Typed 'this' in object literal methods

src/compiler/checker.ts

@@ -257,6 +257,7 @@ namespace ts {
  let globalNumberType: ObjectType;
  let globalBooleanType: ObjectType;
  let globalRegExpType: ObjectType;
+ let globalThisType: GenericType;
  let anyArrayType: Type;
  let autoArrayType: Type;
  let anyReadonlyArrayType: Type;
@@ -6040,6 +6041,11 @@ namespace ts {
  return deferredGlobalIterableIteratorType || (deferredGlobalIterableIteratorType = getGlobalType("IterableIterator", /*arity*/ 1, reportErrors)) || emptyGenericType;
  }
 
+ function getGlobalTypeOrUndefined(name: string, arity = 0): ObjectType {
+ const symbol = getGlobalSymbol(name, SymbolFlags.Type, /*diagnostic*/ undefined);
+ return symbol && <GenericType>getTypeOfGlobalSymbol(symbol, arity);
+ }
+
  /**
  * Returns a type that is inside a namespace at the global scope, e.g.
  * getExportedTypeFromNamespace('JSX', 'Element') returns the JSX.Element type
@@ -8977,11 +8983,19 @@ namespace ts {
  return regularNew;
  }
 
+ function getWidenedProperty(prop: Symbol): Symbol {
+ const original = getTypeOfSymbol(prop);
+ const widened = getWidenedType(original);
+ return widened === original ? prop : createSymbolWithType(prop, widened);
+ }
+
  function getWidenedTypeOfObjectLiteral(type: Type): Type {
- const members = transformTypeOfMembers(type, prop => {
- const widened = getWidenedType(prop);
- return prop === widened ? prop : widened;
- });
+ const members = createMap<Symbol>();
+ for (const prop of getPropertiesOfObjectType(type)) {
+ // Since get accessors already widen their return value there is no need to
+ // widen accessor based properties here.
+ members.set(prop.name, prop.flags & SymbolFlags.Property ? getWidenedProperty(prop) : prop);
+ };
  const stringIndexInfo = getIndexInfoOfType(type, IndexKind.String);
  const numberIndexInfo = getIndexInfoOfType(type, IndexKind.Number);
  return createAnonymousType(type.symbol, members, emptyArray, emptyArray,
@@ -11464,8 +11478,29 @@ namespace ts {
  }
  }
 
