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Merged
merged 4 commits into from
Aug 29, 2015
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Union subtype reduction #4537

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d8d7fb9
Restoring union type subtype reduction
ahejlsberg Aug 28, 2015
00e7c46
Fixing fourslash tests
ahejlsberg Aug 28, 2015
49bb2bb
Accepting new baselines
ahejlsberg Aug 28, 2015
603eb86
Addressing CR feedback
ahejlsberg Aug 29, 2015
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138 changes: 44 additions & 94 deletions src/compiler/checker.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -3119,7 +3119,7 @@ namespace ts {
}

function resolveTupleTypeMembers(type: TupleType) {
let arrayType = resolveStructuredTypeMembers(createArrayType(getUnionType(type.elementTypes, /*noDeduplication*/ true)));
let arrayType = resolveStructuredTypeMembers(createArrayType(getUnionType(type.elementTypes, /*noSubtypeReduction*/ true)));
let members = createTupleTypeMemberSymbols(type.elementTypes);
addInheritedMembers(members, arrayType.properties);
setObjectTypeMembers(type, members, arrayType.callSignatures, arrayType.constructSignatures, arrayType.stringIndexType, arrayType.numberIndexType);
Expand Down Expand Up @@ -3451,29 +3451,6 @@ namespace ts {
return undefined;
}

// Check if a property with the given name is known anywhere in the given type. In an object
// type, a property is considered known if the object type is empty, if it has any index
// signatures, or if the property is actually declared in the type. In a union or intersection
// type, a property is considered known if it is known in any constituent type.
function isKnownProperty(type: Type, name: string): boolean {
if (type.flags & TypeFlags.ObjectType && type !== globalObjectType) {
const resolved = resolveStructuredTypeMembers(type);
return !!(resolved.properties.length === 0 ||
resolved.stringIndexType ||
resolved.numberIndexType ||
getPropertyOfType(type, name));
}
if (type.flags & TypeFlags.UnionOrIntersection) {
for (let t of (<UnionOrIntersectionType>type).types) {
if (isKnownProperty(t, name)) {
return true;
}
}
return false;
}
return true;
}

function getSignaturesOfStructuredType(type: Type, kind: SignatureKind): Signature[] {
if (type.flags & TypeFlags.StructuredType) {
let resolved = resolveStructuredTypeMembers(<ObjectType>type);
Expand Down Expand Up @@ -4103,73 +4080,20 @@ namespace ts {
}
}

function isObjectLiteralTypeDuplicateOf(source: ObjectType, target: ObjectType): boolean {
let sourceProperties = getPropertiesOfObjectType(source);
let targetProperties = getPropertiesOfObjectType(target);
if (sourceProperties.length !== targetProperties.length) {
return false;
}
for (let sourceProp of sourceProperties) {
let targetProp = getPropertyOfObjectType(target, sourceProp.name);
if (!targetProp ||
getDeclarationFlagsFromSymbol(targetProp) & (NodeFlags.Private | NodeFlags.Protected) ||
!isTypeDuplicateOf(getTypeOfSymbol(sourceProp), getTypeOfSymbol(targetProp))) {
return false;
}
}
return true;
}

function isTupleTypeDuplicateOf(source: TupleType, target: TupleType): boolean {
let sourceTypes = source.elementTypes;
let targetTypes = target.elementTypes;
if (sourceTypes.length !== targetTypes.length) {
return false;
}
for (var i = 0; i < sourceTypes.length; i++) {
if (!isTypeDuplicateOf(sourceTypes[i], targetTypes[i])) {
return false;
}
}
return true;
}

