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Increase selectivity of subtype relationship for signatures

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This commit is contained in:
Anders Hejlsberg
2019-12-12 15:58:50 -08:00
parent 71a91763f4
commit b457de4067
1 changed files with 37 additions and 22 deletions
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59
src/compiler/checker.ts
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@@ -183,10 +183,12 @@ namespace ts {
NoTupleBoundsCheck = 1 << 3,
}
const enum CallbackCheck {
None,
Bivariant,
Strict,
const enum SignatureCheckMode {
BivariantCallback = 1 << 0,
StrictCallback = 1 << 1,
IgnoreReturnTypes = 1 << 2,
StrictArity = 1 << 3,
Callback = BivariantCallback | StrictCallback,
}
const enum MappedTypeModifiers {
@@ -13984,7 +13986,7 @@ namespace ts {
function isSignatureAssignableTo(source: Signature,
target: Signature,
ignoreReturnTypes: boolean): boolean {
return compareSignaturesRelated(source, target, CallbackCheck.None, ignoreReturnTypes, /*reportErrors*/ false,
return compareSignaturesRelated(source, target, ignoreReturnTypes ? SignatureCheckMode.IgnoreReturnTypes : 0, /*reportErrors*/ false,
/*errorReporter*/ undefined, /*errorReporter*/ undefined, compareTypesAssignable, /*reportUnreliableMarkers*/ undefined) !== Ternary.False;
}
@@ -14004,8 +14006,7 @@ namespace ts {
*/
function compareSignaturesRelated(source: Signature,
target: Signature,
callbackCheck: CallbackCheck,
ignoreReturnTypes: boolean,
checkMode: SignatureCheckMode,
reportErrors: boolean,
errorReporter: ErrorReporter | undefined,
incompatibleErrorReporter: ((source: Type, target: Type) => void) | undefined,
@@ -14021,7 +14022,8 @@ namespace ts {
}
const targetCount = getParameterCount(target);
if (!hasEffectiveRestParameter(target) && getMinArgumentCount(source) > targetCount) {
if (!hasEffectiveRestParameter(target) &&
(checkMode & SignatureCheckMode.StrictArity ? getParameterCount(source) : getMinArgumentCount(source)) > targetCount) {
return Ternary.False;
}
@@ -14042,7 +14044,7 @@ namespace ts {
}
const kind = target.declaration ? target.declaration.kind : SyntaxKind.Unknown;
const strictVariance = !callbackCheck && strictFunctionTypes && kind !== SyntaxKind.MethodDeclaration &&
const strictVariance = !(checkMode & SignatureCheckMode.Callback) && strictFunctionTypes && kind !== SyntaxKind.MethodDeclaration &&
kind !== SyntaxKind.MethodSignature && kind !== SyntaxKind.Constructor;
let result = Ternary.True;
@@ -14077,14 +14079,14 @@ namespace ts {
// similar to return values, callback parameters are output positions. This means that a Promise<T>,
// where T is used only in callback parameter positions, will be co-variant (as opposed to bi-variant)
// with respect to T.
const sourceSig = callbackCheck ? undefined : getSingleCallSignature(getNonNullableType(sourceType));
const targetSig = callbackCheck ? undefined : getSingleCallSignature(getNonNullableType(targetType));
const sourceSig = checkMode & SignatureCheckMode.Callback ? undefined : getSingleCallSignature(getNonNullableType(sourceType));
const targetSig = checkMode & SignatureCheckMode.Callback ? undefined : getSingleCallSignature(getNonNullableType(targetType));
const callbacks = sourceSig && targetSig && !getTypePredicateOfSignature(sourceSig) && !getTypePredicateOfSignature(targetSig) &&
(getFalsyFlags(sourceType) & TypeFlags.Nullable) === (getFalsyFlags(targetType) & TypeFlags.Nullable);
const related = callbacks ?
// TODO: GH#18217 It will work if they're both `undefined`, but not if only one is
compareSignaturesRelated(targetSig!, sourceSig!, strictVariance ? CallbackCheck.Strict : CallbackCheck.Bivariant, /*ignoreReturnTypes*/ false, reportErrors, errorReporter, incompatibleErrorReporter, compareTypes, reportUnreliableMarkers) :
!callbackCheck && !strictVariance && compareTypes(sourceType, targetType, /*reportErrors*/ false) || compareTypes(targetType, sourceType, reportErrors);
compareSignaturesRelated(targetSig!, sourceSig!, (checkMode & SignatureCheckMode.StrictArity) | (strictVariance ? SignatureCheckMode.StrictCallback : SignatureCheckMode.BivariantCallback), reportErrors, errorReporter, incompatibleErrorReporter, compareTypes, reportUnreliableMarkers) :
!(checkMode & SignatureCheckMode.Callback) && !strictVariance && compareTypes(sourceType, targetType, /*reportErrors*/ false) || compareTypes(targetType, sourceType, reportErrors);
if (!related) {
if (reportErrors) {
errorReporter!(Diagnostics.Types_of_parameters_0_and_1_are_incompatible,
@@ -14096,7 +14098,7 @@ namespace ts {
result &= related;
}
if (!ignoreReturnTypes) {
if (!(checkMode & SignatureCheckMode.IgnoreReturnTypes)) {
// If a signature resolution is already in-flight, skip issuing a circularity error
// here and just use the `any` type directly
const targetReturnType = isResolvingReturnTypeOfSignature(target) ? anyType
@@ -14127,7 +14129,7 @@ namespace ts {
// When relating callback signatures, we still need to relate return types bi-variantly as otherwise
// the containing type wouldn't be co-variant. For example, interface Foo<T> { add(cb: () => T): void }
// wouldn't be co-variant for T without this rule.