+ function getContainingObjectLiteral(func: FunctionLikeDeclaration) {
+ return (func.kind === SyntaxKind.MethodDeclaration ||
+ func.kind === SyntaxKind.GetAccessor ||
+ func.kind === SyntaxKind.SetAccessor) && func.parent.kind === SyntaxKind.ObjectLiteralExpression ? <ObjectLiteralExpression>func.parent :
+ func.kind === SyntaxKind.FunctionExpression && func.parent.kind === SyntaxKind.PropertyAssignment ? <ObjectLiteralExpression>func.parent.parent :
+ undefined;
+ }
+
+ function getThisTypeArgument(type: Type): Type {
+ return getObjectFlags(type) & ObjectFlags.Reference && (<TypeReference>type).target === globalThisType ? (<TypeReference>type).typeArguments[0] : undefined;
+ }
+
+ function getThisTypeFromContextualType(type: Type): Type {
+ return applyToContextualType(type, t => {
+ return t.flags & TypeFlags.Intersection ? forEach((<IntersectionType>t).types, getThisTypeArgument) : getThisTypeArgument(t);
+ });
+ }
+
  function getContextualThisParameterType(func: FunctionLikeDeclaration): Type {
- if (isContextSensitiveFunctionOrObjectLiteralMethod(func) && func.kind !== SyntaxKind.ArrowFunction) {
+ if (func.kind === SyntaxKind.ArrowFunction) {
+ return undefined;
+ }
+ if (isContextSensitiveFunctionOrObjectLiteralMethod(func)) {
  const contextualSignature = getContextualSignature(func);
  if (contextualSignature) {
  const thisParameter = contextualSignature.thisParameter;
@@ -11474,6 +11509,37 @@ namespace ts {
  }
  }
  }
+ const containingLiteral = getContainingObjectLiteral(func);
+ if (containingLiteral) {
+ // We have an object literal method. Check if the containing object literal has a contextual type
+ // and if that contextual type is or includes a ThisType<T>. If so, T is the contextual type for
+ // 'this'. We continue looking in any directly enclosing object literals.
+ let objectLiteral = containingLiteral;
+ while (true) {
+ const type = getApparentTypeOfContextualType(objectLiteral);
+ if (type) {
+ const thisType = getThisTypeFromContextualType(type);
+ if (thisType) {
+ return thisType;
+ }
+ }
+ if (objectLiteral.parent.kind !== SyntaxKind.PropertyAssignment) {
+ break;
+ }
+ objectLiteral = <ObjectLiteralExpression>objectLiteral.parent.parent;
+ }
+ // There was no contextual ThisType<T> for the containing object literal, so the contextual type
+ // for 'this' is the type of the object literal itself.
+ return checkExpressionCached(containingLiteral);
+ }
+ // In an assignment of the form 'obj.xxx = function(...)' or 'obj[xxx] = function(...)', the
+ // contextual type for 'this' is 'obj'.
+ if (func.parent.kind === SyntaxKind.BinaryExpression && (<BinaryExpression>func.parent).operatorToken.kind === SyntaxKind.EqualsToken) {
+ const target = (<BinaryExpression>func.parent).left;
+ if (target.kind === SyntaxKind.PropertyAccessExpression || target.kind === SyntaxKind.ElementAccessExpression) {
+ return checkExpressionCached((<PropertyAccessExpression | ElementAccessExpression>target).expression);
+ }
+ }
  return undefined;
  }
 
@@ -12234,7 +12300,7 @@ namespace ts {
  // A set accessor declaration is processed in the same manner
  // as an ordinary function declaration with a single parameter and a Void return type.
  Debug.assert(memberDecl.kind === SyntaxKind.GetAccessor || memberDecl.kind === SyntaxKind.SetAccessor);
- checkAccessorDeclaration(<AccessorDeclaration>memberDecl);
+ checkNodeDeferred(memberDecl);
  }
 
  if (hasDynamicName(memberDecl)) {
@@ -16889,13 +16955,8 @@ namespace ts {
  checkAllCodePathsInNonVoidFunctionReturnOrThrow(node, returnType);
  }
  }
- if (node.parent.kind !== SyntaxKind.ObjectLiteralExpression) {
- checkSourceElement(node.body);
- registerForUnusedIdentifiersCheck(node);
- }
- else {
- checkNodeDeferred(node);
- }
+ checkSourceElement(node.body);
+ registerForUnusedIdentifiersCheck(node);
  }
 
  function checkAccessorDeclarationTypesIdentical(first: AccessorDeclaration, second: AccessorDeclaration, getAnnotatedType: (a: AccessorDeclaration) => Type, message: DiagnosticMessage) {
@@ -16906,11 +16967,6 @@ namespace ts {
  }
  }
 
- function checkAccessorDeferred(node: AccessorDeclaration) {
- checkSourceElement(node.body);
- registerForUnusedIdentifiersCheck(node);
- }
-
  function checkMissingDeclaration(node: Node) {
  checkDecorators(node);
  }
@@ -20577,7 +20633,7 @@ namespace ts {
  break;
  case SyntaxKind.GetAccessor:
  case SyntaxKind.SetAccessor:
- checkAccessorDeferred(<AccessorDeclaration>node);
+ checkAccessorDeclaration(<AccessorDeclaration>node);
  break;
  case SyntaxKind.ClassExpression:
  checkClassExpressionDeferred(<ClassExpression>node);
@@ -21921,9 +21977,9 @@ namespace ts {
  anyArrayType = createArrayType(anyType);
  autoArrayType = createArrayType(autoType);
 