// Returns true if the source type is a duplicate of the target type. A source type is a duplicate of
// a target type if the the two are identical, with the exception that the source type may have null or
// undefined in places where the target type doesn't. This is by design an asymmetric relationship.
function isTypeDuplicateOf(source: Type, target: Type): boolean {
if (source === target) {
return true;
}
if (source.flags & TypeFlags.Undefined || source.flags & TypeFlags.Null && !(target.flags & TypeFlags.Undefined)) {
return true;
}
if (source.flags & TypeFlags.ObjectLiteral && target.flags & TypeFlags.ObjectType) {
return isObjectLiteralTypeDuplicateOf(<ObjectType>source, <ObjectType>target);
}
if (isArrayType(source) && isArrayType(target)) {
return isTypeDuplicateOf((<TypeReference>source).typeArguments[0], (<TypeReference>target).typeArguments[0]);
}
if (isTupleType(source) && isTupleType(target)) {
return isTupleTypeDuplicateOf(<TupleType>source, <TupleType>target);
}
return isTypeIdenticalTo(source, target);
}

function isTypeDuplicateOfSomeType(candidate: Type, types: Type[]): boolean {
for (let type of types) {
if (candidate !== type && isTypeDuplicateOf(candidate, type)) {
function isSubtypeOfAny(candidate: Type, types: Type[]): boolean {
for (var i = 0, len = types.length; i < len; i++) {
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Use let

if (candidate !== types[i] && isTypeSubtypeOf(candidate, types[i])) {
return true;
}
}
return false;
}

function removeDuplicateTypes(types: Type[]) {
let i = types.length;
function removeSubtypes(types: Type[]) {
var i = types.length;
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Use let

while (i > 0) {
i--;
if (isTypeDuplicateOfSomeType(types[i], types)) {
if (isSubtypeOfAny(types[i], types)) {
types.splice(i, 1);
}
}
Expand All @@ -4194,12 +4118,14 @@ namespace ts {
}
}

// We always deduplicate the constituent type set based on object identity, but we'll also deduplicate
// based on the structure of the types unless the noDeduplication flag is true, which is the case when
// creating a union type from a type node and when instantiating a union type. In both of those cases,
// structural deduplication has to be deferred to properly support recursive union types. For example,
// a type of the form "type Item = string | (() => Item)" cannot be deduplicated during its declaration.
function getUnionType(types: Type[], noDeduplication?: boolean): Type {
// We reduce the constituent type set to only include types that aren't subtypes of other types, unless
// the noSubtypeReduction flag is specified, in which case we perform a simple deduplication based on
// object identity. Subtype reduction is possible only when union types are known not to circularly
// reference themselves (as is the case with union types created by expression constructs such as array
// literals and the || and ?: operators). Named types can circularly reference themselves and therefore
// cannot be deduplicated during their declaration. For example, "type Item = string | (() => Item" is
// a named type that circularly references itself.
function getUnionType(types: Type[], noSubtypeReduction?: boolean): Type {
if (types.length === 0) {
return emptyObjectType;
}
Expand All @@ -4208,12 +4134,12 @@ namespace ts {
if (containsTypeAny(typeSet)) {
return anyType;
}
if (noDeduplication) {
if (noSubtypeReduction) {
removeAllButLast(typeSet, undefinedType);
removeAllButLast(typeSet, nullType);
}
else {
removeDuplicateTypes(typeSet);
removeSubtypes(typeSet);
}
if (typeSet.length === 1) {
return typeSet[0];
Expand All @@ -4230,7 +4156,7 @@ namespace ts {
function getTypeFromUnionTypeNode(node: UnionTypeNode): Type {
let links = getNodeLinks(node);
if (!links.resolvedType) {
links.resolvedType = getUnionType(map(node.types, getTypeFromTypeNode), /*noDeduplication*/ true);
links.resolvedType = getUnionType(map(node.types, getTypeFromTypeNode), /*noSubtypeReduction*/ true);
}
return links.resolvedType;
}
Expand Down Expand Up @@ -4526,7 +4452,7 @@ namespace ts {
return createTupleType(instantiateList((<TupleType>type).elementTypes, mapper, instantiateType));
}
if (type.flags & TypeFlags.Union) {
return getUnionType(instantiateList((<UnionType>type).types, mapper, instantiateType), /*noDeduplication*/ true);
return getUnionType(instantiateList((<UnionType>type).types, mapper, instantiateType), /*noSubtypeReduction*/ true);
}
if (type.flags & TypeFlags.Intersection) {
return getIntersectionType(instantiateList((<IntersectionType>type).types, mapper, instantiateType));
Expand Down Expand Up @@ -4813,6 +4739,30 @@ namespace ts {
return Ternary.False;
}

