Remove undefined from source type of renaming destructuring assignment with default (#41042)

* Remove undefined from source type of destructuring assignment with renaming

* add a test

* add test case from original issue

* add test with undefined default value

* add more test cases with const declaration

src/compiler/checker.ts

@@ -33704,6 +33704,10 @@ namespace ts {
             if (target.kind === SyntaxKind.BinaryExpression && (target as BinaryExpression).operatorToken.kind === SyntaxKind.EqualsToken) {
                 checkBinaryExpression(target as BinaryExpression, checkMode);
                 target = (target as BinaryExpression).left;
+                // A default value is specified, so remove undefined from the final type.
+                if (strictNullChecks) {
+                    sourceType = getTypeWithFacts(sourceType, TypeFacts.NEUndefined);
+                }
             }
             if (target.kind === SyntaxKind.ObjectLiteralExpression) {
                 return checkObjectLiteralAssignment(target as ObjectLiteralExpression, sourceType, rightIsThis);

tests/baselines/reference/destructuringAssignmentWithDefault2.errors.txt

@@ -0,0 +1,42 @@
+tests/cases/compiler/destructuringAssignmentWithDefault2.ts(11,4): error TS2322: Type 'undefined' is not assignable to type 'number'.
+tests/cases/compiler/destructuringAssignmentWithDefault2.ts(11,4): error TS2322: Type 'number | undefined' is not assignable to type 'number'.
+  Type 'undefined' is not assignable to type 'number'.
+tests/cases/compiler/destructuringAssignmentWithDefault2.ts(12,7): error TS2322: Type 'undefined' is not assignable to type 'number'.
+tests/cases/compiler/destructuringAssignmentWithDefault2.ts(13,7): error TS2322: Type 'undefined' is not assignable to type 'number'.
+
+
+==== tests/cases/compiler/destructuringAssignmentWithDefault2.ts (4 errors) ====
+    const a: { x?: number; y?: number } = { };
+    
+    let x: number;
+    
+    // Should not error out
+    ({ x = 0 } = a);
+    ({ x: x = 0} = a);
+    ({ y: x = 0} = a);
+    
+    // Should be error
+    ({ x = undefined } = a);
+       ~
+!!! error TS2322: Type 'undefined' is not assignable to type 'number'.
+       ~
+!!! error TS2322: Type 'number | undefined' is not assignable to type 'number'.
+!!! error TS2322:   Type 'undefined' is not assignable to type 'number'.
+    ({ x: x = undefined } = a);
+          ~
+!!! error TS2322: Type 'undefined' is not assignable to type 'number'.
+    ({ y: x = undefined } = a);
+          ~
+!!! error TS2322: Type 'undefined' is not assignable to type 'number'.
+    
+    const { x: z1 } = a;
+    const { x: z2 = 0 } = a;
+    const { x: z3 = undefined } = a;
+    
+    
+    declare const r: Iterator<number>;
+    let done: boolean;
+    let value;
+    
+    ({ done = false, value } = r.next());
+    ({ done: done = false, value } = r.next());

tests/baselines/reference/destructuringAssignmentWithDefault2.js

@@ -0,0 +1,46 @@
+//// [destructuringAssignmentWithDefault2.ts]
+const a: { x?: number; y?: number } = { };
+
+let x: number;
+
+// Should not error out
+({ x = 0 } = a);
+({ x: x = 0} = a);
+({ y: x = 0} = a);
+
+// Should be error
+({ x = undefined } = a);
+({ x: x = undefined } = a);
+({ y: x = undefined } = a);
+
+const { x: z1 } = a;
+const { x: z2 = 0 } = a;
+const { x: z3 = undefined } = a;
+
+
+declare const r: Iterator<number>;
+let done: boolean;
+let value;
+
+({ done = false, value } = r.next());
+({ done: done = false, value } = r.next());
+
+//// [destructuringAssignmentWithDefault2.js]
+var _a, _b, _c, _d, _e, _f, _g, _h, _j, _k;
+var a = {};
+var x;
+// Should not error out
+(_a = a.x, x = _a === void 0 ? 0 : _a);
+(_b = a.x, x = _b === void 0 ? 0 : _b);
+(_c = a.y, x = _c === void 0 ? 0 : _c);
+// Should be error
+(_d = a.x, x = _d === void 0 ? undefined : _d);
+(_e = a.x, x = _e === void 0 ? undefined : _e);
+(_f = a.y, x = _f === void 0 ? undefined : _f);
+var z1 = a.x;
+var _l = a.x, z2 = _l === void 0 ? 0 : _l;
+var _m = a.x, z3 = _m === void 0 ? undefined : _m;
+var done;
+var value;
+(_g = r.next(), _h = _g.done, done = _h === void 0 ? false : _h, value = _g.value);
+(_j = r.next(), _k = _j.done, done = _k === void 0 ? false : _k, value = _j.value);

