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Tail recursive evaluation of conditional types (#45711)
* Implement tail-recursion for conditional types and lower general instantiation depth limit to 100 * Add tests * Skip caching for tail recursive temporary conditional types
This commit is contained in:
Anders Hejlsberg
GitHub
parent
4f5bbd00e6
commit
b9eeb74f37
@ -15265,10 +15265,18 @@ namespace ts {
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function getConditionalType(root: ConditionalRoot, mapper: TypeMapper | undefined, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]): Type {
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let result;
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let extraTypes: Type[] | undefined;
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let tailCount = 0;
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// We loop here for an immediately nested conditional type in the false position, effectively treating
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// types of the form 'A extends B ? X : C extends D ? Y : E extends F ? Z : ...' as a single construct for
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// purposes of resolution. This means such types aren't subject to the instantiation depth limiter.
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// purposes of resolution. We also loop here when resolution of a conditional type ends in resolution of
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// another (or, through recursion, possibly the same) conditional type. In the potentially tail-recursive
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// cases we increment the tail recursion counter and stop after 1000 iterations.
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while (true) {
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if (tailCount === 1000) {
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error(currentNode, Diagnostics.Type_instantiation_is_excessively_deep_and_possibly_infinite);
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result = errorType;
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break;
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}
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const isUnwrapped = isTypicalNondistributiveConditional(root);
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const checkType = instantiateType(unwrapNondistributiveConditionalTuple(root, getActualTypeVariable(root.checkType)), mapper);
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const checkTypeInstantiable = isGenericType(checkType);
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@ -15312,6 +15320,9 @@ namespace ts {
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root = newRoot;
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continue;
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}
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if (canTailRecurse(falseType, mapper)) {
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continue;
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}
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}
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result = instantiateType(falseType, mapper);
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break;
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@ -15322,7 +15333,12 @@ namespace ts {
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// type Foo<T extends { x: any }> = T extends { x: string } ? string : number
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// doesn't immediately resolve to 'string' instead of being deferred.
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if (inferredExtendsType.flags & TypeFlags.AnyOrUnknown || isTypeAssignableTo(getRestrictiveInstantiation(checkType), getRestrictiveInstantiation(inferredExtendsType))) {
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result = instantiateType(getTypeFromTypeNode(root.node.trueType), combinedMapper || mapper);
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const trueType = getTypeFromTypeNode(root.node.trueType);
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const trueMapper = combinedMapper || mapper;
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if (canTailRecurse(trueType, trueMapper)) {
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continue;
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}
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result = instantiateType(trueType, trueMapper);
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break;
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}
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}
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@ -15338,6 +15354,32 @@ namespace ts {
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break;
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}
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return extraTypes ? getUnionType(append(extraTypes, result)) : result;
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// We tail-recurse for generic conditional types that (a) have not already been evaluated and cached, and
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// (b) are non distributive, have a check type that is unaffected by instantiation, or have a non-union check
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// type. Note that recursion is possible only through aliased conditional types, so we only increment the tail
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// recursion counter for those.
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function canTailRecurse(newType: Type, newMapper: TypeMapper | undefined) {
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if (newType.flags & TypeFlags.Conditional && newMapper) {
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const newRoot = (newType as ConditionalType).root;
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if (newRoot.outerTypeParameters) {
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const typeParamMapper = combineTypeMappers((newType as ConditionalType).mapper, newMapper);
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const typeArguments = map(newRoot.outerTypeParameters, t => getMappedType(t, typeParamMapper));
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const newRootMapper = createTypeMapper(newRoot.outerTypeParameters, typeArguments);
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const newCheckType = newRoot.isDistributive ? getMappedType(newRoot.checkType, newRootMapper) : undefined;
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if (!newCheckType || newCheckType === newRoot.checkType || !(newCheckType.flags & (TypeFlags.Union | TypeFlags.Never))) {
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root = newRoot;
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mapper = newRootMapper;
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aliasSymbol = undefined;
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aliasTypeArguments = undefined;
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if (newRoot.aliasSymbol) {
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tailCount++;
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}
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return true;
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}
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}
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}
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return false;
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}
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}
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function getTrueTypeFromConditionalType(type: ConditionalType) {
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@ -16358,8 +16400,8 @@ namespace ts {
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if (!couldContainTypeVariables(type)) {
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return type;
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}
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if (instantiationDepth === 500 || instantiationCount >= 5000000) {
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// We have reached 500 recursive type instantiations, or 5M type instantiations caused by the same statement
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if (instantiationDepth === 100 || instantiationCount >= 5000000) {
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// We have reached 100 recursive type instantiations, or 5M type instantiations caused by the same statement
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// or expression. There is a very high likelyhood we're dealing with a combination of infinite generic types
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// that perpetually generate new type identities, so we stop the recursion here by yielding the error type.
