Use emptyObjectType for omitted members instead of unknownType (#20940)

* Use emptyObjectType for omitted members instead of unknownType

* Use similar logic as is used for empty arrays for missing elements

src/compiler/checker.ts

@@ -14523,7 +14523,7 @@ namespace ts {
                                 if (patternElement.kind !== SyntaxKind.OmittedExpression) {
                                     error(patternElement, Diagnostics.Initializer_provides_no_value_for_this_binding_element_and_the_binding_element_has_no_default_value);
                                 }
-                                elementTypes.push(unknownType);
+                                elementTypes.push(strictNullChecks ? implicitNeverType : undefinedWideningType);
                             }
                         }
                     }

tests/baselines/reference/declarationEmitDestructuringArrayPattern2.types

@@ -23,7 +23,7 @@ var [a11, b11, c11] = [];
 >a11 : any
 >b11 : any
 >c11 : any
->[] : [any, any, any]
+>[] : [undefined, undefined, undefined]
 
 var [a2, [b2, { x12, y12: c2 }]=["abc", { x12: 10, y12: false }]] = [1, ["hello", { x12: 5, y12: true }]];
 >a2 : number

tests/baselines/reference/declarationsAndAssignments.types

@@ -24,7 +24,7 @@ function f0() {
 >x : number
 >y : string
 >z : any
->[1, "hello"] : [number, string, any]
+>[1, "hello"] : [number, string, undefined]
 >1 : 1
 >"hello" : "hello"
 
@@ -258,13 +258,13 @@ function f8() {
 >a : any
 >b : any
 >c : any
->[] : [any, any, any]
+>[] : [undefined, undefined, undefined]
 
     var [d, e, f] = [1];  // Error, [1] is a tuple
 >d : number
 >e : any
 >f : any
->[1] : [number, any, any]
+>[1] : [number, undefined, undefined]
 >1 : 1
 }
 

tests/baselines/reference/destructuringArrayBindingPatternAndAssignment1ES5.types

@@ -93,18 +93,18 @@ var [c0, c1] = [...temp];
 
 var [c2] = [];
 >c2 : any
->[] : [any]
+>[] : [undefined]
 
 var [[[c3]], [[[[c4]]]]] = [[[]], [[[[]]]]]
 >c3 : any
 >c4 : any
->[[[]], [[[[]]]]] : [[[any]], [[[[any]]]]]
->[[]] : [[any]]
->[] : [any]
->[[[[]]]] : [[[[any]]]]
->[[[]]] : [[[any]]]
->[[]] : [[any]]
->[] : [any]
+>[[[]], [[[[]]]]] : [[[undefined]], [[[[undefined]]]]]
+>[[]] : [[undefined]]
+>[] : [undefined]
+>[[[[]]]] : [[[[undefined]]]]
+>[[[]]] : [[[undefined]]]
+>[[]] : [[undefined]]
+>[] : [undefined]
 
 var [[c5], c6]: [[string|number], boolean] = [[1], true];
 >c5 : string | number

tests/baselines/reference/destructuringArrayBindingPatternAndAssignment1ES5iterable.types

@@ -93,18 +93,18 @@ var [c0, c1] = [...temp];
 
 var [c2] = [];
 >c2 : any
->[] : [any]
+>[] : [undefined]
 
 var [[[c3]], [[[[c4]]]]] = [[[]], [[[[]]]]]
 >c3 : any
 >c4 : any
->[[[]], [[[[]]]]] : [[[any]], [[[[any]]]]]
->[[]] : [[any]]
->[] : [any]
->[[[[]]]] : [[[[any]]]]
->[[[]]] : [[[any]]]
->[[]] : [[any]]
->[] : [any]
+>[[[]], [[[[]]]]] : [[[undefined]], [[[[undefined]]]]]
+>[[]] : [[undefined]]
+>[] : [undefined]
+>[[[[]]]] : [[[[undefined]]]]
+>[[[]]] : [[[undefined]]]
+>[[]] : [[undefined]]
+>[] : [undefined]
 
 var [[c5], c6]: [[string|number], boolean] = [[1], true];
 >c5 : string | number

tests/baselines/reference/destructuringArrayBindingPatternAndAssignment1ES6.types

