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diff --git a/‎src/compiler/binder.ts
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+58-9Lines changed: 58 additions & 9 deletions b/‎src/compiler/binder.ts
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+58-9Lines changed: 58 additions & 9 deletions
diff --git a/‎src/compiler/checker.ts
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+96-6Lines changed: 96 additions & 6 deletions b/‎src/compiler/checker.ts
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+96-6Lines changed: 96 additions & 6 deletions
diff --git a/‎src/compiler/types.ts
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+13-1Lines changed: 13 additions & 1 deletion b/‎src/compiler/types.ts
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+13-1Lines changed: 13 additions & 1 deletion
@@ -2112,7 +2112,7 @@ namespace ts {
                             // Nothing to do
                             break;
                         default:
-                            Debug.fail("Unknown special property assignment kind");
+                            Debug.fail("Unknown binary expression special property assignment kind");
                     }
                     return checkStrictModeBinaryExpression(<BinaryExpression>node);
                 case SyntaxKind.CatchClause:
@@ -2188,6 +2188,19 @@ namespace ts {
                     return bindFunctionExpression(<FunctionExpression>node);
 
                 case SyntaxKind.CallExpression:
+                    const assignmentKind = getAssignmentDeclarationKind(node as CallExpression);
+                    switch (assignmentKind) {
+                        case AssignmentDeclarationKind.ObjectDefinePropertyValue:
+                            return bindObjectDefinePropertyAssignment(node as BindableObjectDefinePropertyCall);
+                        case AssignmentDeclarationKind.ObjectDefinePropertyExports:
+                            return bindObjectDefinePropertyExport(node as BindableObjectDefinePropertyCall);
+                        case AssignmentDeclarationKind.ObjectDefinePrototypeProperty:
+                            return bindObjectDefinePrototypeProperty(node as BindableObjectDefinePropertyCall);
+                        case AssignmentDeclarationKind.None:
+                            break; // Nothing to do
+                        default:
+                            return Debug.fail("Unknown call expression assignment declaration kind");
+                    }
                     if (isInJSFile(node)) {
                         bindCallExpression(<CallExpression>node);
                     }
@@ -2351,6 +2364,22 @@ namespace ts {
             return true;
         }
 
+        function bindObjectDefinePropertyExport(node: BindableObjectDefinePropertyCall) {
+            if (!setCommonJsModuleIndicator(node)) {
+                return;
+            }
+            const symbol = forEachIdentifierInEntityName(node.arguments[0], /*parent*/ undefined, (id, symbol) => {
+                if (symbol) {
+                    addDeclarationToSymbol(symbol, id, SymbolFlags.Module | SymbolFlags.Assignment);
+                }
+                return symbol;
+            });
+            if (symbol) {
+                const flags = SymbolFlags.Property | SymbolFlags.ExportValue;
+                declareSymbol(symbol.exports!, symbol, node, flags, SymbolFlags.None);
+            }
+        }
+
         function bindExportsPropertyAssignment(node: BinaryExpression) {
             // When we create a property via 'exports.foo = bar', the 'exports.foo' property access
             // expression is the declaration
@@ -2458,6 +2487,11 @@ namespace ts {
             bindPropertyAssignment(lhs.expression, lhs, /*isPrototypeProperty*/ false);
         }
 
+        function bindObjectDefinePrototypeProperty(node: BindableObjectDefinePropertyCall) {
+            const namespaceSymbol = lookupSymbolForPropertyAccess((node.arguments[0] as PropertyAccessExpression).expression as EntityNameExpression);
+            bindPotentiallyNewExpandoMemberToNamespace(node, namespaceSymbol, /*isPrototypeProperty*/ true);
+        }
+
         /**
          * For `x.prototype.y = z`, declare a member `y` on `x` if `x` is a function or class, or not declared.
          * Note that jsdoc preceding an ExpressionStatement like `x.prototype.y;` is also treated as a declaration.
@@ -2476,6 +2510,12 @@ namespace ts {
             bindPropertyAssignment(constructorFunction, lhs, /*isPrototypeProperty*/ true);
         }
 
