Bind alias ThisProperty assignment declarations (#39908)

* Bind alias ThisProperty assignment declarations

This is a quick prototype that does the wrong thing at the wrong time
with the wrong technique.

* Preliminary checker handling for aliases

Duplicative and untested, but I think I updated all the places that need
updating.

* new is error; old one should not have been removed

* I don't even know what's happening with this test

* cleanup and testing in the checker

* binder: use lookupSymbolForNameWorker instead of mutable

This should have about the same behaviour and is much easier to
understand.

Also refactor common code a bit.

* Shorter name of lookupSymbolForName

Once upon a time there was a parent/worker function, but now it's just a
single function again. No need for the -Worker suffix.

* remove oodate comment

* fix switch-case-break lint

* Refactor and move functions

* Rename and improve type of getContextualTypeForAssignmentDeclaration

Author: sandersn

src/compiler/binder.ts

@@ -2462,7 +2462,7 @@ namespace ts {
                     if (isInJSFile(expr) &&
                         file.commonJsModuleIndicator &&
                         isModuleExportsAccessExpression(expr) &&
-                        !lookupSymbolForNameWorker(blockScopeContainer, "module" as __String)) {
+                        !lookupSymbolForName(blockScopeContainer, "module" as __String)) {
                         declareSymbol(file.locals!, /*parent*/ undefined, expr.expression,
                             SymbolFlags.FunctionScopedVariable | SymbolFlags.ModuleExports, SymbolFlags.FunctionScopedVariableExcludes);
                     }
@@ -2486,6 +2486,14 @@ namespace ts {
                             bindThisPropertyAssignment(node as BindablePropertyAssignmentExpression);
                             break;
                         case AssignmentDeclarationKind.Property:
+                            const expression = ((node as BinaryExpression).left as AccessExpression).expression;
+                            if (isIdentifier(expression)) {
+                                const symbol = lookupSymbolForName(blockScopeContainer, expression.escapedText);
+                                if (isThisInitializedDeclaration(symbol?.valueDeclaration)) {
+                                    bindThisPropertyAssignment(node as BindablePropertyAssignmentExpression);
+                                    break;
+                                }
+                            }
                             bindSpecialPropertyAssignment(node as BindablePropertyAssignmentExpression);
                             break;
                         case AssignmentDeclarationKind.None:
@@ -3104,7 +3112,7 @@ namespace ts {
 
         function lookupSymbolForPropertyAccess(node: BindableStaticNameExpression, lookupContainer: Node = container): Symbol | undefined {
             if (isIdentifier(node)) {
-                return lookupSymbolForNameWorker(lookupContainer, node.escapedText);
+                return lookupSymbolForName(lookupContainer, node.escapedText);
             }
             else {
                 const symbol = lookupSymbolForPropertyAccess(node.expression);
@@ -3404,7 +3412,7 @@ namespace ts {
                 return true;
             }
             else if (isIdentifier(node)) {
-                const symbol = lookupSymbolForNameWorker(sourceFile, node.escapedText);
+                const symbol = lookupSymbolForName(sourceFile, node.escapedText);
                 if (!!symbol && !!symbol.valueDeclaration && isVariableDeclaration(symbol.valueDeclaration) && !!symbol.valueDeclaration.initializer) {
                     const init = symbol.valueDeclaration.initializer;
                     q.push(init);
@@ -3418,7 +3426,7 @@ namespace ts {
         return false;
     }
 
-    function lookupSymbolForNameWorker(container: Node, name: __String): Symbol | undefined {
+    function lookupSymbolForName(container: Node, name: __String): Symbol | undefined {
         const local = container.locals && container.locals.get(name);
         if (local) {
             return local.exportSymbol || local;