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tracing?.instant(tracing.Phase.CheckTypes, "instantiateType_DepthLimit", { typeId: type.id, instantiationDepth, instantiationCount });
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49
tests/baselines/reference/tailRecursiveConditionalTypes.js
Normal file
49
tests/baselines/reference/tailRecursiveConditionalTypes.js
Normal file
@ -0,0 +1,49 @@
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//// [tailRecursiveConditionalTypes.ts]
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type Trim<S extends string> =
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S extends ` ${infer T}` ? Trim<T> :
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S extends `${infer T} ` ? Trim<T> :
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S;
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type T10 = Trim<' hello '>;
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type T11 = Trim<' hello '>;
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type GetChars<S> = GetCharsRec<S, never>;
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type GetCharsRec<S, Acc> =
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S extends `${infer Char}${infer Rest}` ? GetCharsRec<Rest, Char | Acc> : Acc;
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type T20 = GetChars<'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789'>;
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type Reverse<T> = any[] extends T ? T : ReverseRec<T, []>;
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type ReverseRec<T, Acc extends unknown[]> =
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T extends [infer Head, ...infer Tail] ? ReverseRec<Tail, [Head, ...Acc]> : Acc;
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type T30 = Reverse<[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9]>;
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type T31 = Reverse<string[]>;
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type TupleOf<T, N extends number> = number extends N ? T[] : TupleOfRec<T, N, []>;
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type TupleOfRec<T, N extends number, Acc extends unknown[]> =
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Acc["length"] extends N ? Acc : TupleOfRec<T, N, [T, ...Acc]>;
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type T40 = TupleOf<any, 200>;
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type T41 = TupleOf<any, number>;
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//// [tailRecursiveConditionalTypes.js]
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"use strict";
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//// [tailRecursiveConditionalTypes.d.ts]
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declare type Trim<S extends string> = S extends ` ${infer T}` ? Trim<T> : S extends `${infer T} ` ? Trim<T> : S;
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declare type T10 = Trim<' hello '>;
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declare type T11 = Trim<' hello '>;
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declare type GetChars<S> = GetCharsRec<S, never>;
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declare type GetCharsRec<S, Acc> = S extends `${infer Char}${infer Rest}` ? GetCharsRec<Rest, Char | Acc> : Acc;
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declare type T20 = GetChars<'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789'>;
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declare type Reverse<T> = any[] extends T ? T : ReverseRec<T, []>;
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declare type ReverseRec<T, Acc extends unknown[]> = T extends [infer Head, ...infer Tail] ? ReverseRec<Tail, [Head, ...Acc]> : Acc;
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declare type T30 = Reverse<[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9]>;
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declare type T31 = Reverse<string[]>;
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declare type TupleOf<T, N extends number> = number extends N ? T[] : TupleOfRec<T, N, []>;
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declare type TupleOfRec<T, N extends number, Acc extends unknown[]> = Acc["length"] extends N ? Acc : TupleOfRec<T, N, [T, ...Acc]>;
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declare type T40 = TupleOf<any, 200>;
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declare type T41 = TupleOf<any, number>;
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118
tests/baselines/reference/tailRecursiveConditionalTypes.symbols
Normal file
118
tests/baselines/reference/tailRecursiveConditionalTypes.symbols
Normal file
@ -0,0 +1,118 @@
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=== tests/cases/compiler/tailRecursiveConditionalTypes.ts ===
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type Trim<S extends string> =
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>Trim : Symbol(Trim, Decl(tailRecursiveConditionalTypes.ts, 0, 0))
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>S : Symbol(S, Decl(tailRecursiveConditionalTypes.ts, 0, 10))
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S extends ` ${infer T}` ? Trim<T> :