- const symbol = getGlobalSymbol("ReadonlyArray", SymbolFlags.Type, /*diagnostic*/ undefined);
- globalReadonlyArrayType = symbol && <GenericType>getTypeOfGlobalSymbol(symbol, /*arity*/ 1);
+ globalReadonlyArrayType = <GenericType>getGlobalTypeOrUndefined("ReadonlyArray", /*arity*/ 1);
  anyReadonlyArrayType = globalReadonlyArrayType ? createTypeFromGenericGlobalType(globalReadonlyArrayType, [anyType]) : anyArrayType;
+ globalThisType = <GenericType>getGlobalTypeOrUndefined("ThisType", /*arity*/ 1);
  }
 
  function checkExternalEmitHelpers(location: Node, helpers: ExternalEmitHelpers) {

src/lib/es5.d.ts

@@ -1366,6 +1366,11 @@ type Record<K extends string, T> = {
  [P in K]: T;
 }
 
+/**
+ * Marker for contextual 'this' type
+ */
+interface ThisType<T> { }
+
 /**
  * Represents a raw buffer of binary data, which is used to store data for the
  * different typed arrays. ArrayBuffers cannot be read from or written to directly,

tests/baselines/reference/castTest.symbols

@@ -71,7 +71,13 @@ var p_cast = <Point> ({
 
  return new Point(this.x + dx, this.y + dy);
 >Point : Symbol(Point, Decl(castTest.ts, 11, 37))
+>this.x : Symbol(x, Decl(castTest.ts, 22, 23))
+>this : Symbol(__object, Decl(castTest.ts, 22, 22))
+>x : Symbol(x, Decl(castTest.ts, 22, 23))
 >dx : Symbol(dx, Decl(castTest.ts, 25, 18))
+>this.y : Symbol(y, Decl(castTest.ts, 23, 9))
+>this : Symbol(__object, Decl(castTest.ts, 22, 22))
+>y : Symbol(y, Decl(castTest.ts, 23, 9))
 >dy : Symbol(dy, Decl(castTest.ts, 25, 21))
 
  },

tests/baselines/reference/castTest.types

@@ -91,15 +91,15 @@ var p_cast = <Point> ({
  return new Point(this.x + dx, this.y + dy);
 >new Point(this.x + dx, this.y + dy) : Point
 >Point : typeof Point
->this.x + dx : any
->this.x : any
->this : any
->x : any
+>this.x + dx : number
+>this.x : number
+>this : { x: number; y: number; add: (dx: number, dy: number) => Point; mult: (p: Point) => Point; }
+>x : number
 >dx : number
->this.y + dy : any
->this.y : any
->this : any
->y : any
+>this.y + dy : number
+>this.y : number
+>this : { x: number; y: number; add: (dx: number, dy: number) => Point; mult: (p: Point) => Point; }
+>y : number
 >dy : number
 
  },

tests/baselines/reference/commentsOnObjectLiteral2.errors.txt

@@ -1,7 +1,8 @@
 tests/cases/compiler/commentsOnObjectLiteral2.ts(1,14): error TS2304: Cannot find name 'makeClass'.
+tests/cases/compiler/commentsOnObjectLiteral2.ts(9,17): error TS2339: Property 'name' does not exist on type '{ initialize: (name: any) => void; }'.
 