// Check if a property with the given name is known anywhere in the given type. In an object type, a property
// is considered known if the object type is empty and the check is for assignability, if the object type has
// index signatures, or if the property is actually declared in the object type. In a union or intersection
// type, a property is considered known if it is known in any constituent type.
function isKnownProperty(type: Type, name: string): boolean {
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Perhaps isExpectedProperty would better describe this.

if (type.flags & TypeFlags.ObjectType) {
const resolved = resolveStructuredTypeMembers(type);
if (relation === assignableRelation && (type === globalObjectType || resolved.properties.length === 0) ||
resolved.stringIndexType || resolved.numberIndexType || getPropertyOfType(type, name)) {
return true;
}
return false;
}
if (type.flags & TypeFlags.UnionOrIntersection) {
for (let t of (<UnionOrIntersectionType>type).types) {
if (isKnownProperty(t, name)) {
return true;
}
}
return false;
}
return true;
}

function hasExcessProperties(source: FreshObjectLiteralType, target: Type, reportErrors: boolean): boolean {
for (let prop of getPropertiesOfObjectType(source)) {
if (!isKnownProperty(target, prop.name)) {
Expand Down Expand Up @@ -5594,7 +5544,7 @@ namespace ts {
return getWidenedTypeOfObjectLiteral(type);
}
if (type.flags & TypeFlags.Union) {
return getUnionType(map((<UnionType>type).types, getWidenedType));
return getUnionType(map((<UnionType>type).types, getWidenedType), /*noSubtypeReduction*/ true);
}
if (isArrayType(type)) {
return createArrayType(getWidenedType((<TypeReference>type).typeArguments[0]));
Expand Down
44 changes: 22 additions & 22 deletions tests/baselines/reference/arrayBestCommonTypes.types
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Original file line number Diff line number Diff line change
Expand Up @@ -294,8 +294,8 @@ module EmptyTypes {

// Order matters here so test all the variants
var a1 = [{ x: 0, y: 'a' }, { x: 'a', y: 'a' }, { x: anyObj, y: 'a' }];
>a1 : ({ x: number; y: string; } | { x: string; y: string; } | { x: any; y: string; })[]
>[{ x: 0, y: 'a' }, { x: 'a', y: 'a' }, { x: anyObj, y: 'a' }] : ({ x: number; y: string; } | { x: string; y: string; } | { x: any; y: string; })[]
>a1 : { x: any; y: string; }[]
>[{ x: 0, y: 'a' }, { x: 'a', y: 'a' }, { x: anyObj, y: 'a' }] : { x: any; y: string; }[]
>{ x: 0, y: 'a' } : { x: number; y: string; }
>x : number
>0 : number
Expand All @@ -313,8 +313,8 @@ module EmptyTypes {
>'a' : string

var a2 = [{ x: anyObj, y: 'a' }, { x: 0, y: 'a' }, { x: 'a', y: 'a' }];
>a2 : ({ x: any; y: string; } | { x: number; y: string; } | { x: string; y: string; })[]
>[{ x: anyObj, y: 'a' }, { x: 0, y: 'a' }, { x: 'a', y: 'a' }] : ({ x: any; y: string; } | { x: number; y: string; } | { x: string; y: string; })[]
>a2 : { x: any; y: string; }[]
>[{ x: anyObj, y: 'a' }, { x: 0, y: 'a' }, { x: 'a', y: 'a' }] : { x: any; y: string; }[]
>{ x: anyObj, y: 'a' } : { x: any; y: string; }
>x : any
>anyObj : any
Expand All @@ -332,8 +332,8 @@ module EmptyTypes {
>'a' : string