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>S : Symbol(S, Decl(tailRecursiveConditionalTypes.ts, 0, 10))
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>T : Symbol(T, Decl(tailRecursiveConditionalTypes.ts, 1, 23))
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>Trim : Symbol(Trim, Decl(tailRecursiveConditionalTypes.ts, 0, 0))
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>T : Symbol(T, Decl(tailRecursiveConditionalTypes.ts, 1, 23))
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S extends `${infer T} ` ? Trim<T> :
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>S : Symbol(S, Decl(tailRecursiveConditionalTypes.ts, 0, 10))
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>T : Symbol(T, Decl(tailRecursiveConditionalTypes.ts, 2, 22))
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>Trim : Symbol(Trim, Decl(tailRecursiveConditionalTypes.ts, 0, 0))
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>T : Symbol(T, Decl(tailRecursiveConditionalTypes.ts, 2, 22))
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S;
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>S : Symbol(S, Decl(tailRecursiveConditionalTypes.ts, 0, 10))
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type T10 = Trim<' hello '>;
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>T10 : Symbol(T10, Decl(tailRecursiveConditionalTypes.ts, 3, 6))
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>Trim : Symbol(Trim, Decl(tailRecursiveConditionalTypes.ts, 0, 0))
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type T11 = Trim<' hello '>;
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>T11 : Symbol(T11, Decl(tailRecursiveConditionalTypes.ts, 5, 170))
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>Trim : Symbol(Trim, Decl(tailRecursiveConditionalTypes.ts, 0, 0))
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type GetChars<S> = GetCharsRec<S, never>;
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>GetChars : Symbol(GetChars, Decl(tailRecursiveConditionalTypes.ts, 6, 170))
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>S : Symbol(S, Decl(tailRecursiveConditionalTypes.ts, 8, 14))
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>GetCharsRec : Symbol(GetCharsRec, Decl(tailRecursiveConditionalTypes.ts, 8, 41))
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>S : Symbol(S, Decl(tailRecursiveConditionalTypes.ts, 8, 14))
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type GetCharsRec<S, Acc> =
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>GetCharsRec : Symbol(GetCharsRec, Decl(tailRecursiveConditionalTypes.ts, 8, 41))
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>S : Symbol(S, Decl(tailRecursiveConditionalTypes.ts, 9, 17))
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>Acc : Symbol(Acc, Decl(tailRecursiveConditionalTypes.ts, 9, 19))
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S extends `${infer Char}${infer Rest}` ? GetCharsRec<Rest, Char | Acc> : Acc;
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>S : Symbol(S, Decl(tailRecursiveConditionalTypes.ts, 9, 17))
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>Char : Symbol(Char, Decl(tailRecursiveConditionalTypes.ts, 10, 22))
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>Rest : Symbol(Rest, Decl(tailRecursiveConditionalTypes.ts, 10, 35))
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>GetCharsRec : Symbol(GetCharsRec, Decl(tailRecursiveConditionalTypes.ts, 8, 41))
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>Rest : Symbol(Rest, Decl(tailRecursiveConditionalTypes.ts, 10, 35))
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>Char : Symbol(Char, Decl(tailRecursiveConditionalTypes.ts, 10, 22))
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>Acc : Symbol(Acc, Decl(tailRecursiveConditionalTypes.ts, 9, 19))
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>Acc : Symbol(Acc, Decl(tailRecursiveConditionalTypes.ts, 9, 19))
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type T20 = GetChars<'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789'>;
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>T20 : Symbol(T20, Decl(tailRecursiveConditionalTypes.ts, 10, 81))
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>GetChars : Symbol(GetChars, Decl(tailRecursiveConditionalTypes.ts, 6, 170))
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type Reverse<T> = any[] extends T ? T : ReverseRec<T, []>;
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>Reverse : Symbol(Reverse, Decl(tailRecursiveConditionalTypes.ts, 12, 86))
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>T : Symbol(T, Decl(tailRecursiveConditionalTypes.ts, 14, 13))
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>T : Symbol(T, Decl(tailRecursiveConditionalTypes.ts, 14, 13))
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>T : Symbol(T, Decl(tailRecursiveConditionalTypes.ts, 14, 13))
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>ReverseRec : Symbol(ReverseRec, Decl(tailRecursiveConditionalTypes.ts, 14, 58))
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>T : Symbol(T, Decl(tailRecursiveConditionalTypes.ts, 14, 13))
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type ReverseRec<T, Acc extends unknown[]> =