 
-==== tests/cases/compiler/commentsOnObjectLiteral2.ts (1 errors) ====
+==== tests/cases/compiler/commentsOnObjectLiteral2.ts (2 errors) ====
  var Person = makeClass( 
  ~~~~~~~~~
 !!! error TS2304: Cannot find name 'makeClass'.
@@ -13,6 +14,8 @@ tests/cases/compiler/commentsOnObjectLiteral2.ts(1,14): error TS2304: Cannot fin
  */ 
  initialize: function(name) { 
  this.name = name; 
+ ~~~~
+!!! error TS2339: Property 'name' does not exist on type '{ initialize: (name: any) => void; }'.
  } /* trailing comment 1*/, 
  } 
  );

tests/baselines/reference/commentsOnObjectLiteral3.symbols

@@ -21,13 +21,20 @@ var v = {
 >a : Symbol(a, Decl(commentsOnObjectLiteral3.ts, 8, 13), Decl(commentsOnObjectLiteral3.ts, 12, 18))
 
  return this.prop;
+>this.prop : Symbol(prop, Decl(commentsOnObjectLiteral3.ts, 1, 9))
+>this : Symbol(v, Decl(commentsOnObjectLiteral3.ts, 1, 7))
+>prop : Symbol(prop, Decl(commentsOnObjectLiteral3.ts, 1, 9))
+
  } /*trailing 1*/,
  //setter
  set a(value) {
 >a : Symbol(a, Decl(commentsOnObjectLiteral3.ts, 8, 13), Decl(commentsOnObjectLiteral3.ts, 12, 18))
 >value : Symbol(value, Decl(commentsOnObjectLiteral3.ts, 14, 7))
 
  this.prop = value;
+>this.prop : Symbol(prop, Decl(commentsOnObjectLiteral3.ts, 1, 9))
+>this : Symbol(v, Decl(commentsOnObjectLiteral3.ts, 1, 7))
+>prop : Symbol(prop, Decl(commentsOnObjectLiteral3.ts, 1, 9))
 >value : Symbol(value, Decl(commentsOnObjectLiteral3.ts, 14, 7))
 
  } // trailing 2

tests/baselines/reference/commentsOnObjectLiteral3.types

@@ -1,8 +1,8 @@
 === tests/cases/compiler/commentsOnObjectLiteral3.ts ===
 
 var v = {
->v : { prop: number; func: () => void; func1(): void; a: any; }
->{ //property prop: 1 /* multiple trailing comments */ /*trailing comments*/, //property func: function () { }, //PropertyName + CallSignature func1() { }, //getter get a() { return this.prop; } /*trailing 1*/, //setter set a(value) { this.prop = value; } // trailing 2} : { prop: number; func: () => void; func1(): void; a: any; }
+>v : { prop: number; func: () => void; func1(): void; a: number; }
+>{ //property prop: 1 /* multiple trailing comments */ /*trailing comments*/, //property func: function () { }, //PropertyName + CallSignature func1() { }, //getter get a() { return this.prop; } /*trailing 1*/, //setter set a(value) { this.prop = value; } // trailing 2} : { prop: number; func: () => void; func1(): void; a: number; }
 
  //property
  prop: 1 /* multiple trailing comments */ /*trailing comments*/,
@@ -21,25 +21,25 @@ var v = {
 
  //getter
  get a() {
->a : any
+>a : number
 
  return this.prop;
->this.prop : any
->this : any
->prop : any
+>this.prop : number
+>this : { prop: number; func: () => void; func1(): void; a: number; }
+>prop : number
 
  } /*trailing 1*/,
  //setter
  set a(value) {
->a : any
->value : any
+>a : number
+>value : number
 
  this.prop = value;
->this.prop = value : any
->this.prop : any
->this : any
->prop : any
->value : any
+>this.prop = value : number
+>this.prop : number
+>this : { prop: number; func: () => void; func1(): void; a: number; }
+>prop : number
+>value : number
 