+        function bindObjectDefinePropertyAssignment(node: BindableObjectDefinePropertyCall) {
+            let namespaceSymbol = lookupSymbolForPropertyAccess(node.arguments[0]);
+            const isToplevel = node.parent.parent.kind === SyntaxKind.SourceFile;
+            namespaceSymbol = bindPotentiallyMissingNamespaces(namespaceSymbol, node.arguments[0], isToplevel, /*isPrototypeProperty*/ false);
+            bindPotentiallyNewExpandoMemberToNamespace(node, namespaceSymbol, /*isPrototypeProperty*/ false);
+        }
 
         function bindSpecialPropertyAssignment(node: BinaryExpression) {
             const lhs = node.left as PropertyAccessEntityNameExpression;
@@ -2507,16 +2547,12 @@ namespace ts {
             bindPropertyAssignment(node.expression, node, /*isPrototypeProperty*/ false);
         }
 
-        function bindPropertyAssignment(name: EntityNameExpression, propertyAccess: PropertyAccessEntityNameExpression, isPrototypeProperty: boolean) {
-            let namespaceSymbol = lookupSymbolForPropertyAccess(name);
-            const isToplevel = isBinaryExpression(propertyAccess.parent)
-                ? getParentOfBinaryExpression(propertyAccess.parent).parent.kind === SyntaxKind.SourceFile
-                : propertyAccess.parent.parent.kind === SyntaxKind.SourceFile;
+        function bindPotentiallyMissingNamespaces(namespaceSymbol: Symbol | undefined, entityName: EntityNameExpression, isToplevel: boolean, isPrototypeProperty: boolean) {
             if (isToplevel && !isPrototypeProperty && (!namespaceSymbol || !(namespaceSymbol.flags & SymbolFlags.Namespace))) {
                 // make symbols or add declarations for intermediate containers
                 const flags = SymbolFlags.Module | SymbolFlags.Assignment;
                 const excludeFlags = SymbolFlags.ValueModuleExcludes & ~SymbolFlags.Assignment;
-                namespaceSymbol = forEachIdentifierInEntityName(propertyAccess.expression, namespaceSymbol, (id, symbol, parent) => {
+                namespaceSymbol = forEachIdentifierInEntityName(entityName, namespaceSymbol, (id, symbol, parent) => {
                     if (symbol) {
                         addDeclarationToSymbol(symbol, id, flags);
                         return symbol;
@@ -2528,6 +2564,10 @@ namespace ts {
                     }
                 });
             }
+            return namespaceSymbol;
+        }
+
+        function bindPotentiallyNewExpandoMemberToNamespace(declaration: PropertyAccessEntityNameExpression | CallExpression, namespaceSymbol: Symbol | undefined, isPrototypeProperty: boolean) {
             if (!namespaceSymbol || !isExpandoSymbol(namespaceSymbol)) {
                 return;
             }
@@ -2537,10 +2577,19 @@ namespace ts {
                 (namespaceSymbol.members || (namespaceSymbol.members = createSymbolTable())) :
                 (namespaceSymbol.exports || (namespaceSymbol.exports = createSymbolTable()));
 