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>ReverseRec : Symbol(ReverseRec, Decl(tailRecursiveConditionalTypes.ts, 14, 58))
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>T : Symbol(T, Decl(tailRecursiveConditionalTypes.ts, 15, 16))
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>Acc : Symbol(Acc, Decl(tailRecursiveConditionalTypes.ts, 15, 18))
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T extends [infer Head, ...infer Tail] ? ReverseRec<Tail, [Head, ...Acc]> : Acc;
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>T : Symbol(T, Decl(tailRecursiveConditionalTypes.ts, 15, 16))
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>Head : Symbol(Head, Decl(tailRecursiveConditionalTypes.ts, 16, 20))
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>Tail : Symbol(Tail, Decl(tailRecursiveConditionalTypes.ts, 16, 35))
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>ReverseRec : Symbol(ReverseRec, Decl(tailRecursiveConditionalTypes.ts, 14, 58))
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>Tail : Symbol(Tail, Decl(tailRecursiveConditionalTypes.ts, 16, 35))
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>Head : Symbol(Head, Decl(tailRecursiveConditionalTypes.ts, 16, 20))
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>Acc : Symbol(Acc, Decl(tailRecursiveConditionalTypes.ts, 15, 18))
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>Acc : Symbol(Acc, Decl(tailRecursiveConditionalTypes.ts, 15, 18))
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type T30 = Reverse<[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9]>;
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>T30 : Symbol(T30, Decl(tailRecursiveConditionalTypes.ts, 16, 83))
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>Reverse : Symbol(Reverse, Decl(tailRecursiveConditionalTypes.ts, 12, 86))
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type T31 = Reverse<string[]>;
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>T31 : Symbol(T31, Decl(tailRecursiveConditionalTypes.ts, 18, 171))
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>Reverse : Symbol(Reverse, Decl(tailRecursiveConditionalTypes.ts, 12, 86))
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type TupleOf<T, N extends number> = number extends N ? T[] : TupleOfRec<T, N, []>;
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>TupleOf : Symbol(TupleOf, Decl(tailRecursiveConditionalTypes.ts, 19, 29))
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>T : Symbol(T, Decl(tailRecursiveConditionalTypes.ts, 21, 13))
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>N : Symbol(N, Decl(tailRecursiveConditionalTypes.ts, 21, 15))
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>N : Symbol(N, Decl(tailRecursiveConditionalTypes.ts, 21, 15))
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>T : Symbol(T, Decl(tailRecursiveConditionalTypes.ts, 21, 13))
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>TupleOfRec : Symbol(TupleOfRec, Decl(tailRecursiveConditionalTypes.ts, 21, 82))
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>T : Symbol(T, Decl(tailRecursiveConditionalTypes.ts, 21, 13))
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>N : Symbol(N, Decl(tailRecursiveConditionalTypes.ts, 21, 15))
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type TupleOfRec<T, N extends number, Acc extends unknown[]> =
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>TupleOfRec : Symbol(TupleOfRec, Decl(tailRecursiveConditionalTypes.ts, 21, 82))
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>T : Symbol(T, Decl(tailRecursiveConditionalTypes.ts, 22, 16))
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>N : Symbol(N, Decl(tailRecursiveConditionalTypes.ts, 22, 18))
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>Acc : Symbol(Acc, Decl(tailRecursiveConditionalTypes.ts, 22, 36))
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Acc["length"] extends N ? Acc : TupleOfRec<T, N, [T, ...Acc]>;
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>Acc : Symbol(Acc, Decl(tailRecursiveConditionalTypes.ts, 22, 36))
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>N : Symbol(N, Decl(tailRecursiveConditionalTypes.ts, 22, 18))
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>Acc : Symbol(Acc, Decl(tailRecursiveConditionalTypes.ts, 22, 36))
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>TupleOfRec : Symbol(TupleOfRec, Decl(tailRecursiveConditionalTypes.ts, 21, 82))
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>T : Symbol(T, Decl(tailRecursiveConditionalTypes.ts, 22, 16))
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>N : Symbol(N, Decl(tailRecursiveConditionalTypes.ts, 22, 18))
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>T : Symbol(T, Decl(tailRecursiveConditionalTypes.ts, 22, 16))
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>Acc : Symbol(Acc, Decl(tailRecursiveConditionalTypes.ts, 22, 36))
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type T40 = TupleOf<any, 200>;
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>T40 : Symbol(T40, Decl(tailRecursiveConditionalTypes.ts, 23, 66))
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>TupleOf : Symbol(TupleOf, Decl(tailRecursiveConditionalTypes.ts, 19, 29))