tests/baselines/reference/destructuringAssignmentWithDefault2.symbols

@@ -0,0 +1,84 @@
+=== tests/cases/compiler/destructuringAssignmentWithDefault2.ts ===
+const a: { x?: number; y?: number } = { };
+>a : Symbol(a, Decl(destructuringAssignmentWithDefault2.ts, 0, 5))
+>x : Symbol(x, Decl(destructuringAssignmentWithDefault2.ts, 0, 10))
+>y : Symbol(y, Decl(destructuringAssignmentWithDefault2.ts, 0, 22))
+
+let x: number;
+>x : Symbol(x, Decl(destructuringAssignmentWithDefault2.ts, 2, 3))
+
+// Should not error out
+({ x = 0 } = a);
+>x : Symbol(x, Decl(destructuringAssignmentWithDefault2.ts, 5, 2))
+>a : Symbol(a, Decl(destructuringAssignmentWithDefault2.ts, 0, 5))
+
+({ x: x = 0} = a);
+>x : Symbol(x, Decl(destructuringAssignmentWithDefault2.ts, 6, 2))
+>x : Symbol(x, Decl(destructuringAssignmentWithDefault2.ts, 2, 3))
+>a : Symbol(a, Decl(destructuringAssignmentWithDefault2.ts, 0, 5))
+
+({ y: x = 0} = a);
+>y : Symbol(y, Decl(destructuringAssignmentWithDefault2.ts, 7, 2))
+>x : Symbol(x, Decl(destructuringAssignmentWithDefault2.ts, 2, 3))
+>a : Symbol(a, Decl(destructuringAssignmentWithDefault2.ts, 0, 5))
+
+// Should be error
+({ x = undefined } = a);
+>x : Symbol(x, Decl(destructuringAssignmentWithDefault2.ts, 10, 2))
+>undefined : Symbol(undefined)
+>a : Symbol(a, Decl(destructuringAssignmentWithDefault2.ts, 0, 5))
+
+({ x: x = undefined } = a);
+>x : Symbol(x, Decl(destructuringAssignmentWithDefault2.ts, 11, 2))
+>x : Symbol(x, Decl(destructuringAssignmentWithDefault2.ts, 2, 3))
+>undefined : Symbol(undefined)
+>a : Symbol(a, Decl(destructuringAssignmentWithDefault2.ts, 0, 5))
+
+({ y: x = undefined } = a);
+>y : Symbol(y, Decl(destructuringAssignmentWithDefault2.ts, 12, 2))
+>x : Symbol(x, Decl(destructuringAssignmentWithDefault2.ts, 2, 3))
+>undefined : Symbol(undefined)
+>a : Symbol(a, Decl(destructuringAssignmentWithDefault2.ts, 0, 5))
+
+const { x: z1 } = a;
+>x : Symbol(x, Decl(destructuringAssignmentWithDefault2.ts, 0, 10))
