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do not add 'this' type for classes that considered safe (use 'this' only in property\element access expressions) #7474

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d633f7f
do not add 'this' type for classes that considered safe (use 'this' o…
vladima Mar 11, 2016
840efc1
update baselines
vladima Mar 11, 2016
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35 changes: 27 additions & 8 deletions src/compiler/binder.ts
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Expand Up @@ -108,7 +108,7 @@ namespace ts {
let container: Node;
let blockScopeContainer: Node;
let lastContainer: Node;
let seenThisKeyword: boolean;
let usesThisTypeOrReference: boolean;

// state used by reachability checks
let hasExplicitReturn: boolean;
Expand Down Expand Up @@ -152,7 +152,7 @@ namespace ts {
container = undefined;
blockScopeContainer = undefined;
lastContainer = undefined;
seenThisKeyword = false;
usesThisTypeOrReference = false;
hasExplicitReturn = false;
labelStack = undefined;
labelIndexMap = undefined;
Expand Down Expand Up @@ -451,8 +451,17 @@ namespace ts {
// reset all emit helper flags on node (for incremental scenarios)
flags &= ~NodeFlags.EmitHelperFlags;

if (kind === SyntaxKind.InterfaceDeclaration) {
seenThisKeyword = false;
// for classes and interfaces we need to track the usages of 'this' inside the body of declaration
const trackThisOccurences = kind === SyntaxKind.InterfaceDeclaration || isClassLikeKind(kind);
// state of usesThisTypeOrReference should be saved and restored if either
// - trackThisOccurences is true
// - current node is function declaration / function expression - they don't capture lexical this
const needSaveThisState = trackThisOccurences || kind === SyntaxKind.FunctionDeclaration || kind === SyntaxKind.FunctionExpression;
let savedUsesThisTypeOrReference: boolean;

if (needSaveThisState) {
savedUsesThisTypeOrReference = usesThisTypeOrReference;
usesThisTypeOrReference = false;
}

const saveState = kind === SyntaxKind.SourceFile || kind === SyntaxKind.ModuleBlock || isFunctionLikeKind(kind);
Expand Down Expand Up @@ -481,8 +490,11 @@ namespace ts {
}
}

if (kind === SyntaxKind.InterfaceDeclaration) {
flags = seenThisKeyword ? flags | NodeFlags.ContainsThis : flags & ~NodeFlags.ContainsThis;
if (trackThisOccurences) {
flags = usesThisTypeOrReference ? flags | NodeFlags.UsesThisTypeOrReference : flags & ~NodeFlags.UsesThisTypeOrReference;
}
if (needSaveThisState) {
usesThisTypeOrReference = savedUsesThisTypeOrReference;
}

if (kind === SyntaxKind.SourceFile) {
Expand Down Expand Up @@ -1276,8 +1288,15 @@ namespace ts {
return checkStrictModePrefixUnaryExpression(<PrefixUnaryExpression>node);
case SyntaxKind.WithStatement:
return checkStrictModeWithStatement(<WithStatement>node);
case SyntaxKind.ThisKeyword:
if (node.parent.kind !== SyntaxKind.PropertyAccessExpression && node.parent.kind !== SyntaxKind.ElementAccessExpression) {
// property access\element access expressions are considered 'safe' usages of 'this' - 'this' cannot escape the class scope
// in all other cases pessimistically assume that 'this' can escape so class needs special treatment
usesThisTypeOrReference = true;
}
break;
case SyntaxKind.ThisType:
seenThisKeyword = true;
usesThisTypeOrReference = true;
return;
case SyntaxKind.TypePredicate:
return checkTypePredicate(node as TypePredicateNode);
Expand Down Expand Up @@ -1375,7 +1394,7 @@ namespace ts {
checkStrictModeIdentifier(parameterName as Identifier);
}
if (parameterName && parameterName.kind === SyntaxKind.ThisType) {
seenThisKeyword = true;
usesThisTypeOrReference = true;
}
bind(type);
}
Expand Down
110 changes: 82 additions & 28 deletions src/compiler/checker.ts
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Expand Up @@ -825,7 +825,8 @@ namespace ts {
// No static member is present.
// Check if we're in an instance method and look for a relevant instance member.
if (location === container && !(location.flags & NodeFlags.Static)) {
const instanceType = (<InterfaceType>getDeclaredTypeOfSymbol(classSymbol)).thisType;
const declaredType = <InterfaceType>getDeclaredTypeOfSymbol(classSymbol);
const instanceType = declaredType.thisType || declaredType;
if (getPropertyOfType(instanceType, name)) {
error(errorLocation, Diagnostics.Cannot_find_name_0_Did_you_mean_the_instance_member_this_0, typeof nameArg === "string" ? nameArg : declarationNameToString(nameArg));
return true;
Expand Down Expand Up @@ -3328,25 +3329,62 @@ namespace ts {
}
}