@@ -93,18 +93,18 @@ var [c0, c1] = [...temp];
 
 var [c2] = [];
 >c2 : any
->[] : [any]
+>[] : [undefined]
 
 var [[[c3]], [[[[c4]]]]] = [[[]], [[[[]]]]]
 >c3 : any
 >c4 : any
->[[[]], [[[[]]]]] : [[[any]], [[[[any]]]]]
->[[]] : [[any]]
->[] : [any]
->[[[[]]]] : [[[[any]]]]
->[[[]]] : [[[any]]]
->[[]] : [[any]]
->[] : [any]
+>[[[]], [[[[]]]]] : [[[undefined]], [[[[undefined]]]]]
+>[[]] : [[undefined]]
+>[] : [undefined]
+>[[[[]]]] : [[[[undefined]]]]
+>[[[]]] : [[[undefined]]]
+>[[]] : [[undefined]]
+>[] : [undefined]
 
 var [[c5], c6]: [[string|number], boolean] = [[1], true];
 >c5 : string | number

tests/baselines/reference/destructuringArrayBindingPatternAndAssignment2.errors.txt

@@ -1,4 +1,6 @@
+tests/cases/conformance/es6/destructuring/destructuringArrayBindingPatternAndAssignment2.ts(3,6): error TS2461: Type 'undefined' is not an array type.
 tests/cases/conformance/es6/destructuring/destructuringArrayBindingPatternAndAssignment2.ts(3,6): error TS2525: Initializer provides no value for this binding element and the binding element has no default value.
+tests/cases/conformance/es6/destructuring/destructuringArrayBindingPatternAndAssignment2.ts(3,12): error TS2461: Type 'undefined' is not an array type.
 tests/cases/conformance/es6/destructuring/destructuringArrayBindingPatternAndAssignment2.ts(3,12): error TS2525: Initializer provides no value for this binding element and the binding element has no default value.
 tests/cases/conformance/es6/destructuring/destructuringArrayBindingPatternAndAssignment2.ts(4,5): error TS2461: Type 'undefined' is not an array type.
 tests/cases/conformance/es6/destructuring/destructuringArrayBindingPatternAndAssignment2.ts(9,5): error TS2322: Type '[number, number, string]' is not assignable to type '[number, boolean, string]'.
@@ -10,13 +12,17 @@ tests/cases/conformance/es6/destructuring/destructuringArrayBindingPatternAndAss
 tests/cases/conformance/es6/destructuring/destructuringArrayBindingPatternAndAssignment2.ts(34,5): error TS2461: Type 'F' is not an array type.
 
 
-==== tests/cases/conformance/es6/destructuring/destructuringArrayBindingPatternAndAssignment2.ts (7 errors) ====
+==== tests/cases/conformance/es6/destructuring/destructuringArrayBindingPatternAndAssignment2.ts (9 errors) ====
     // V is an array assignment pattern, S is the type Any or an array-like type (section 3.3.2), and, for each assignment element E in V,
     //      S is the type Any, or
     var [[a0], [[a1]]] = []         // Error
          ~~~~
+!!! error TS2461: Type 'undefined' is not an array type.
+         ~~~~
 !!! error TS2525: Initializer provides no value for this binding element and the binding element has no default value.
                ~~~~~~
+!!! error TS2461: Type 'undefined' is not an array type.
+               ~~~~~~
 !!! error TS2525: Initializer provides no value for this binding element and the binding element has no default value.
     var [[a2], [[a3]]] = undefined  // Error
         ~~~~~~~~~~~~~~

tests/baselines/reference/destructuringArrayBindingPatternAndAssignment2.types

@@ -4,7 +4,7 @@
 var [[a0], [[a1]]] = []         // Error
 >a0 : any
 >a1 : any
->[] : [any, any]
+>[] : [undefined, undefined]
 