  } // trailing 2
 };

tests/baselines/reference/declFileObjectLiteralWithAccessors.symbols

@@ -15,6 +15,9 @@ function /*1*/makePoint(x: number) {
  set x(a: number) { this.b = a; }
 >x : Symbol(x, Decl(declFileObjectLiteralWithAccessors.ts, 3, 14), Decl(declFileObjectLiteralWithAccessors.ts, 4, 30))
 >a : Symbol(a, Decl(declFileObjectLiteralWithAccessors.ts, 5, 14))
+>this.b : Symbol(b, Decl(declFileObjectLiteralWithAccessors.ts, 2, 12))
+>this : Symbol(__object, Decl(declFileObjectLiteralWithAccessors.ts, 2, 10))
+>b : Symbol(b, Decl(declFileObjectLiteralWithAccessors.ts, 2, 12))
 >a : Symbol(a, Decl(declFileObjectLiteralWithAccessors.ts, 5, 14))
 
  };

tests/baselines/reference/declFileObjectLiteralWithAccessors.types

@@ -19,9 +19,9 @@ function /*1*/makePoint(x: number) {
 >x : number
 >a : number
 >this.b = a : number
->this.b : any
->this : any
->b : any
+>this.b : number
+>this : { b: number; x: number; }
+>b : number
 >a : number
 
  };

tests/baselines/reference/declFileObjectLiteralWithOnlySetter.symbols

@@ -11,6 +11,9 @@ function /*1*/makePoint(x: number) {
  set x(a: number) { this.b = a; }
 >x : Symbol(x, Decl(declFileObjectLiteralWithOnlySetter.ts, 3, 14))
 >a : Symbol(a, Decl(declFileObjectLiteralWithOnlySetter.ts, 4, 14))
+>this.b : Symbol(b, Decl(declFileObjectLiteralWithOnlySetter.ts, 2, 12))
+>this : Symbol(__object, Decl(declFileObjectLiteralWithOnlySetter.ts, 2, 10))
+>b : Symbol(b, Decl(declFileObjectLiteralWithOnlySetter.ts, 2, 12))
 >a : Symbol(a, Decl(declFileObjectLiteralWithOnlySetter.ts, 4, 14))
 
  };

tests/baselines/reference/declFileObjectLiteralWithOnlySetter.types

@@ -15,9 +15,9 @@ function /*1*/makePoint(x: number) {
 >x : number
 >a : number
 >this.b = a : number
->this.b : any
->this : any
->b : any
+>this.b : number
+>this : { b: number; x: number; }
+>b : number
 >a : number
 
  };

tests/baselines/reference/declarationEmitThisPredicates02.errors.txt

@@ -13,7 +13,7 @@ tests/cases/conformance/declarationEmit/typePredicates/declarationEmitThisPredic
  m(): this is Foo {
  ~~~~
 !!! error TS2526: A 'this' type is available only in a non-static member of a class or interface.
- let dis = this as Foo;
+ let dis = this as {} as Foo;
  return dis.a != null && dis.b != null && dis.c != null;
  }
  }

tests/baselines/reference/declarationEmitThisPredicates02.js

@@ -8,7 +8,7 @@ export interface Foo {
 
 export const obj = {
  m(): this is Foo {
- let dis = this as Foo;
+ let dis = this as {} as Foo;
  return dis.a != null && dis.b != null && dis.c != null;
  }
 }

tests/baselines/reference/declarationEmitThisPredicatesWithPrivateName02.errors.txt

@@ -16,7 +16,7 @@ tests/cases/conformance/declarationEmit/typePredicates/declarationEmitThisPredic
  m(): this is Foo {
  ~~~~
 !!! error TS2526: A 'this' type is available only in a non-static member of a class or interface.
- let dis = this as Foo;
+ let dis = this as {} as Foo;
  return dis.a != null && dis.b != null && dis.c != null;
  }
  }

tests/baselines/reference/declarationEmitThisPredicatesWithPrivateName02.js

@@ -8,7 +8,7 @@ interface Foo {
 
 export const obj = {
  m(): this is Foo {
- let dis = this as Foo;
+ let dis = this as {} as Foo;
  return dis.a != null && dis.b != null && dis.c != null;
  }
 }