src/compiler/checker.ts

@@ -7896,9 +7896,10 @@ namespace ts {
             if (symbol.valueDeclaration && isBinaryExpression(symbol.valueDeclaration)) {
                 const links = getSymbolLinks(symbol);
                 if (links.isConstructorDeclaredProperty === undefined) {
+                    links.isConstructorDeclaredProperty = false;
                     links.isConstructorDeclaredProperty = !!getDeclaringConstructor(symbol) && every(symbol.declarations, declaration =>
                         isBinaryExpression(declaration) &&
-                        getAssignmentDeclarationKind(declaration) === AssignmentDeclarationKind.ThisProperty &&
+                        isPossiblyAliasedThisProperty(declaration) &&
                         (declaration.left.kind !== SyntaxKind.ElementAccessExpression || isStringOrNumericLiteralLike((<ElementAccessExpression>declaration.left).argumentExpression)) &&
                         !getAnnotatedTypeForAssignmentDeclaration(/*declaredType*/ undefined, declaration, symbol, declaration));
                 }
@@ -7975,7 +7976,7 @@ namespace ts {
                     const kind = isAccessExpression(expression)
                         ? getAssignmentDeclarationPropertyAccessKind(expression)
                         : getAssignmentDeclarationKind(expression);
-                    if (kind === AssignmentDeclarationKind.ThisProperty) {
+                    if (kind === AssignmentDeclarationKind.ThisProperty || isBinaryExpression(expression) && isPossiblyAliasedThisProperty(expression, kind)) {
                         if (isDeclarationInConstructor(expression)) {
                             definedInConstructor = true;
                         }
@@ -9637,7 +9638,7 @@ namespace ts {
                     for (const member of decls) {
                         const assignmentKind = getAssignmentDeclarationKind(member as BinaryExpression | CallExpression);
                         const isInstanceMember = assignmentKind === AssignmentDeclarationKind.PrototypeProperty
-                            || assignmentKind === AssignmentDeclarationKind.ThisProperty
+                            || isBinaryExpression(member) && isPossiblyAliasedThisProperty(member, assignmentKind)
                             || assignmentKind === AssignmentDeclarationKind.ObjectDefinePrototypeProperty
                             || assignmentKind === AssignmentDeclarationKind.Prototype; // A straight `Prototype` assignment probably can never have a computed name
                         if (isStatic === !isInstanceMember && hasLateBindableName(member)) {
@@ -23125,14 +23126,7 @@ namespace ts {
                 case SyntaxKind.AmpersandAmpersandEqualsToken:
                 case SyntaxKind.BarBarEqualsToken:
                 case SyntaxKind.QuestionQuestionEqualsToken:
-                    if (node !== right) {
-                        return undefined;
-                    }
-                    const contextSensitive = getIsContextSensitiveAssignmentOrContextType(binaryExpression);
-                    if (!contextSensitive) {
-                        return undefined;
-                    }
-                    return contextSensitive === true ? getTypeOfExpression(left) : contextSensitive;
+                    return node === right ? getContextualTypeForAssignmentDeclaration(binaryExpression) : undefined;
                 case SyntaxKind.BarBarToken:
                 case SyntaxKind.QuestionQuestionToken:
                     // When an || expression has a contextual type, the operands are contextually typed by that type, except
@@ -23153,24 +23147,27 @@ namespace ts {
 