+>z1 : Symbol(z1, Decl(destructuringAssignmentWithDefault2.ts, 14, 7))
+>a : Symbol(a, Decl(destructuringAssignmentWithDefault2.ts, 0, 5))
+
+const { x: z2 = 0 } = a;
+>x : Symbol(x, Decl(destructuringAssignmentWithDefault2.ts, 0, 10))
+>z2 : Symbol(z2, Decl(destructuringAssignmentWithDefault2.ts, 15, 7))
+>a : Symbol(a, Decl(destructuringAssignmentWithDefault2.ts, 0, 5))
+
+const { x: z3 = undefined } = a;
+>x : Symbol(x, Decl(destructuringAssignmentWithDefault2.ts, 0, 10))
+>z3 : Symbol(z3, Decl(destructuringAssignmentWithDefault2.ts, 16, 7))
+>undefined : Symbol(undefined)
+>a : Symbol(a, Decl(destructuringAssignmentWithDefault2.ts, 0, 5))
+
+
+declare const r: Iterator<number>;
+>r : Symbol(r, Decl(destructuringAssignmentWithDefault2.ts, 19, 13))
+>Iterator : Symbol(Iterator, Decl(lib.es2015.iterable.d.ts, --, --))
+
+let done: boolean;
+>done : Symbol(done, Decl(destructuringAssignmentWithDefault2.ts, 20, 3))
+
+let value;
+>value : Symbol(value, Decl(destructuringAssignmentWithDefault2.ts, 21, 3))
+
+({ done = false, value } = r.next());
+>done : Symbol(done, Decl(destructuringAssignmentWithDefault2.ts, 23, 2))
+>value : Symbol(value, Decl(destructuringAssignmentWithDefault2.ts, 23, 16))
+>r.next : Symbol(Iterator.next, Decl(lib.es2015.iterable.d.ts, --, --))
+>r : Symbol(r, Decl(destructuringAssignmentWithDefault2.ts, 19, 13))
+>next : Symbol(Iterator.next, Decl(lib.es2015.iterable.d.ts, --, --))
+
+({ done: done = false, value } = r.next());
+>done : Symbol(done, Decl(destructuringAssignmentWithDefault2.ts, 24, 2))
+>done : Symbol(done, Decl(destructuringAssignmentWithDefault2.ts, 20, 3))
+>value : Symbol(value, Decl(destructuringAssignmentWithDefault2.ts, 24, 22))
+>r.next : Symbol(Iterator.next, Decl(lib.es2015.iterable.d.ts, --, --))
+>r : Symbol(r, Decl(destructuringAssignmentWithDefault2.ts, 19, 13))
+>next : Symbol(Iterator.next, Decl(lib.es2015.iterable.d.ts, --, --))
+