// Returns true if the interface given by the symbol is free of "this" references. Specifically, the result is
// true if the interface itself contains no references to "this" in its body, if all base types are interfaces,
// and if none of the base interfaces have a "this" type.
function isIndependentInterface(symbol: Symbol): boolean {
function isIndependentBaseInterfaceList(nodes: NodeArray<ExpressionWithTypeArguments>): boolean {
if (!nodes) {
return true;
}
for (const node of nodes) {
if (!isIndependentHeritageClauseElement(node, /*classSymbol*/ undefined)) {
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Might be worth merging in Ron's every from the transforms branch and making classSymbol optional so you can just say

return !nodes || !every(nodes, isIndependentHeritageClauseElement)

return false;
}
}
return true;
}

function isIndependentHeritageClauseElement(node: ExpressionWithTypeArguments, classSymbol: Symbol): boolean {
if (!node) {
return true;
}
if (isSupportedExpressionWithTypeArguments(node)) {
const baseSymbol = resolveEntityName(node.expression, SymbolFlags.Type, /*ignoreErrors*/ true);
if (!baseSymbol || baseSymbol === unknownSymbol) {
// pessimistically asssume that base type is not independent
return false;
}
const baseType = <InterfaceType>getDeclaredTypeOfSymbol(baseSymbol);
if (baseType.thisType) {
return false;
}
}
else if (classSymbol) {
Debug.assert((classSymbol.flags & SymbolFlags.Class) !== 0);
const baseTypes = getBaseTypes(<InterfaceType>getDeclaredTypeOfClassOrInterface(classSymbol));
if (baseTypes.length) {
return (<InterfaceType>baseTypes[0]).thisType === undefined;
}
}
return true;
}

// Returns true if the class\interface given by the symbol is free of "this" references. Specifically, the result is
// true if the class\interface itself contains no references to "this" in its body, if all base types are classes\interfaces,
// and if none of the base classes\interfaces have a "this" type.
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For interfaces, what if the derived types (if any) have references to this? Wouldn't the base interface need a this type then?

function isIndependentClassOrInterface(symbol: Symbol): boolean {
for (const declaration of symbol.declarations) {
if (declaration.flags & NodeFlags.UsesThisTypeOrReference) {
return false;
}
if (declaration.kind === SyntaxKind.InterfaceDeclaration) {
if (declaration.flags & NodeFlags.ContainsThis) {
if (!isIndependentBaseInterfaceList(getInterfaceBaseTypeNodes(<InterfaceDeclaration>declaration))) {
return false;
}
const baseTypeNodes = getInterfaceBaseTypeNodes(<InterfaceDeclaration>declaration);
if (baseTypeNodes) {
for (const node of baseTypeNodes) {
if (isSupportedExpressionWithTypeArguments(node)) {
const baseSymbol = resolveEntityName(node.expression, SymbolFlags.Type, /*ignoreErrors*/ true);
if (!baseSymbol || !(baseSymbol.flags & SymbolFlags.Interface) || getDeclaredTypeOfClassOrInterface(baseSymbol).thisType) {
return false;
}
}
}
}
else if (isClassLike(declaration)) {
const isIndependent = isIndependentHeritageClauseElement(getClassExtendsHeritageClauseElement(declaration), symbol) &&
isIndependentBaseInterfaceList(getClassImplementsHeritageClauseElements(declaration));