         // In an assignment expression, the right operand is contextually typed by the type of the left operand.
         // Don't do this for assignment declarations unless there is a type tag on the assignment, to avoid circularity from checking the right operand.
-        function getIsContextSensitiveAssignmentOrContextType(binaryExpression: BinaryExpression): boolean | Type {
+        function getContextualTypeForAssignmentDeclaration(binaryExpression: BinaryExpression): Type | undefined {
             const kind = getAssignmentDeclarationKind(binaryExpression);
             switch (kind) {
                 case AssignmentDeclarationKind.None:
-                    return true;
+                    return getTypeOfExpression(binaryExpression.left);
                 case AssignmentDeclarationKind.Property:
                 case AssignmentDeclarationKind.ExportsProperty:
                 case AssignmentDeclarationKind.Prototype:
                 case AssignmentDeclarationKind.PrototypeProperty:
+                    if (isPossiblyAliasedThisProperty(binaryExpression, kind)) {
+                        return getContextualTypeForThisPropertyAssignment(binaryExpression, kind);
+                    }
                     // If `binaryExpression.left` was assigned a symbol, then this is a new declaration; otherwise it is an assignment to an existing declaration.
                     // See `bindStaticPropertyAssignment` in `binder.ts`.
-                    if (!binaryExpression.left.symbol) {
-                        return true;
+                    else if (!binaryExpression.left.symbol) {
+                        return getTypeOfExpression(binaryExpression.left);
                     }
                     else {
                         const decl = binaryExpression.left.symbol.valueDeclaration;
                         if (!decl) {
-                            return false;
+                            return undefined;
                         }
                         const lhs = cast(binaryExpression.left, isAccessExpression);
                         const overallAnnotation = getEffectiveTypeAnnotationNode(decl);
@@ -23185,35 +23182,17 @@ namespace ts {
                                 if (annotated) {
                                     const nameStr = getElementOrPropertyAccessName(lhs);
                                     if (nameStr !== undefined) {
-                                        const type = getTypeOfPropertyOfContextualType(getTypeFromTypeNode(annotated), nameStr);
-                                        return type || false;
+                                        return getTypeOfPropertyOfContextualType(getTypeFromTypeNode(annotated), nameStr);
                                     }
                                 }
-                                return false;
+                                return undefined;
                             }
                         }
-                        return !isInJSFile(decl);
+                        return isInJSFile(decl) ? undefined : getTypeOfExpression(binaryExpression.left);
                     }
                 case AssignmentDeclarationKind.ModuleExports:
                 case AssignmentDeclarationKind.ThisProperty:
-                    if (!binaryExpression.symbol) return true;
-                    if (binaryExpression.symbol.valueDeclaration) {
-                        const annotated = getEffectiveTypeAnnotationNode(binaryExpression.symbol.valueDeclaration);
-                        if (annotated) {
-                            const type = getTypeFromTypeNode(annotated);
-                            if (type) {
-                                return type;
-                            }
-                        }
-                    }
-                    if (kind === AssignmentDeclarationKind.ModuleExports) return false;
-                    const thisAccess = cast(binaryExpression.left, isAccessExpression);
-                    if (!isObjectLiteralMethod(getThisContainer(thisAccess.expression, /*includeArrowFunctions*/ false))) {
-                        return false;
-                    }
-                    const thisType = checkThisExpression(thisAccess.expression);
-                    const nameStr = getElementOrPropertyAccessName(thisAccess);
-                    return nameStr !== undefined && thisType && getTypeOfPropertyOfContextualType(thisType, nameStr) || false;
+                    return getContextualTypeForThisPropertyAssignment(binaryExpression, kind);
                 case AssignmentDeclarationKind.ObjectDefinePropertyValue:
                 case AssignmentDeclarationKind.ObjectDefinePropertyExports:
                 case AssignmentDeclarationKind.ObjectDefinePrototypeProperty:
@@ -23223,6 +23202,40 @@ namespace ts {
             }
         }
 
+        function isPossiblyAliasedThisProperty(declaration: BinaryExpression, kind = getAssignmentDeclarationKind(declaration)) {
+            if (kind === AssignmentDeclarationKind.ThisProperty) {
+                return true;
+            }
+            if (!isInJSFile(declaration) || kind !== AssignmentDeclarationKind.Property || !isIdentifier((declaration.left as AccessExpression).expression)) {
+                return false;
+            }
+            const name = ((declaration.left as AccessExpression).expression as Identifier).escapedText;
+            const symbol = resolveName(declaration.left, name, SymbolFlags.Value, undefined, undefined, /*isUse*/ true, /*excludeGlobals*/ true);
+            return isThisInitializedDeclaration(symbol?.valueDeclaration);
+        }
+
+        function getContextualTypeForThisPropertyAssignment(binaryExpression: BinaryExpression, kind: AssignmentDeclarationKind): Type | undefined {
+            if (!binaryExpression.symbol) return getTypeOfExpression(binaryExpression.left);
+            if (binaryExpression.symbol.valueDeclaration) {
+                const annotated = getEffectiveTypeAnnotationNode(binaryExpression.symbol.valueDeclaration);
+                if (annotated) {
+                    const type = getTypeFromTypeNode(annotated);
+                    if (type) {
+                        return type;
+                    }
+                }
+            }
+            if (kind === AssignmentDeclarationKind.ModuleExports) return undefined;
+            const thisAccess = cast(binaryExpression.left, isAccessExpression);
+            if (!isObjectLiteralMethod(getThisContainer(thisAccess.expression, /*includeArrowFunctions*/ false))) {
+                return undefined;
+            }
+            const thisType = checkThisExpression(thisAccess.expression);
+            const nameStr = getElementOrPropertyAccessName(thisAccess);
+            return nameStr !== undefined && getTypeOfPropertyOfContextualType(thisType, nameStr) || undefined;
+
+        }
+
         function isCircularMappedProperty(symbol: Symbol) {
             return !!(getCheckFlags(symbol) & CheckFlags.Mapped && !(<MappedSymbol>symbol).type && findResolutionCycleStartIndex(symbol, TypeSystemPropertyName.Type) >= 0);
         }
@@ -25058,7 +25071,8 @@ namespace ts {
         }
 