-            const isMethod = isFunctionLikeDeclaration(getAssignedExpandoInitializer(propertyAccess)!);
+            const isMethod = isFunctionLikeDeclaration(getAssignedExpandoInitializer(declaration)!);
             const includes = isMethod ? SymbolFlags.Method : SymbolFlags.Property;
             const excludes = isMethod ? SymbolFlags.MethodExcludes : SymbolFlags.PropertyExcludes;
-            declareSymbol(symbolTable, namespaceSymbol, propertyAccess, includes | SymbolFlags.Assignment, excludes & ~SymbolFlags.Assignment);
+            declareSymbol(symbolTable, namespaceSymbol, declaration, includes | SymbolFlags.Assignment, excludes & ~SymbolFlags.Assignment);
+        }
+
+        function bindPropertyAssignment(name: EntityNameExpression, propertyAccess: PropertyAccessEntityNameExpression, isPrototypeProperty: boolean) {
+            let namespaceSymbol = lookupSymbolForPropertyAccess(name);
+            const isToplevel = isBinaryExpression(propertyAccess.parent)
+                ? getParentOfBinaryExpression(propertyAccess.parent).parent.kind === SyntaxKind.SourceFile
+                : propertyAccess.parent.parent.kind === SyntaxKind.SourceFile;
+            namespaceSymbol = bindPotentiallyMissingNamespaces(namespaceSymbol, propertyAccess.expression, isToplevel, isPrototypeProperty);
+            bindPotentiallyNewExpandoMemberToNamespace(propertyAccess, namespaceSymbol, isPrototypeProperty);
         }
 
         /**
 
@@ -4881,7 +4881,7 @@ namespace ts {
             let jsdocType: Type | undefined;
             let types: Type[] | undefined;
             for (const declaration of symbol.declarations) {
-                const expression = isBinaryExpression(declaration) ? declaration :
+                const expression = (isBinaryExpression(declaration) || isCallExpression(declaration)) ? declaration :
                     isPropertyAccessExpression(declaration) ? isBinaryExpression(declaration.parent) ? declaration.parent : declaration :
                         undefined;
                 if (!expression) {
@@ -4897,9 +4897,11 @@ namespace ts {
                         definedInMethod = true;
                     }
                 }
-                jsdocType = getJSDocTypeFromAssignmentDeclaration(jsdocType, expression, symbol, declaration);
+                if (!isCallExpression(expression)) {
+                    jsdocType = getJSDocTypeFromAssignmentDeclaration(jsdocType, expression, symbol, declaration);
+                }
                 if (!jsdocType) {
-                    (types || (types = [])).push(isBinaryExpression(expression) ? getInitializerTypeFromAssignmentDeclaration(symbol, resolvedSymbol, expression, kind) : neverType);
+                    (types || (types = [])).push((isBinaryExpression(expression) || isCallExpression(expression)) ? getInitializerTypeFromAssignmentDeclaration(symbol, resolvedSymbol, expression, kind) : neverType);
                 }
             }
             let type = jsdocType;
@@ -4960,7 +4962,32 @@ namespace ts {
         }
 
