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Make spread assignability and apparent type stricter

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Assignability now does not allow properties to the left of a type
parameter.
Apparent type now only returns the apparent type of the right-most
spread member.
This commit is contained in:
Nathan Shively-Sanders 2016-10-19 15:04:30 -07:00
parent 62c186872d
commit a90905358d
1 changed files with 11 additions and 11 deletions
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22
src/compiler/checker.ts
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@ -4515,7 +4515,7 @@ namespace ts {
}
function getApparentTypeOfSpread(type: SpreadType) {
return getSpreadType([getApparentType(type.left), getApparentType(type.right)], type.symbol);
return getApparentType(type.right);
}
/**
@ -5837,9 +5837,8 @@ namespace ts {
left.flags & TypeFlags.Spread &&
(left as SpreadType).right.flags & TypeFlags.ObjectType) {
// simplify two adjacent object types: T ... { x } ... { y } becomes T ... { x, y }
// Note: left.left is always a spread type. Can we use this fact to avoid calling getSpreadType again?
return getSpreadType([getSpreadType([right, (left as SpreadType).right], symbol, aliasSymbol, aliasTypeArguments),
(left as SpreadType).left], symbol, aliasSymbol, aliasTypeArguments);
const simplified = getSpreadType([right, (left as SpreadType).right], symbol, aliasSymbol, aliasTypeArguments);
return getSpreadType([(left as SpreadType).left, simplified], symbol, aliasSymbol, aliasTypeArguments);
}
if (left.flags & TypeFlags.Intersection) {
const spreads = map((left as IntersectionType).types,
@ -6872,7 +6871,7 @@ namespace ts {
if (source.flags & TypeFlags.Spread && target.flags & TypeFlags.Spread) {
// you only see this for spreads with type parameters
if (!(spreadTypeRelatedTo(source as SpreadType, target as SpreadType))) {
if (!(spreadTypeRelatedTo(source as SpreadType, target as SpreadType, /*atRightEdge*/ true))) {
if (reportErrors) {
reportRelationError(headMessage, source, target);
}
@ -6945,13 +6944,14 @@ namespace ts {
return Ternary.False;
}
function spreadTypeRelatedTo(source: SpreadType, target: SpreadType): boolean {
function spreadTypeRelatedTo(source: SpreadType, target: SpreadType, atRightEdge?: boolean): boolean {
// If the right side of a spread type is ObjectType, then the left side must be a Spread.
// Structural compatibility of the spreads' object types are checked separately in isRelatedTo,
// so just skip them for now.
if (source.right.flags & TypeFlags.ObjectType || target.right.flags & TypeFlags.ObjectType) {
return spreadTypeRelatedTo(source.right.flags & TypeFlags.ObjectType ? source.left as SpreadType : source,
target.right.flags & TypeFlags.ObjectType ? target.left as SpreadType : target);
return atRightEdge &&
spreadTypeRelatedTo(source.right.flags & TypeFlags.ObjectType ? source.left as SpreadType : source,
target.right.flags & TypeFlags.ObjectType ? target.left as SpreadType : target);
}
// If both right sides are type parameters, then they must be identical for the spread types to be related.
// It also means that the left sides are either spread types or object types.
@ -6964,9 +6964,9 @@ namespace ts {
// If the left sides are both spread types, then recursively check them.
return spreadTypeRelatedTo(source.left as SpreadType, target.left as SpreadType);
}
// If the left sides are both object types, then isRelatedTo will check the structural compatibility next.
// Otherwise, one side has more type parameters than the other and the spread types are not related.
return !!(source.left.flags & TypeFlags.ObjectType && target.left.flags & TypeFlags.ObjectType);
// If the left sides are both object types, then we should be at the end and both should be emptyObjectType.
// If not, we can't know what properties might have been overwritten, so fail.
return source.left === emptyObjectType && target.left === emptyObjectType;
}
function isIdenticalTo(source: Type, target: Type): Ternary {