microsoft/TypeScript
1
0
Fork 0
mirror of https://github.com/microsoft/TypeScript.git synced 2026-02-16 15:44:16 -06:00
Code Issues Packages Projects Releases 212 Wiki Activity

Better algorithm for combined co- and contra-variant inferences.

Browse Source
This commit is contained in:
Anders Hejlsberg 2018-06-12 12:29:29 -07:00
parent dee51ed78b
commit f93f6ec17b
1 changed files with 7 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
src/compiler/checker.ts
View File

@ -11250,7 +11250,7 @@ namespace ts {
if (relation === identityRelation) {
return propertiesIdenticalTo(source, target);
}
const requireOptionalProperties = relation === subtypeRelation && !isObjectLiteralType(source) && !isEmptyArrayLiteralType(source);
const requireOptionalProperties = relation === subtypeRelation && !isObjectLiteralType(source) && !isEmptyArrayLiteralType(source) && !isTupleType(source);
const unmatchedProperty = getUnmatchedProperty(source, target, requireOptionalProperties);
if (unmatchedProperty) {
if (reportErrors) {
@ -12963,17 +12963,14 @@ namespace ts {
if (!inferredType) {
const signature = context.signature;
if (signature) {
if (inference.contraCandidates) {
// If we have contravariant inferences we find the best common subtype and treat
// that as a single covariant candidate.
inference.candidates = append(inference.candidates, getContravariantInference(inference));
inference.contraCandidates = undefined;
}
if (inference.candidates) {
inferredType = getCovariantInference(inference, context, signature);
// If we have inferred 'never' but have contravariant candidates. To get a more specific type we
// infer from the contravariant candidates instead.
if (inferredType.flags & TypeFlags.Never && inference.contraCandidates) {
inferredType = getContravariantInference(inference);
}
}
else if (inference.contraCandidates) {
// We only have contravariant inferences, infer the best common subtype of those
inferredType = getContravariantInference(inference);
}
else if (context.flags & InferenceFlags.NoDefault) {
// We use silentNeverType as the wildcard that signals no inferences.