         /** If we don't have an explicit JSDoc type, get the type from the initializer. */
-        function getInitializerTypeFromAssignmentDeclaration(symbol: Symbol, resolvedSymbol: Symbol | undefined, expression: BinaryExpression, kind: AssignmentDeclarationKind) {
+        function getInitializerTypeFromAssignmentDeclaration(symbol: Symbol, resolvedSymbol: Symbol | undefined, expression: BinaryExpression | CallExpression, kind: AssignmentDeclarationKind) {
+            if (isCallExpression(expression)) {
+                if (resolvedSymbol) {
+                    return getTypeOfSymbol(resolvedSymbol); // This shouldn't happen except under some hopefully forbidden merges of export assignments and object define assignments
+                }
+                const objectLitType = checkExpressionCached((expression as BindableObjectDefinePropertyCall).arguments[2]);
+                const valueType = getTypeOfPropertyOfType(objectLitType, "value" as __String);
+                if (valueType) {
+                    return valueType;
+                }
+                const getFunc = getTypeOfPropertyOfType(objectLitType, "get" as __String);
+                if (getFunc) {
+                    const getSig = getSingleCallSignature(getFunc);
+                    if (getSig) {
+                        return getReturnTypeOfSignature(getSig);
+                    }
+                }
+                const setFunc = getTypeOfPropertyOfType(objectLitType, "set" as __String);
+                if (setFunc) {
+                    const setSig = getSingleCallSignature(setFunc);
+                    if (setSig) {
+                        return getTypeOfFirstParameterOfSignature(setSig);
+                    }
+                }
+                return anyType;
+            }
             const type = resolvedSymbol ? getTypeOfSymbol(resolvedSymbol) : getWidenedLiteralType(checkExpressionCached(expression.right));
             if (type.flags & TypeFlags.Object &&
                 kind === AssignmentDeclarationKind.ModuleExports &&
@@ -5212,7 +5239,7 @@ namespace ts {
             }
             let type: Type | undefined;
             if (isInJSFile(declaration) &&
-                (isBinaryExpression(declaration) || isPropertyAccessExpression(declaration) && isBinaryExpression(declaration.parent))) {
+                (isCallExpression(declaration) || isBinaryExpression(declaration) || isPropertyAccessExpression(declaration) && isBinaryExpression(declaration.parent))) {
                 type = getWidenedTypeFromAssignmentDeclaration(symbol);
             }
             else if (isJSDocPropertyLikeTag(declaration)
@@ -16179,6 +16206,31 @@ namespace ts {
                 getAssignmentDeclarationKind(container.parent.parent.parent) === AssignmentDeclarationKind.Prototype) {
                 return (container.parent.parent.parent.left as PropertyAccessExpression).expression;
             }
+            // Object.defineProperty(x, "method", { value: function() { } });
+            // Object.defineProperty(x, "method", { set: (x: () => void) => void });
+            // Object.defineProperty(x, "method", { get: () => function() { }) });
+            else if (container.kind === SyntaxKind.FunctionExpression &&
+                isPropertyAssignment(container.parent) &&
+                isIdentifier(container.parent.name) &&
+                (container.parent.name.escapedText === "value" || container.parent.name.escapedText === "get" || container.parent.name.escapedText === "set") &&
+                isObjectLiteralExpression(container.parent.parent) &&
+                isCallExpression(container.parent.parent.parent) &&
+                container.parent.parent.parent.arguments[2] === container.parent.parent &&
+                getAssignmentDeclarationKind(container.parent.parent.parent) === AssignmentDeclarationKind.ObjectDefinePrototypeProperty) {
+                return (container.parent.parent.parent.arguments[0] as PropertyAccessExpression).expression;
+            }
+            // Object.defineProperty(x, "method", { value() { } });
+            // Object.defineProperty(x, "method", { set(x: () => void) {} });
+            // Object.defineProperty(x, "method", { get() { return () => {} } });
+            else if (isMethodDeclaration(container) &&
+                isIdentifier(container.name) &&
+                (container.name.escapedText === "value" || container.name.escapedText === "get" || container.name.escapedText === "set") &&
+                isObjectLiteralExpression(container.parent) &&
+                isCallExpression(container.parent.parent) &&
+                container.parent.parent.arguments[2] === container.parent &&
+                getAssignmentDeclarationKind(container.parent.parent) === AssignmentDeclarationKind.ObjectDefinePrototypeProperty) {
+                return (container.parent.parent.arguments[0] as PropertyAccessExpression).expression;
+            }
         }
 
         function getTypeForThisExpressionFromJSDoc(node: Node) {
@@ -16741,6 +16793,10 @@ namespace ts {
                     }
                     const thisType = checkThisExpression(thisAccess.expression);
                     return thisType && getTypeOfPropertyOfContextualType(thisType, thisAccess.name.escapedText) || false;
+                case AssignmentDeclarationKind.ObjectDefinePropertyValue:
+                case AssignmentDeclarationKind.ObjectDefinePropertyExports:
+                case AssignmentDeclarationKind.ObjectDefinePrototypeProperty:
+                    return Debug.fail("Does not apply");
                 default:
                     return Debug.assertNever(kind);
             }
@@ -21132,18 +21188,52 @@ namespace ts {
             return true;
         }
 
