microsoft/TypeScript
1
0
Fork 0
mirror of https://github.com/microsoft/TypeScript.git synced 2026-02-06 20:14:01 -06:00
Code Issues Packages Projects Releases 212 Wiki Activity

Reduce intersections with never-typed discriminants to never

Browse Source
This commit is contained in:
Anders Hejlsberg 2020-02-07 13:41:11 -08:00
parent b8b59489e1
commit e601690c83
1 changed files with 35 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

36
src/compiler/checker.ts
View File

@ -12176,6 +12176,9 @@ namespace ts {
UnionReduction.Literal, aliasSymbol, aliasTypeArguments);
}
}
else if (includes & TypeFlags.Object && hasPropertiesWithDisjointTypes(typeSet)) {
result = neverType;
}
else {
result = createIntersectionType(typeSet, aliasSymbol, aliasTypeArguments);
}
@ -12184,6 +12187,38 @@ namespace ts {
return result;
}
function hasPropertiesWithDisjointTypes(typeSet: Type[]) {
const members = createMap<Symbol | Symbol[]>();
for (const type of typeSet) {
if (type.flags & TypeFlags.Object && !isGenericMappedType(type) && !isArrayType(type) && !isTupleType(type)) {
for (const prop of getPropertiesOfObjectType(type)) {
if (prop.flags & SymbolFlags.Property) {
const name = <string>prop.escapedName;
const cached = members.get(name);
if (!cached) {
members.set(name, prop);
}
else if (!isArray(cached)) {
members.set(name, [cached, prop]);
}
else {
cached.push(prop);
}
}
}
}
}
for (const props of arrayFrom(members.values())) {
if (isArray(props)) {
const types = map(props, getTypeOfSymbol);
if (every(types, isLiteralType) && getIntersectionType(types).flags & TypeFlags.Never) {
return true;
}
}
}
return false;
}
function getTypeFromIntersectionTypeNode(node: IntersectionTypeNode): Type {
const links = getNodeLinks(node);
if (!links.resolvedType) {
@ -16256,7 +16291,6 @@ namespace ts {
}
function propertiesRelatedTo(source: Type, target: Type, reportErrors: boolean, excludedProperties: UnderscoreEscapedMap<true> | undefined, intersectionState: IntersectionState): Ternary {
if (relation === identityRelation) {
return propertiesIdenticalTo(source, target, excludedProperties);
}