Fixes #17080

src/compiler/checker.ts

@@ -13048,7 +13048,7 @@ namespace ts {
                 node.parent.kind === SyntaxKind.NonNullExpression ||
                 declaration.kind === SyntaxKind.VariableDeclaration && (<VariableDeclaration>declaration).exclamationToken ||
                 declaration.flags & NodeFlags.Ambient;
-            const initialType = assumeInitialized ? (isParameter ? removeOptionalityFromDeclaredType(type, getRootDeclaration(declaration) as VariableLikeDeclaration) : type) :
+            const initialType = assumeInitialized ? (isParameter ? removeOptionalityFromDeclaredType(type, declaration as VariableLikeDeclaration) : type) :
                 type === autoType || type === autoArrayType ? undefinedType :
                     getOptionalType(type);
             const flowType = getFlowTypeOfReference(node, type, initialType, flowContainer, !assumeInitialized);

tests/baselines/reference/optionalParameterInDestructuringWithInitializer.errors.txt

@@ -0,0 +1,92 @@
+tests/cases/compiler/optionalParameterInDestructuringWithInitializer.ts(6,8): error TS2345: Argument of type 'number | undefined' is not assignable to parameter of type 'number'.
+  Type 'undefined' is not assignable to type 'number'.
+tests/cases/compiler/optionalParameterInDestructuringWithInitializer.ts(16,7): error TS2345: Argument of type 'number | undefined' is not assignable to parameter of type 'number'.
+  Type 'undefined' is not assignable to type 'number'.
+tests/cases/compiler/optionalParameterInDestructuringWithInitializer.ts(21,7): error TS2345: Argument of type 'number | undefined' is not assignable to parameter of type 'number'.
+  Type 'undefined' is not assignable to type 'number'.
+tests/cases/compiler/optionalParameterInDestructuringWithInitializer.ts(31,8): error TS2345: Argument of type 'number | undefined' is not assignable to parameter of type 'number'.
+  Type 'undefined' is not assignable to type 'number'.
+tests/cases/compiler/optionalParameterInDestructuringWithInitializer.ts(45,10): error TS2345: Argument of type 'number | undefined' is not assignable to parameter of type 'number'.
+  Type 'undefined' is not assignable to type 'number'.
+tests/cases/compiler/optionalParameterInDestructuringWithInitializer.ts(53,11): error TS2345: Argument of type 'number | null' is not assignable to parameter of type 'number | undefined'.
+  Type 'null' is not assignable to type 'number | undefined'.
+
+
+==== tests/cases/compiler/optionalParameterInDestructuringWithInitializer.ts (6 errors) ====
+    // https://github.com/Microsoft/TypeScript/issues/17080
+
+    declare function f(a:number,b:number): void;
+
+    function func1( {a, b}: {a: number, b?: number} = {a: 1, b: 2} ) {
+      f(a, b)
+           ~
+!!! error TS2345: Argument of type 'number | undefined' is not assignable to parameter of type 'number'.
+!!! error TS2345:   Type 'undefined' is not assignable to type 'number'.
+      // error
+    }
+
+    function func2( {a, b = 3}: {a: number, b?:number} = {a: 1,b: 2} ) {
+      f(a, b)
+      // no error
+    }
+
+    function func3( {a, b}: {a: number, b?: number} = {a: 1} ) {
+      f(a,b)
+          ~
+!!! error TS2345: Argument of type 'number | undefined' is not assignable to parameter of type 'number'.
+!!! error TS2345:   Type 'undefined' is not assignable to type 'number'.
+      // error
+    }
+
+    function func4( {a: {b, c}, d}: {a: {b: number,c?: number},d: number} = {a: {b: 1,c: 2},d: 3} ) {
+      f(b,c)
+          ~
+!!! error TS2345: Argument of type 'number | undefined' is not assignable to parameter of type 'number'.
+!!! error TS2345:   Type 'undefined' is not assignable to type 'number'.
+      // error
+    }
+
+    function func5({a: {b, c = 4}, d}: {a: {b: number,c?: number},d: number} = {a: {b: 1,c: 2},d: 3} ) {
+      f(b, c)
+      // no error
+    }
+
+    function func6( {a: {b, c} = {b: 4, c: 5}, d}: {a: {b: number, c?: number}, d: number} = {a: {b: 1,c: 2}, d: 3} ) {
+      f(b, c)
+           ~
+!!! error TS2345: Argument of type 'number | undefined' is not assignable to parameter of type 'number'.
+!!! error TS2345:   Type 'undefined' is not assignable to type 'number'.
+      // error
+    }
+
+    function func7( {a: {b, c = 6} = {b: 4, c: 5}, d}: {a: {b: number, c?: number}, d: number} = {a: {b: 1, c: 2}, d: 3} ) {
+      f(b, c)
+      // no error
+    }
+
+    interface Foo {
+      readonly bar?: number;
+    }
+
+    function performFoo({ bar }: Foo = {}) {
+      useBar(bar);
+             ~~~
+!!! error TS2345: Argument of type 'number | undefined' is not assignable to parameter of type 'number'.
+!!! error TS2345:   Type 'undefined' is not assignable to type 'number'.
+    }
+
+    declare function useBar(bar: number): void;
+
+    performFoo();
+
+    function performFoo2({ bar = null }: Foo = {}) {
+      useBar2(bar);
+              ~~~
+!!! error TS2345: Argument of type 'number | null' is not assignable to parameter of type 'number | undefined'.
+!!! error TS2345:   Type 'null' is not assignable to type 'number | undefined'.
+    }
+
+    declare function useBar2(bar: number | undefined): void;
+
+    performFoo2();
+

