C>>] extends GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>] ? GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>] : TInjectedProps[Extract<keyof TInjectedProps, keyof GetProps<C>>] : GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
Type '(Extract<string, keyof GetProps<C>> extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] extends GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] ? GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : GetProps<C>[Extract<string, keyof GetProps<C>>]) | (Extract<number, keyof GetProps<C>> extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & Extract<number, keyof GetProps<C>>] extends GetProps<C>[keyof TInjectedProps & Extract<number, keyof GetProps<C>>] ? GetProps<C>[keyof TInjectedProps & Extract<number, keyof GetProps<C>>] : TInjectedProps[keyof TInjectedProps & Extract<number, keyof GetProps<C>>] : GetProps<C>[Extract<number, keyof GetProps<C>>]) | (Extract<symbol, keyof GetProps<C>> extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & Extract<symbol, keyof GetProps<C>>] extends GetProps<C>[keyof TInjectedProps & Extract<symbol, keyof GetProps<C>>] ? GetProps<C>[keyof TInjectedProps & Extract<symbol, keyof GetProps<C>>] : TInjectedProps[keyof TInjectedProps & Extract<symbol, keyof GetProps<C>>] : GetProps<C>[Extract<symbol, keyof GetProps<C>>])' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
Type 'Extract<string, keyof GetProps<C>> extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] extends GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] ? GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : GetProps<C>[Extract<string, keyof GetProps<C>>]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
Type 'keyof GetProps<C> & string extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string] extends GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] ? GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] : TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string] : GetProps<C>[keyof GetProps<C> & string]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
Type 'string extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & string] extends GetProps<C>[keyof TInjectedProps & string] ? GetProps<C>[keyof TInjectedProps & string] : TInjectedProps[keyof TInjectedProps & string] : GetProps<C>[string]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
Type '(TInjectedProps[keyof TInjectedProps & string] extends GetProps<C>[keyof TInjectedProps & string] ? GetProps<C>[keyof TInjectedProps & string] : TInjectedProps[keyof TInjectedProps & string]) | GetProps<C>[string]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
Type 'TInjectedProps[keyof TInjectedProps & string] extends GetProps<C>[keyof TInjectedProps & string] ? GetProps<C>[keyof TInjectedProps & string] : TInjectedProps[keyof TInjectedProps & string]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
Type 'GetProps<C>[keyof TInjectedProps & string] | TInjectedProps[keyof TInjectedProps & string]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
Type 'GetProps<C>[keyof TInjectedProps & string]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
Type 'unknown' is not assignable to type 'Shared<TInjectedProps, GetProps<C>>'.


==== circularlyConstrainedMappedTypeContainingConditionalNoInfiniteInstantiationDepth.ts (1 errors) ====
Expand Down Expand Up @@ -78,15 +68,5 @@ circularlyConstrainedMappedTypeContainingConditionalNoInfiniteInstantiationDepth
) => ConnectedComponentClass<C, Omit<GetProps<C>, keyof Shared<TInjectedProps, GetProps<C>>> & TNeedsProps>;
~~~~~~~~~~~
!!! error TS2344: Type 'GetProps<C>' does not satisfy the constraint 'Shared<TInjectedProps, GetProps<C>>'.
!!! error TS2344: Type 'Matching<TInjectedProps, GetProps<C>>' is not assignable to type 'Shared<TInjectedProps, GetProps<C>>'.
!!! error TS2344: Type 'P extends keyof TInjectedProps ? TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : TInjectedProps[P] : GetProps<C>[P]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
!!! error TS2344: Type 'Extract<keyof TInjectedProps, keyof GetProps<C>> extends keyof TInjectedProps ? TInjectedProps[Extract<keyof TInjectedProps, keyof GetProps<C>>] extends GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>] ? GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>] : TInjectedProps[Extract<keyof TInjectedProps, keyof GetProps<C>>] : GetProps<C>[Extract<keyof TInjectedProps, keyof GetProps<C>>]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
!!! error TS2344: Type '(Extract<string, keyof GetProps<C>> extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] extends GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] ? GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : GetProps<C>[Extract<string, keyof GetProps<C>>]) | (Extract<number, keyof GetProps<C>> extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & Extract<number, keyof GetProps<C>>] extends GetProps<C>[keyof TInjectedProps & Extract<number, keyof GetProps<C>>] ? GetProps<C>[keyof TInjectedProps & Extract<number, keyof GetProps<C>>] : TInjectedProps[keyof TInjectedProps & Extract<number, keyof GetProps<C>>] : GetProps<C>[Extract<number, keyof GetProps<C>>]) | (Extract<symbol, keyof GetProps<C>> extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & Extract<symbol, keyof GetProps<C>>] extends GetProps<C>[keyof TInjectedProps & Extract<symbol, keyof GetProps<C>>] ? GetProps<C>[keyof TInjectedProps & Extract<symbol, keyof GetProps<C>>] : TInjectedProps[keyof TInjectedProps & Extract<symbol, keyof GetProps<C>>] : GetProps<C>[Extract<symbol, keyof GetProps<C>>])' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
!!! error TS2344: Type 'Extract<string, keyof GetProps<C>> extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] extends GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] ? GetProps<C>[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : TInjectedProps[keyof TInjectedProps & Extract<string, keyof GetProps<C>>] : GetProps<C>[Extract<string, keyof GetProps<C>>]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
!!! error TS2344: Type 'keyof GetProps<C> & string extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string] extends GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] ? GetProps<C>[keyof TInjectedProps & keyof GetProps<C> & string] : TInjectedProps[keyof TInjectedProps & keyof GetProps<C> & string] : GetProps<C>[keyof GetProps<C> & string]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
!!! error TS2344: Type 'string extends keyof TInjectedProps ? TInjectedProps[keyof TInjectedProps & string] extends GetProps<C>[keyof TInjectedProps & string] ? GetProps<C>[keyof TInjectedProps & string] : TInjectedProps[keyof TInjectedProps & string] : GetProps<C>[string]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
!!! error TS2344: Type '(TInjectedProps[keyof TInjectedProps & string] extends GetProps<C>[keyof TInjectedProps & string] ? GetProps<C>[keyof TInjectedProps & string] : TInjectedProps[keyof TInjectedProps & string]) | GetProps<C>[string]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
!!! error TS2344: Type 'TInjectedProps[keyof TInjectedProps & string] extends GetProps<C>[keyof TInjectedProps & string] ? GetProps<C>[keyof TInjectedProps & string] : TInjectedProps[keyof TInjectedProps & string]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
!!! error TS2344: Type 'GetProps<C>[keyof TInjectedProps & string] | TInjectedProps[keyof TInjectedProps & string]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
!!! error TS2344: Type 'GetProps<C>[keyof TInjectedProps & string]' is not assignable to type '(TInjectedProps[P] extends GetProps<C>[P] ? GetProps<C>[P] : never) | undefined'.
!!! error TS2344: Type 'unknown' is not assignable to type 'Shared<TInjectedProps, GetProps<C>>'.

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