+        function isReadonlyAssignmentDeclaration(d: Declaration) {
+            if (!isCallExpression(d)) {
+                return false;
+            }
+            if (!isBindableObjectDefinePropertyCall(d)) {
+                return false;
+            }
+            const objectLitType = checkExpressionCached(d.arguments[2]);
+            const valueType = getTypeOfPropertyOfType(objectLitType, "value" as __String);
+            if (valueType) {
+                const writableProp = getPropertyOfType(objectLitType, "writable" as __String);
+                const writableType = writableProp && getTypeOfSymbol(writableProp);
+                if (!writableType || writableType === falseType || writableType === regularFalseType) {
+                    return true;
+                }
+                // We include this definition whereupon we walk back and check the type at the declaration because
+                // The usual definition of `Object.defineProperty` will _not_ cause literal types to be preserved in the
+                // argument types, should the type be contextualized by the call itself.
+                if (writableProp && writableProp.valueDeclaration && isPropertyAssignment(writableProp.valueDeclaration)) {
+                    const initializer = writableProp.valueDeclaration.initializer;
+                    const rawOriginalType = checkExpression(initializer);
+                    if (rawOriginalType === falseType || rawOriginalType === regularFalseType) {
+                        return true;
+                    }
+                }
+                return false;
+            }
+            const setProp = getPropertyOfType(objectLitType, "set" as __String);
+            return !setProp;
+        }
+
         function isReadonlySymbol(symbol: Symbol): boolean {
             // The following symbols are considered read-only:
             // Properties with a 'readonly' modifier
             // Variables declared with 'const'
             // Get accessors without matching set accessors
             // Enum members
+            // Object.defineProperty assignments with writable false or no setter
             // Unions and intersections of the above (unions and intersections eagerly set isReadonly on creation)
             return !!(getCheckFlags(symbol) & CheckFlags.Readonly ||
                 symbol.flags & SymbolFlags.Property && getDeclarationModifierFlagsFromSymbol(symbol) & ModifierFlags.Readonly ||
                 symbol.flags & SymbolFlags.Variable && getDeclarationNodeFlagsFromSymbol(symbol) & NodeFlags.Const ||
                 symbol.flags & SymbolFlags.Accessor && !(symbol.flags & SymbolFlags.SetAccessor) ||
-                symbol.flags & SymbolFlags.EnumMember);
+                symbol.flags & SymbolFlags.EnumMember ||
+                some(symbol.declarations, isReadonlyAssignmentDeclaration)
+            );
         }
 
         function isReferenceToReadonlyEntity(expr: Expression, symbol: Symbol): boolean {
 
@@ -790,7 +790,7 @@ namespace ts {
 
     export type PropertyName = Identifier | StringLiteral | NumericLiteral | ComputedPropertyName;
 
-    export type DeclarationName = Identifier | StringLiteral | NumericLiteral | ComputedPropertyName | BindingPattern;
+    export type DeclarationName = Identifier | StringLiteralLike | NumericLiteral | ComputedPropertyName | BindingPattern;
 
     export interface Declaration extends Node {
         _declarationBrand: any;
@@ -1774,6 +1774,9 @@ namespace ts {
         arguments: NodeArray<Expression>;
     }
 
+    /** @internal */
+    export type BindableObjectDefinePropertyCall = CallExpression & { arguments: { 0: EntityNameExpression, 1: StringLiteralLike | NumericLiteral, 2: ObjectLiteralExpression } };
+
     // see: https://tc39.github.io/ecma262/#prod-SuperCall
     export interface SuperCall extends CallExpression {
         expression: SuperExpression;
@@ -4347,6 +4350,15 @@ namespace ts {
         Property,
         // F.prototype = { ... }
         Prototype,
+        // Object.defineProperty(x, 'name', { value: any, writable?: boolean (false by default) });
+        // Object.defineProperty(x, 'name', { get: Function, set: Function });
+        // Object.defineProperty(x, 'name', { get: Function });
+        // Object.defineProperty(x, 'name', { set: Function });
+        ObjectDefinePropertyValue,
+        // Object.defineProperty(exports || module.exports, 'name', ...);
+        ObjectDefinePropertyExports,
+        // Object.defineProperty(Foo.prototype, 'name', ...);
+        ObjectDefinePrototypeProperty,
     }
 
     /** @deprecated Use FileExtensionInfo instead. */