result &= callbackCheck === CallbackCheck.Bivariant && compareTypes(targetReturnType, sourceReturnType, /*reportErrors*/ false) ||
result &= checkMode & SignatureCheckMode.BivariantCallback && compareTypes(targetReturnType, sourceReturnType, /*reportErrors*/ false) ||
compareTypes(sourceReturnType, targetReturnType, reportErrors);
if (!result && reportErrors && incompatibleErrorReporter) {
incompatibleErrorReporter(sourceReturnType, targetReturnType);
@@ -14299,7 +14301,7 @@ namespace ts {
return true;
}
if (source.flags & TypeFlags.Object && target.flags & TypeFlags.Object) {
const related = relation.get(getRelationKey(source, target, /*isIntersectionConstituent*/ false, relation));
const related = relation.get(getRelationKey(source, target, /*isIntersectionConstituent*/ false, /*strictArityChecks*/ false, relation));
if (related !== undefined) {
return !!(related & RelationComparisonResult.Succeeded);
}
@@ -14351,6 +14353,7 @@ namespace ts {
let depth = 0;
let expandingFlags = ExpandingFlags.None;
let overflow = false;
let strictArityChecks = relation === subtypeRelation;
let overrideNextErrorInfo = 0; // How many `reportRelationError` calls should be skipped in the elaboration pyramid
let lastSkippedInfo: [Type, Type] | undefined;
let incompatibleStack: [DiagnosticMessage, (string | number)?, (string | number)?, (string | number)?, (string | number)?][] = [];
@@ -15139,7 +15142,7 @@ namespace ts {
if (overflow) {
return Ternary.False;
}
const id = getRelationKey(source, target, isIntersectionConstituent, relation);
const id = getRelationKey(source, target, isIntersectionConstituent, strictArityChecks, relation);
const entry = relation.get(id);
if (entry !== undefined) {
if (reportErrors && entry & RelationComparisonResult.Failed && !(entry & RelationComparisonResult.Reported)) {
@@ -15486,6 +15489,17 @@ namespace ts {
// to X. Failing both of those we want to check if the aggregation of A and B's members structurally
// relates to X. Thus, we include intersection types on the source side here.
if (source.flags & (TypeFlags.Object | TypeFlags.Intersection) && target.flags & TypeFlags.Object) {
// When performing strict arity checks for signatures (under the subtype relationship), if source has
// every property of target, and target is missing some properties from source, then we disable strict
// arity checks for the members. This decreases the chances of "ties" in union subtype reduction. For
// example, it enables us to consider { f(): void } a supertype of { f(x?: string): void, g(): void },
// which we need for backwards compatibility reasons (specifically, for Object and Number).
const saveStrictArityChecks = strictArityChecks;
if (strictArityChecks &&
!getUnmatchedProperty(source, target, /*requireOptionalProperties*/ true, /*matchDiscriminantProperties*/ false) &&
getUnmatchedProperty(target, source, /*requireOptionalProperties*/ true, /*matchDiscriminantProperties*/ false)) {
strictArityChecks = false;
}
// Report structural errors only if we haven't reported any errors yet
const reportStructuralErrors = reportErrors && errorInfo === saveErrorInfo.errorInfo && !sourceIsPrimitive;
result = propertiesRelatedTo(source, target, reportStructuralErrors, /*excludedProperties*/ undefined, isIntersectionConstituent);
@@ -15501,6 +15515,7 @@ namespace ts {
}
}
}
strictArityChecks = saveStrictArityChecks;
if (varianceCheckFailed && result) {
errorInfo = originalErrorInfo || errorInfo || saveErrorInfo.errorInfo; // Use variance error (there is no structural one) and return false
}
@@ -16045,7 +16060,7 @@ namespace ts {
*/
function signatureRelatedTo(source: Signature, target: Signature, erase: boolean, reportErrors: boolean, incompatibleReporter: (source: Type, target: Type) => void): Ternary {
return compareSignaturesRelated(erase ? getErasedSignature(source) : source, erase ? getErasedSignature(target) : target,
CallbackCheck.None, /*ignoreReturnTypes*/ false, reportErrors, reportError, incompatibleReporter, isRelatedTo, reportUnreliableMarkers);
strictArityChecks ? SignatureCheckMode.StrictArity : 0, reportErrors, reportError, incompatibleReporter, isRelatedTo, reportUnreliableMarkers);
}
function signaturesIdenticalTo(source: Type, target: Type, kind: SignatureKind): Ternary {
@@ -16353,18 +16368,18 @@ namespace ts {
* To improve caching, the relation key for two generic types uses the target's id plus ids of the type parameters.
* For other cases, the types ids are used.
*/
function getRelationKey(source: Type, target: Type, isIntersectionConstituent: boolean, relation: Map<RelationComparisonResult>) {
function getRelationKey(source: Type, target: Type, isIntersectionConstituent: boolean, strictArityChecks: boolean, relation: Map<RelationComparisonResult>) {
if (relation === identityRelation && source.id > target.id) {
const temp = source;
source = target;
target = temp;
}
const intersection = isIntersectionConstituent ? "&" : "";
const delimiter = isIntersectionConstituent ? strictArityChecks ? "|" : ";" : strictArityChecks ? "/" : ",";
if (isTypeReferenceWithGenericArguments(source) && isTypeReferenceWithGenericArguments(target)) {
const typeParameters: Type[] = [];
return getTypeReferenceId(<TypeReference>source, typeParameters) + "," + getTypeReferenceId(<TypeReference>target, typeParameters) + intersection;
return getTypeReferenceId(<TypeReference>source, typeParameters) + delimiter + getTypeReferenceId(<TypeReference>target, typeParameters);
}
return source.id + "," + target.id + intersection;
return source.id + delimiter + target.id;
}
// Invoke the callback for each underlying property symbol of the given symbol and return the first