var a3 = [{ x: 0, y: 'a' }, { x: anyObj, y: 'a' }, { x: 'a', y: 'a' }];
>a3 : ({ x: number; y: string; } | { x: any; y: string; } | { x: string; y: string; })[]
>[{ x: 0, y: 'a' }, { x: anyObj, y: 'a' }, { x: 'a', y: 'a' }] : ({ x: number; y: string; } | { x: any; y: string; } | { x: string; y: string; })[]
>a3 : { x: any; y: string; }[]
>[{ x: 0, y: 'a' }, { x: anyObj, y: 'a' }, { x: 'a', y: 'a' }] : { x: any; y: string; }[]
>{ x: 0, y: 'a' } : { x: number; y: string; }
>x : number
>0 : number
Expand Down Expand Up @@ -639,7 +639,7 @@ module NonEmptyTypes {
>x : number
>y : base
>base : base
>[{ x: 7, y: new derived() }, { x: 5, y: new base() }] : ({ x: number; y: derived; } | { x: number; y: base; })[]
>[{ x: 7, y: new derived() }, { x: 5, y: new base() }] : { x: number; y: base; }[]
>{ x: 7, y: new derived() } : { x: number; y: derived; }
>x : number
>7 : number
Expand All @@ -658,7 +658,7 @@ module NonEmptyTypes {
>x : boolean
>y : base
>base : base
>[{ x: true, y: new derived() }, { x: false, y: new base() }] : ({ x: boolean; y: derived; } | { x: boolean; y: base; })[]
>[{ x: true, y: new derived() }, { x: false, y: new base() }] : { x: boolean; y: base; }[]
>{ x: true, y: new derived() } : { x: boolean; y: derived; }
>x : boolean
>true : boolean
Expand Down Expand Up @@ -697,8 +697,8 @@ module NonEmptyTypes {

// Order matters here so test all the variants
var a1 = [{ x: 0, y: 'a' }, { x: 'a', y: 'a' }, { x: anyObj, y: 'a' }];
>a1 : ({ x: number; y: string; } | { x: string; y: string; } | { x: any; y: string; })[]
>[{ x: 0, y: 'a' }, { x: 'a', y: 'a' }, { x: anyObj, y: 'a' }] : ({ x: number; y: string; } | { x: string; y: string; } | { x: any; y: string; })[]
>a1 : { x: any; y: string; }[]
>[{ x: 0, y: 'a' }, { x: 'a', y: 'a' }, { x: anyObj, y: 'a' }] : { x: any; y: string; }[]
>{ x: 0, y: 'a' } : { x: number; y: string; }
>x : number
>0 : number
Expand All @@ -716,8 +716,8 @@ module NonEmptyTypes {
>'a' : string

var a2 = [{ x: anyObj, y: 'a' }, { x: 0, y: 'a' }, { x: 'a', y: 'a' }];
>a2 : ({ x: any; y: string; } | { x: number; y: string; } | { x: string; y: string; })[]
>[{ x: anyObj, y: 'a' }, { x: 0, y: 'a' }, { x: 'a', y: 'a' }] : ({ x: any; y: string; } | { x: number; y: string; } | { x: string; y: string; })[]
>a2 : { x: any; y: string; }[]
>[{ x: anyObj, y: 'a' }, { x: 0, y: 'a' }, { x: 'a', y: 'a' }] : { x: any; y: string; }[]
>{ x: anyObj, y: 'a' } : { x: any; y: string; }
>x : any
>anyObj : any
Expand All @@ -735,8 +735,8 @@ module NonEmptyTypes {
>'a' : string