if (!isIndependent) {
return false;
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I think it would be easier to read as

const isIndependentExtends = ...
const isIndependentImplements = ...
return isIndependentExtends && isIndependentImplements;

(The passthrough if (!isIndependent) return false; is a little suspicious because it doesn't do anything special.)

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current version won't check isIndependentImplements if isIndependentExtends parts returns false and suggested version will do both checks

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good point. Maybe just get rid of the if and return directly then?

}
}
}
Expand All @@ -3365,7 +3403,9 @@ namespace ts {
// property types inferred from initializers and method return types inferred from return statements are very hard
// to exhaustively analyze). We give interfaces a "this" type if we can't definitely determine that they are free of
// "this" references.
if (outerTypeParameters || localTypeParameters || kind === TypeFlags.Class || !isIndependentInterface(symbol)) {
const isGeneric = outerTypeParameters || localTypeParameters;
const isIndependent = isIndependentClassOrInterface(symbol);
if (isGeneric || !isIndependent) {
type.flags |= TypeFlags.Reference;
type.typeParameters = concatenate(outerTypeParameters, localTypeParameters);
type.outerTypeParameters = outerTypeParameters;
Expand All @@ -3374,9 +3414,11 @@ namespace ts {
(<GenericType>type).instantiations[getTypeListId(type.typeParameters)] = <GenericType>type;
(<GenericType>type).target = <GenericType>type;
(<GenericType>type).typeArguments = type.typeParameters;
type.thisType = <TypeParameter>createType(TypeFlags.TypeParameter | TypeFlags.ThisType);
type.thisType.symbol = symbol;
type.thisType.constraint = type;
if (!isIndependent) {
type.thisType = <TypeParameter>createType(TypeFlags.TypeParameter | TypeFlags.ThisType);
type.thisType.symbol = symbol;
type.thisType.constraint = type;
}
}
}
return <InterfaceType>links.declaredType;
Expand Down Expand Up @@ -3576,13 +3618,18 @@ namespace ts {
}

function getTypeWithThisArgument(type: ObjectType, thisArgument?: Type) {
if (type.flags & TypeFlags.Reference) {
if (hasAssociatedThisType(type)) {
// instantiate type reference only if type uses thisType
return createTypeReference((<TypeReference>type).target,
concatenate((<TypeReference>type).typeArguments, [thisArgument || (<TypeReference>type).target.thisType]));
}
return type;
}

function hasAssociatedThisType(type: ObjectType): boolean {
return type.flags & TypeFlags.Reference && !!(<TypeReference>type).target.thisType;
}

function resolveObjectTypeMembers(type: ObjectType, source: InterfaceTypeWithDeclaredMembers, typeParameters: TypeParameter[], typeArguments: Type[]) {
let mapper = identityMapper;
let members = source.symbol.members;
Expand All @@ -3592,7 +3639,7 @@ namespace ts {
let numberIndexInfo = source.declaredNumberIndexInfo;
if (!rangeEquals(typeParameters, typeArguments, 0, typeParameters.length)) {
mapper = createTypeMapper(typeParameters, typeArguments);
members = createInstantiatedSymbolTable(source.declaredProperties, mapper, /*mappingThisOnly*/ typeParameters.length === 1);
members = createInstantiatedSymbolTable(source.declaredProperties, mapper, hasAssociatedThisType(type) && typeParameters.length === 1);
callSignatures = instantiateList(source.declaredCallSignatures, mapper, instantiateSignature);
constructSignatures = instantiateList(source.declaredConstructSignatures, mapper, instantiateSignature);
stringIndexInfo = instantiateIndexInfo(source.declaredStringIndexInfo, mapper);
Expand All @@ -3603,9 +3650,11 @@ namespace ts {
if (members === source.symbol.members) {
members = createSymbolTable(source.declaredProperties);
}
const thisArgument = lastOrUndefined(typeArguments);
const thisArgument = hasAssociatedThisType(type) ? lastOrUndefined(typeArguments) : undefined;
for (const baseType of baseTypes) {
const instantiatedBaseType = thisArgument ? getTypeWithThisArgument(instantiateType(baseType, mapper), thisArgument) : baseType;
const instantiatedBaseType = thisArgument
? getTypeWithThisArgument(instantiateType(baseType, mapper), thisArgument)
: instantiateType(baseType, mapper);
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why do we now need to instantiate the baseType with no this argument?