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type T41 = TupleOf<any, number>;
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>T41 : Symbol(T41, Decl(tailRecursiveConditionalTypes.ts, 25, 29))
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>TupleOf : Symbol(TupleOf, Decl(tailRecursiveConditionalTypes.ts, 19, 29))
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@ -0,0 +1,53 @@
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=== tests/cases/compiler/tailRecursiveConditionalTypes.ts ===
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type Trim<S extends string> =
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>Trim : Trim<S>
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S extends ` ${infer T}` ? Trim<T> :
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S extends `${infer T} ` ? Trim<T> :
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S;
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type T10 = Trim<' hello '>;
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>T10 : "hello"
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type T11 = Trim<' hello '>;
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>T11 : "hello"
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type GetChars<S> = GetCharsRec<S, never>;
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>GetChars : GetChars<S>
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type GetCharsRec<S, Acc> =
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>GetCharsRec : GetCharsRec<S, Acc>
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S extends `${infer Char}${infer Rest}` ? GetCharsRec<Rest, Char | Acc> : Acc;
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type T20 = GetChars<'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789'>;
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>T20 : "A" | "B" | "C" | "D" | "E" | "F" | "G" | "H" | "I" | "J" | "K" | "L" | "M" | "N" | "O" | "P" | "Q" | "R" | "S" | "T" | "U" | "V" | "W" | "X" | "Y" | "Z" | "a" | "b" | "c" | "d" | "e" | "f" | "g" | "h" | "i" | "j" | "k" | "l" | "m" | "n" | "o" | "p" | "q" | "r" | "s" | "t" | "u" | "v" | "w" | "x" | "y" | "z" | "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9"
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type Reverse<T> = any[] extends T ? T : ReverseRec<T, []>;
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>Reverse : Reverse<T>
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type ReverseRec<T, Acc extends unknown[]> =
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>ReverseRec : ReverseRec<T, Acc>
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T extends [infer Head, ...infer Tail] ? ReverseRec<Tail, [Head, ...Acc]> : Acc;
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type T30 = Reverse<[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9]>;
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>T30 : [9, 8, 7, 6, 5, 4, 3, 2, 1, 0, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0]
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type T31 = Reverse<string[]>;
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>T31 : string[]
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type TupleOf<T, N extends number> = number extends N ? T[] : TupleOfRec<T, N, []>;
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>TupleOf : TupleOf<T, N>
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type TupleOfRec<T, N extends number, Acc extends unknown[]> =
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>TupleOfRec : TupleOfRec<T, N, Acc>
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Acc["length"] extends N ? Acc : TupleOfRec<T, N, [T, ...Acc]>;
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type T40 = TupleOf<any, 200>;
|
||||
>T40 : [any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any, any]
|
||||
|
||||
type T41 = TupleOf<any, number>;
|
||||
>T41 : any[]
|
||||
|
||||
30
tests/cases/compiler/tailRecursiveConditionalTypes.ts
Normal file
30
tests/cases/compiler/tailRecursiveConditionalTypes.ts
Normal file
@ -0,0 +1,30 @@
|
||||
// @strict: true
|
||||
// @declaration: true
|
||||
|
||||
type Trim<S extends string> =
|
||||
S extends ` ${infer T}` ? Trim<T> :
|
||||
S extends `${infer T} ` ? Trim<T> :
|
||||
S;
|
||||
|
||||
type T10 = Trim<' hello '>;
|
||||
type T11 = Trim<' hello '>;
|
||||
|
||||
type GetChars<S> = GetCharsRec<S, never>;
|
||||
type GetCharsRec<S, Acc> =
|
||||
S extends `${infer Char}${infer Rest}` ? GetCharsRec<Rest, Char | Acc> : Acc;
|
||||
|
||||
type T20 = GetChars<'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789'>;
|
||||
|
||||
type Reverse<T> = any[] extends T ? T : ReverseRec<T, []>;
|
||||
type ReverseRec<T, Acc extends unknown[]> =
|
||||
T extends [infer Head, ...infer Tail] ? ReverseRec<Tail, [Head, ...Acc]> : Acc;
|
||||
|
||||
type T30 = Reverse<[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9]>;
|
||||
type T31 = Reverse<string[]>;
|
||||
|
||||
type TupleOf<T, N extends number> = number extends N ? T[] : TupleOfRec<T, N, []>;
|
||||
type TupleOfRec<T, N extends number, Acc extends unknown[]> =
|
||||
Acc["length"] extends N ? Acc : TupleOfRec<T, N, [T, ...Acc]>;
|
||||
|
||||
type T40 = TupleOf<any, 200>;
|
||||
type T41 = TupleOf<any, number>;
|
||||
Loading…
x
Reference in New Issue
Block a user