         function isThisPropertyAccessInConstructor(node: ElementAccessExpression | PropertyAccessExpression | QualifiedName, prop: Symbol) {
-            return isThisProperty(node) && (isAutoTypedProperty(prop) || isConstructorDeclaredProperty(prop)) && getThisContainer(node, /*includeArrowFunctions*/ true) === getDeclaringConstructor(prop);
+            return (isConstructorDeclaredProperty(prop) || isThisProperty(node) && isAutoTypedProperty(prop))
+                && getThisContainer(node, /*includeArrowFunctions*/ true) === getDeclaringConstructor(prop);
         }
 
         function checkPropertyAccessExpressionOrQualifiedName(node: PropertyAccessExpression | QualifiedName, left: Expression | QualifiedName, leftType: Type, right: Identifier | PrivateIdentifier) {

src/compiler/utilities.ts

@@ -1614,6 +1614,10 @@ namespace ts {
             && (<PropertyAccessExpression | ElementAccessExpression>node).expression.kind === SyntaxKind.ThisKeyword;
     }
 
+    export function isThisInitializedDeclaration(node: Node | undefined): boolean {
+        return !!node && isVariableDeclaration(node) && node.initializer?.kind === SyntaxKind.ThisKeyword;
+    }
+
     export function getEntityNameFromTypeNode(node: TypeNode): EntityNameOrEntityNameExpression | undefined {
         switch (node.kind) {
             case SyntaxKind.TypeReference:

tests/baselines/reference/inferringClassMembersFromAssignments6.symbols

@@ -0,0 +1,61 @@
+=== tests/cases/conformance/salsa/inferringClassMembersFromAssignments6.js ===
+function Foonly() {
+>Foonly : Symbol(Foonly, Decl(inferringClassMembersFromAssignments6.js, 0, 0))
+
+    var self = this
+>self : Symbol(self, Decl(inferringClassMembersFromAssignments6.js, 1, 7))
+>this : Symbol(Foonly, Decl(inferringClassMembersFromAssignments6.js, 0, 0))
+
+    self.x = 1
+>self.x : Symbol(Foonly.x, Decl(inferringClassMembersFromAssignments6.js, 1, 19))
+>self : Symbol(Foonly.x, Decl(inferringClassMembersFromAssignments6.js, 1, 19))
+>x : Symbol(Foonly.x, Decl(inferringClassMembersFromAssignments6.js, 1, 19))
+
+    self.m = function() {
+>self.m : Symbol(Foonly.m, Decl(inferringClassMembersFromAssignments6.js, 2, 14))
+>self : Symbol(Foonly.m, Decl(inferringClassMembersFromAssignments6.js, 2, 14))
+>m : Symbol(Foonly.m, Decl(inferringClassMembersFromAssignments6.js, 2, 14))
+
+        console.log(self.x)
+>console.log : Symbol(Console.log, Decl(lib.dom.d.ts, --, --))
+>console : Symbol(console, Decl(lib.dom.d.ts, --, --))
+>log : Symbol(Console.log, Decl(lib.dom.d.ts, --, --))
+>self.x : Symbol(Foonly.x, Decl(inferringClassMembersFromAssignments6.js, 1, 19))
+>self : Symbol(self, Decl(inferringClassMembersFromAssignments6.js, 1, 7))
+>x : Symbol(Foonly.x, Decl(inferringClassMembersFromAssignments6.js, 1, 19))
+    }
+}
+Foonly.prototype.mreal = function() {
+>Foonly.prototype : Symbol(Foonly.mreal, Decl(inferringClassMembersFromAssignments6.js, 6, 1))
+>Foonly : Symbol(Foonly, Decl(inferringClassMembersFromAssignments6.js, 0, 0))
+>prototype : Symbol(Function.prototype, Decl(lib.es5.d.ts, --, --))
+>mreal : Symbol(Foonly.mreal, Decl(inferringClassMembersFromAssignments6.js, 6, 1))
+
+    var self = this
+>self : Symbol(self, Decl(inferringClassMembersFromAssignments6.js, 8, 7))
+>this : Symbol(Foonly, Decl(inferringClassMembersFromAssignments6.js, 0, 0))
+
+    self.y = 2
+>self.y : Symbol(Foonly.y, Decl(inferringClassMembersFromAssignments6.js, 8, 19))
+>self : Symbol(Foonly.y, Decl(inferringClassMembersFromAssignments6.js, 8, 19))
+>y : Symbol(Foonly.y, Decl(inferringClassMembersFromAssignments6.js, 8, 19))
+}
+const foo = new Foonly()
+>foo : Symbol(foo, Decl(inferringClassMembersFromAssignments6.js, 11, 5))
+>Foonly : Symbol(Foonly, Decl(inferringClassMembersFromAssignments6.js, 0, 0))
+
+foo.x
+>foo.x : Symbol(Foonly.x, Decl(inferringClassMembersFromAssignments6.js, 1, 19))
+>foo : Symbol(foo, Decl(inferringClassMembersFromAssignments6.js, 11, 5))
+>x : Symbol(Foonly.x, Decl(inferringClassMembersFromAssignments6.js, 1, 19))
+
+foo.y
+>foo.y : Symbol(Foonly.y, Decl(inferringClassMembersFromAssignments6.js, 8, 19))
+>foo : Symbol(foo, Decl(inferringClassMembersFromAssignments6.js, 11, 5))
+>y : Symbol(Foonly.y, Decl(inferringClassMembersFromAssignments6.js, 8, 19))
+
+foo.m()
+>foo.m : Symbol(Foonly.m, Decl(inferringClassMembersFromAssignments6.js, 2, 14))
+>foo : Symbol(foo, Decl(inferringClassMembersFromAssignments6.js, 11, 5))
+>m : Symbol(Foonly.m, Decl(inferringClassMembersFromAssignments6.js, 2, 14))
+

tests/baselines/reference/inferringClassMembersFromAssignments6.types

@@ -0,0 +1,73 @@
+=== tests/cases/conformance/salsa/inferringClassMembersFromAssignments6.js ===
+function Foonly() {
+>Foonly : typeof Foonly
+
+    var self = this
+>self : this
+>this : this
+
+    self.x = 1
+>self.x = 1 : 1
+>self.x : any
+>self : this
+>x : any
+>1 : 1
+
+    self.m = function() {
+>self.m = function() {        console.log(self.x)    } : () => void
+>self.m : any
+>self : this
+>m : any
+>function() {        console.log(self.x)    } : () => void
+
+        console.log(self.x)
+>console.log(self.x) : void
+>console.log : (...data: any[]) => void
+>console : Console
+>log : (...data: any[]) => void
+>self.x : number
+>self : this
+>x : number
+    }
+}
+Foonly.prototype.mreal = function() {
+>Foonly.prototype.mreal = function() {    var self = this    self.y = 2} : () => void
+>Foonly.prototype.mreal : any
+>Foonly.prototype : any
+>Foonly : typeof Foonly
+>prototype : any
+>mreal : any
+>function() {    var self = this    self.y = 2} : () => void
+
+    var self = this
+>self : this
+>this : this
+
+    self.y = 2
+>self.y = 2 : 2
+>self.y : number | undefined
+>self : this
+>y : number | undefined
+>2 : 2
+}
+const foo = new Foonly()
+>foo : Foonly
+>new Foonly() : Foonly
+>Foonly : typeof Foonly
+
+foo.x
+>foo.x : number
+>foo : Foonly
+>x : number
+
+foo.y
+>foo.y : number | undefined
+>foo : Foonly
+>y : number | undefined
+
+foo.m()
+>foo.m() : void
+>foo.m : () => void
+>foo : Foonly
+>m : () => void
+