var a3 = [{ x: 0, y: 'a' }, { x: anyObj, y: 'a' }, { x: 'a', y: 'a' }];
>a3 : ({ x: number; y: string; } | { x: any; y: string; } | { x: string; y: string; })[]
>[{ x: 0, y: 'a' }, { x: anyObj, y: 'a' }, { x: 'a', y: 'a' }] : ({ x: number; y: string; } | { x: any; y: string; } | { x: string; y: string; })[]
>a3 : { x: any; y: string; }[]
>[{ x: 0, y: 'a' }, { x: anyObj, y: 'a' }, { x: 'a', y: 'a' }] : { x: any; y: string; }[]
>{ x: 0, y: 'a' } : { x: number; y: string; }
>x : number
>0 : number
Expand Down Expand Up @@ -769,29 +769,29 @@ module NonEmptyTypes {
>base2 : typeof base2

var b1 = [baseObj, base2Obj, ifaceObj];
>b1 : (base | base2 | iface)[]
>[baseObj, base2Obj, ifaceObj] : (base | base2 | iface)[]
>b1 : iface[]
>[baseObj, base2Obj, ifaceObj] : iface[]
>baseObj : base
>base2Obj : base2
>ifaceObj : iface

var b2 = [base2Obj, baseObj, ifaceObj];
>b2 : (base2 | base | iface)[]
>[base2Obj, baseObj, ifaceObj] : (base2 | base | iface)[]
>b2 : iface[]
>[base2Obj, baseObj, ifaceObj] : iface[]
>base2Obj : base2
>baseObj : base
>ifaceObj : iface

var b3 = [baseObj, ifaceObj, base2Obj];
>b3 : (base | iface | base2)[]
>[baseObj, ifaceObj, base2Obj] : (base | iface | base2)[]
>b3 : iface[]
>[baseObj, ifaceObj, base2Obj] : iface[]
>baseObj : base
>ifaceObj : iface
>base2Obj : base2

var b4 = [ifaceObj, baseObj, base2Obj];
>b4 : (iface | base | base2)[]
>[ifaceObj, baseObj, base2Obj] : (iface | base | base2)[]
>b4 : iface[]
>[ifaceObj, baseObj, base2Obj] : iface[]
>ifaceObj : iface
>baseObj : base
>base2Obj : base2
Expand Down
8 changes: 4 additions & 4 deletions tests/baselines/reference/arrayLiteralWithMultipleBestCommonTypes.types
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Expand Up @@ -36,8 +36,8 @@ var cs = [a, b, c]; // { x: number; y?: number };[]
>c : { x: number; a?: number; }

var ds = [(x: Object) => 1, (x: string) => 2]; // { (x:Object) => number }[]
>ds : (((x: Object) => number) | ((x: string) => number))[]
>[(x: Object) => 1, (x: string) => 2] : (((x: Object) => number) | ((x: string) => number))[]
>ds : ((x: Object) => number)[]
>[(x: Object) => 1, (x: string) => 2] : ((x: Object) => number)[]
>(x: Object) => 1 : (x: Object) => number
>x : Object
>Object : Object
Expand All @@ -47,8 +47,8 @@ var ds = [(x: Object) => 1, (x: string) => 2]; // { (x:Object) => number }[]
>2 : number

var es = [(x: string) => 2, (x: Object) => 1]; // { (x:string) => number }[]
>es : (((x: string) => number) | ((x: Object) => number))[]
>[(x: string) => 2, (x: Object) => 1] : (((x: string) => number) | ((x: Object) => number))[]
>es : ((x: string) => number)[]
>[(x: string) => 2, (x: Object) => 1] : ((x: string) => number)[]
>(x: string) => 2 : (x: string) => number
>x : string
>2 : number
Expand Down
4 changes: 2 additions & 2 deletions tests/baselines/reference/arrayLiteralsWithRecursiveGenerics.types
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Expand Up @@ -77,8 +77,8 @@ var myDerivedList: DerivedList<number>;
>DerivedList : DerivedList<U>

var as = [list, myDerivedList]; // List<number>[]
>as : (List<number> | DerivedList<number>)[]
>[list, myDerivedList] : (List<number> | DerivedList<number>)[]
>as : List<number>[]
>[list, myDerivedList] : List<number>[]
>list : List<number>
>myDerivedList : DerivedList<number>

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