tests/baselines/reference/destructuringAssignmentWithDefault2.types

@@ -0,0 +1,121 @@
+=== tests/cases/compiler/destructuringAssignmentWithDefault2.ts ===
+const a: { x?: number; y?: number } = { };
+>a : { x?: number | undefined; y?: number | undefined; }
+>x : number | undefined
+>y : number | undefined
+>{ } : {}
+
+let x: number;
+>x : number
+
+// Should not error out
+({ x = 0 } = a);
+>({ x = 0 } = a) : { x?: number | undefined; y?: number | undefined; }
+>{ x = 0 } = a : { x?: number | undefined; y?: number | undefined; }
+>{ x = 0 } : { x?: number; }
+>x : number
+>0 : 0
+>a : { x?: number | undefined; y?: number | undefined; }
+
+({ x: x = 0} = a);
+>({ x: x = 0} = a) : { x?: number | undefined; y?: number | undefined; }
+>{ x: x = 0} = a : { x?: number | undefined; y?: number | undefined; }
+>{ x: x = 0} : { x?: number; }
+>x : number
+>x = 0 : 0
+>x : number
+>0 : 0
+>a : { x?: number | undefined; y?: number | undefined; }
+
+({ y: x = 0} = a);
+>({ y: x = 0} = a) : { x?: number | undefined; y?: number | undefined; }
+>{ y: x = 0} = a : { x?: number | undefined; y?: number | undefined; }
+>{ y: x = 0} : { y?: number; }
+>y : number
+>x = 0 : 0
+>x : number
+>0 : 0
+>a : { x?: number | undefined; y?: number | undefined; }
+
+// Should be error
+({ x = undefined } = a);
+>({ x = undefined } = a) : { x?: number | undefined; y?: number | undefined; }
+>{ x = undefined } = a : { x?: number | undefined; y?: number | undefined; }
+>{ x = undefined } : { x?: number; }
+>x : number
+>undefined : undefined
+>a : { x?: number | undefined; y?: number | undefined; }
+
+({ x: x = undefined } = a);
+>({ x: x = undefined } = a) : { x?: number | undefined; y?: number | undefined; }
+>{ x: x = undefined } = a : { x?: number | undefined; y?: number | undefined; }
+>{ x: x = undefined } : { x?: undefined; }
+>x : undefined
+>x = undefined : undefined
+>x : number
+>undefined : undefined
+>a : { x?: number | undefined; y?: number | undefined; }
+
+({ y: x = undefined } = a);
+>({ y: x = undefined } = a) : { x?: number | undefined; y?: number | undefined; }
+>{ y: x = undefined } = a : { x?: number | undefined; y?: number | undefined; }
+>{ y: x = undefined } : { y?: undefined; }
+>y : undefined
+>x = undefined : undefined
+>x : number
+>undefined : undefined
+>a : { x?: number | undefined; y?: number | undefined; }
+
+const { x: z1 } = a;
+>x : any
+>z1 : number | undefined
+>a : { x?: number | undefined; y?: number | undefined; }
+
+const { x: z2 = 0 } = a;
+>x : any
+>z2 : number
+>0 : 0
+>a : { x?: number | undefined; y?: number | undefined; }
+
+const { x: z3 = undefined } = a;
+>x : any
+>z3 : number | undefined
+>undefined : undefined
+>a : { x?: number | undefined; y?: number | undefined; }
+
+
+declare const r: Iterator<number>;
+>r : Iterator<number, any, undefined>
+
+let done: boolean;
+>done : boolean
+
+let value;
+>value : any
+
+({ done = false, value } = r.next());
+>({ done = false, value } = r.next()) : IteratorResult<number, any>
+>{ done = false, value } = r.next() : IteratorResult<number, any>
+>{ done = false, value } : { done?: boolean; value: any; }
+>done : boolean
+>false : false
+>value : any
+>r.next() : IteratorResult<number, any>
+>r.next : (...args: [] | [undefined]) => IteratorResult<number, any>
+>r : Iterator<number, any, undefined>
+>next : (...args: [] | [undefined]) => IteratorResult<number, any>
+
+({ done: done = false, value } = r.next());
+>({ done: done = false, value } = r.next()) : IteratorResult<number, any>
+>{ done: done = false, value } = r.next() : IteratorResult<number, any>
+>{ done: done = false, value } : { done?: boolean; value: any; }
+>done : boolean
+>done = false : false
+>done : boolean
+>false : false
+>value : any
+>r.next() : IteratorResult<number, any>
+>r.next : (...args: [] | [undefined]) => IteratorResult<number, any>
+>r : Iterator<number, any, undefined>
+>next : (...args: [] | [undefined]) => IteratorResult<number, any>
+

tests/cases/compiler/destructuringAssignmentWithDefault2.ts

@@ -0,0 +1,27 @@
+// @lib: es2015
+// @strictNullChecks: true
+const a: { x?: number; y?: number } = { };
+
+let x: number;
+
+// Should not error out
+({ x = 0 } = a);
+({ x: x = 0} = a);
+({ y: x = 0} = a);
+
+// Should be error
+({ x = undefined } = a);
+({ x: x = undefined } = a);
+({ y: x = undefined } = a);
+
+const { x: z1 } = a;
+const { x: z2 = 0 } = a;
+const { x: z3 = undefined } = a;
+
+
+declare const r: Iterator<number>;
+let done: boolean;
+let value;
+
+({ done = false, value } = r.next());
+({ done: done = false, value } = r.next());