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because baseType might be generic

addInheritedMembers(members, getPropertiesOfObjectType(instantiatedBaseType));
callSignatures = concatenate(callSignatures, getSignaturesOfType(instantiatedBaseType, SignatureKind.Call));
constructSignatures = concatenate(constructSignatures, getSignaturesOfType(instantiatedBaseType, SignatureKind.Construct));
Expand All @@ -3622,7 +3671,7 @@ namespace ts {

function resolveTypeReferenceMembers(type: TypeReference): void {
const source = resolveDeclaredMembers(type.target);
const typeParameters = concatenate(source.typeParameters, [source.thisType]);
const typeParameters = source.thisType ? concatenate(source.typeParameters, [source.thisType]) : source.typeParameters;
const typeArguments = type.typeArguments && type.typeArguments.length === typeParameters.length ?
type.typeArguments : concatenate(type.typeArguments, [type]);
resolveObjectTypeMembers(type, source, typeParameters, typeArguments);
Expand Down Expand Up @@ -4961,7 +5010,8 @@ namespace ts {
if (parent && (isClassLike(parent) || parent.kind === SyntaxKind.InterfaceDeclaration)) {
if (!(container.flags & NodeFlags.Static) &&
(container.kind !== SyntaxKind.Constructor || isNodeDescendentOf(node, (<ConstructorDeclaration>container).body))) {
return getDeclaredTypeOfClassOrInterface(getSymbolOfNode(parent)).thisType;
const declaredType = getDeclaredTypeOfClassOrInterface(getSymbolOfNode(parent));
return declaredType.thisType || declaredType;
}
}
error(node, Diagnostics.A_this_type_is_available_only_in_a_non_static_member_of_a_class_or_interface);
Expand Down Expand Up @@ -5236,7 +5286,7 @@ namespace ts {
const declaration = <DeclarationWithTypeParameters>node;
if (declaration.typeParameters) {
for (const d of declaration.typeParameters) {
if (contains(mappedTypes, getDeclaredTypeOfTypeParameter(d.symbol))) {
if (contains(mappedTypes, getDeclaredTypeOfTypeParameter(getMergedSymbol(d.symbol)))) {
return true;
}
}
Expand Down Expand Up @@ -7637,7 +7687,11 @@ namespace ts {

if (isClassLike(container.parent)) {
const symbol = getSymbolOfNode(container.parent);
return container.flags & NodeFlags.Static ? getTypeOfSymbol(symbol) : (<InterfaceType>getDeclaredTypeOfSymbol(symbol)).thisType;
if (container.flags & NodeFlags.Static) {
return getTypeOfSymbol(symbol);
}
const declaredType = (<InterfaceType>getDeclaredTypeOfSymbol(symbol));
return declaredType.thisType || declaredType;
}

