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Remove more intersections with empty value domains from union types

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This commit is contained in:
Anders Hejlsberg
2018-04-24 15:55:15 -07:00
parent ef8d5094b4
commit d90d6b9277
2 changed files with 13 additions and 3 deletions
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15
src/compiler/checker.ts
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@@ -7917,8 +7917,13 @@ namespace ts {
return binarySearch(types, type, getTypeId, compareValues) >= 0;
}
// Return true if the given intersection type contains (a) more than one unit type or (b) an object
// type and a nullable type (null or undefined).
// Return true if the given intersection type contains
// more than one unit type or,
// an object type and a nullable type (null or undefined), or
// a string-like type and a non-string-like primitive type, or
// a number-like type and a non-number-like primitive type, or
// a symbol-like type and a non-symbol-like primitive type, or
// a void-like type and a non-void-like primitive type.
function isEmptyIntersectionType(type: IntersectionType) {
let combined: TypeFlags = 0;
for (const t of type.types) {
@@ -7926,7 +7931,11 @@ namespace ts {
return true;
}
combined |= t.flags;
if (combined & TypeFlags.Nullable && combined & (TypeFlags.Object | TypeFlags.NonPrimitive)) {
if (combined & TypeFlags.Nullable && combined & (TypeFlags.Object | TypeFlags.NonPrimitive) ||
combined & TypeFlags.StringLike && combined & (TypeFlags.Primitive & ~TypeFlags.StringLike) ||
combined & TypeFlags.NumberLike && combined & (TypeFlags.Primitive & ~TypeFlags.NumberLike) ||
combined & TypeFlags.ESSymbolLike && combined & (TypeFlags.Primitive & ~TypeFlags.ESSymbolLike) ||
combined & TypeFlags.VoidLike && combined & (TypeFlags.Primitive & ~TypeFlags.VoidLike)) {
return true;
}
}

1
src/compiler/types.ts
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@@ -3613,6 +3613,7 @@ namespace ts {
BooleanLike = Boolean | BooleanLiteral,
EnumLike = Enum | EnumLiteral,
ESSymbolLike = ESSymbol | UniqueESSymbol,
VoidLike = Void | Undefined,
UnionOrIntersection = Union | Intersection,
StructuredType = Object | Union | Intersection,
TypeVariable = TypeParameter | IndexedAccess,