tests/baselines/reference/optionalParameterInDestructuringWithInitializer.js

@@ -0,0 +1,108 @@
+//// [optionalParameterInDestructuringWithInitializer.ts]
+// https://github.com/Microsoft/TypeScript/issues/17080
+
+declare function f(a:number,b:number): void;
+
+function func1( {a, b}: {a: number, b?: number} = {a: 1, b: 2} ) {
+  f(a, b)
+  // error
+}
+
+function func2( {a, b = 3}: {a: number, b?:number} = {a: 1,b: 2} ) {
+  f(a, b)
+  // no error
+}
+
+function func3( {a, b}: {a: number, b?: number} = {a: 1} ) {
+  f(a,b)
+  // error
+}
+
+function func4( {a: {b, c}, d}: {a: {b: number,c?: number},d: number} = {a: {b: 1,c: 2},d: 3} ) {
+  f(b,c)
+  // error
+}
+
+function func5({a: {b, c = 4}, d}: {a: {b: number,c?: number},d: number} = {a: {b: 1,c: 2},d: 3} ) {
+  f(b, c)
+  // no error
+}
+
+function func6( {a: {b, c} = {b: 4, c: 5}, d}: {a: {b: number, c?: number}, d: number} = {a: {b: 1,c: 2}, d: 3} ) {
+  f(b, c)
+  // error
+}
+
+function func7( {a: {b, c = 6} = {b: 4, c: 5}, d}: {a: {b: number, c?: number}, d: number} = {a: {b: 1, c: 2}, d: 3} ) {
+  f(b, c)
+  // no error
+}
+
+interface Foo {
+  readonly bar?: number;
+}
+
+function performFoo({ bar }: Foo = {}) {
+  useBar(bar);
+}
+
+declare function useBar(bar: number): void;
+
+performFoo();
+
+function performFoo2({ bar = null }: Foo = {}) {
+  useBar2(bar);
+}
+
+declare function useBar2(bar: number | undefined): void;
+
+performFoo2();
+
+
+//// [optionalParameterInDestructuringWithInitializer.js]
+// https://github.com/Microsoft/TypeScript/issues/17080
+function func1(_a) {
+    var _b = _a === void 0 ? { a: 1, b: 2 } : _a, a = _b.a, b = _b.b;
+    f(a, b);
+    // error
+}
+function func2(_a) {
+    var _b = _a === void 0 ? { a: 1, b: 2 } : _a, a = _b.a, _c = _b.b, b = _c === void 0 ? 3 : _c;
+    f(a, b);
+    // no error
+}
+function func3(_a) {
+    var _b = _a === void 0 ? { a: 1 } : _a, a = _b.a, b = _b.b;
+    f(a, b);
+    // error
+}
+function func4(_a) {
+    var _b = _a === void 0 ? { a: { b: 1, c: 2 }, d: 3 } : _a, _c = _b.a, b = _c.b, c = _c.c, d = _b.d;
+    f(b, c);
+    // error
+}
+function func5(_a) {
+    var _b = _a === void 0 ? { a: { b: 1, c: 2 }, d: 3 } : _a, _c = _b.a, b = _c.b, _d = _c.c, c = _d === void 0 ? 4 : _d, d = _b.d;
+    f(b, c);
+    // no error
+}
+function func6(_a) {
+    var _b = _a === void 0 ? { a: { b: 1, c: 2 }, d: 3 } : _a, _c = _b.a, _d = _c === void 0 ? { b: 4, c: 5 } : _c, b = _d.b, c = _d.c, d = _b.d;
+    f(b, c);
+    // error
+}
+function func7(_a) {
+    var _b = _a === void 0 ? { a: { b: 1, c: 2 }, d: 3 } : _a, _c = _b.a, _d = _c === void 0 ? { b: 4, c: 5 } : _c, b = _d.b, _e = _d.c, c = _e === void 0 ? 6 : _e, d = _b.d;
+    f(b, c);
+    // no error
+}
+function performFoo(_a) {
+    var bar = (_a === void 0 ? {} : _a).bar;
+    useBar(bar);
+}
+performFoo();
+function performFoo2(_a) {
+    var _b = (_a === void 0 ? {} : _a).bar, bar = _b === void 0 ? null : _b;
+    useBar2(bar);
+}
+performFoo2();