if (isInJavaScriptFile(node)) {
Expand Down
2 changes: 1 addition & 1 deletion src/compiler/types.ts
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Expand Up @@ -387,7 +387,7 @@ namespace ts {
Const = 1 << 11, // Variable declaration
Namespace = 1 << 12, // Namespace declaration
ExportContext = 1 << 13, // Export context (initialized by binding)
ContainsThis = 1 << 14, // Interface contains references to "this"
UsesThisTypeOrReference = 1 << 14, // Class\interface contains references to "this"
HasImplicitReturn = 1 << 15, // If function implicitly returns on one of codepaths (initialized by binding)
HasExplicitReturn = 1 << 16, // If function has explicit reachable return on one of codepaths (initialized by binding)
GlobalAugmentation = 1 << 17, // Set if module declaration is an augmentation for the global scope
Expand Down
6 changes: 5 additions & 1 deletion src/compiler/utilities.ts
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Expand Up @@ -676,7 +676,11 @@ namespace ts {
}

export function isClassLike(node: Node): node is ClassLikeDeclaration {
return node && (node.kind === SyntaxKind.ClassDeclaration || node.kind === SyntaxKind.ClassExpression);
return node && isClassLikeKind(node.kind);
}

export function isClassLikeKind(kind: SyntaxKind): boolean {
return kind === SyntaxKind.ClassDeclaration || kind === SyntaxKind.ClassExpression;
}

export function isFunctionLike(node: Node): node is FunctionLikeDeclaration {
Expand Down
2 changes: 1 addition & 1 deletion tests/baselines/reference/2dArrays.types
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Expand Up @@ -28,7 +28,7 @@ class Board {
>this.ships.every(function (val) { return val.isSunk; }) : boolean
>this.ships.every : (callbackfn: (value: Ship, index: number, array: Ship[]) => boolean, thisArg?: any) => boolean
>this.ships : Ship[]
>this : this
>this : Board
>ships : Ship[]
>every : (callbackfn: (value: Ship, index: number, array: Ship[]) => boolean, thisArg?: any) => boolean
>function (val) { return val.isSunk; } : (val: Ship) => boolean
Expand Down
6 changes: 3 additions & 3 deletions tests/baselines/reference/accessOverriddenBaseClassMember1.types
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Expand Up @@ -15,11 +15,11 @@ class Point {
>"x=" + this.x : string
>"x=" : string
>this.x : number
>this : this
>this : Point
>x : number
>" y=" : string
>this.y : number
>this : this
>this : Point
>y : number
}
}
Expand Down Expand Up @@ -50,7 +50,7 @@ class ColoredPoint extends Point {
>toString : () => string
>" color=" : string
>this.color : string
>this : this
>this : ColoredPoint
>color : string
}
}
Expand Down
2 changes: 1 addition & 1 deletion tests/baselines/reference/aliasUsageInAccessorsOfClass.types
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Expand Up @@ -26,7 +26,7 @@ class C2 {

return this.x;
>this.x : IHasVisualizationModel
>this : this
>this : C2
>x : IHasVisualizationModel
}
set A(x) {
Expand Down
4 changes: 2 additions & 2 deletions tests/baselines/reference/ambiguousCallsWhereReturnTypesAgree.types
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Expand Up @@ -31,7 +31,7 @@ class TestClass {
this.bar(x); // should not error
>this.bar(x) : void
>this.bar : { (x: string): void; (x: string[]): void; }
>this : this
>this : TestClass
>bar : { (x: string): void; (x: string[]): void; }
>x : any
}
Expand Down Expand Up @@ -71,7 +71,7 @@ class TestClass2 {
return this.bar(x); // should not error
>this.bar(x) : number
>this.bar : { (x: string): number; (x: string[]): number; }
>this : this
>this : TestClass2
>bar : { (x: string): number; (x: string[]): number; }
>x : any
}
Expand Down
2 changes: 1 addition & 1 deletion tests/baselines/reference/amdModuleName1.types
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Expand Up @@ -10,7 +10,7 @@ class Foo {
this.x = 5;
>this.x = 5 : number
>this.x : number
>this : this
>this : Foo
>x : number
>5 : number
}
Expand Down
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