 var [[a2], [[a3]]] = undefined  // Error
 >a2 : any

tests/baselines/reference/destructuringVariableDeclaration1ES5.types

@@ -151,9 +151,9 @@ var {f: [f1, f2, { f3: f4, f5 }, , ]} = { f: [1, 2, { f3: 4, f5: 0 }] };
 >f4 : number
 >f5 : number
 > : undefined
->{ f: [1, 2, { f3: 4, f5: 0 }] } : { f: [number, number, { f3: number; f5: number; }, any]; }
->f : [number, number, { f3: number; f5: number; }, any]
->[1, 2, { f3: 4, f5: 0 }] : [number, number, { f3: number; f5: number; }, any]
+>{ f: [1, 2, { f3: 4, f5: 0 }] } : { f: [number, number, { f3: number; f5: number; }, undefined]; }
+>f : [number, number, { f3: number; f5: number; }, undefined]
+>[1, 2, { f3: 4, f5: 0 }] : [number, number, { f3: number; f5: number; }, undefined]
 >1 : 1
 >2 : 2
 >{ f3: 4, f5: 0 } : { f3: number; f5: number; }

tests/baselines/reference/destructuringVariableDeclaration1ES5iterable.types

@@ -151,9 +151,9 @@ var {f: [f1, f2, { f3: f4, f5 }, , ]} = { f: [1, 2, { f3: 4, f5: 0 }] };
 >f4 : number
 >f5 : number
 > : undefined
->{ f: [1, 2, { f3: 4, f5: 0 }] } : { f: [number, number, { f3: number; f5: number; }, any]; }
->f : [number, number, { f3: number; f5: number; }, any]
->[1, 2, { f3: 4, f5: 0 }] : [number, number, { f3: number; f5: number; }, any]
+>{ f: [1, 2, { f3: 4, f5: 0 }] } : { f: [number, number, { f3: number; f5: number; }, undefined]; }
+>f : [number, number, { f3: number; f5: number; }, undefined]
+>[1, 2, { f3: 4, f5: 0 }] : [number, number, { f3: number; f5: number; }, undefined]
 >1 : 1
 >2 : 2
 >{ f3: 4, f5: 0 } : { f3: number; f5: number; }

tests/baselines/reference/destructuringVariableDeclaration1ES6.types

@@ -151,9 +151,9 @@ var {f: [f1, f2, { f3: f4, f5 }, , ]} = { f: [1, 2, { f3: 4, f5: 0 }] };
 >f4 : number
 >f5 : number
 > : undefined
->{ f: [1, 2, { f3: 4, f5: 0 }] } : { f: [number, number, { f3: number; f5: number; }, any]; }
->f : [number, number, { f3: number; f5: number; }, any]
->[1, 2, { f3: 4, f5: 0 }] : [number, number, { f3: number; f5: number; }, any]
+>{ f: [1, 2, { f3: 4, f5: 0 }] } : { f: [number, number, { f3: number; f5: number; }, undefined]; }
+>f : [number, number, { f3: number; f5: number; }, undefined]
+>[1, 2, { f3: 4, f5: 0 }] : [number, number, { f3: number; f5: number; }, undefined]
 >1 : 1
 >2 : 2
 >{ f3: 4, f5: 0 } : { f3: number; f5: number; }

tests/baselines/reference/downlevelLetConst12.types

@@ -12,7 +12,7 @@ const bar = 1;
 
 let [baz] = [];
 >baz : any
->[] : [any]
+>[] : [undefined]
 
 let {a: baz2} = { a: 1 };
 >a : any
@@ -23,7 +23,7 @@ let {a: baz2} = { a: 1 };
 
 const [baz3] = []
 >baz3 : any
->[] : [any]
+>[] : [undefined]
 
 const {a: baz4} = { a: 1 };
 >a : any

tests/baselines/reference/downlevelLetConst16.types

@@ -516,7 +516,7 @@ function foo3() {
     }
     for (let [y] = []; ;) {
 >y : any
->[] : [any]
+>[] : [undefined]
 
         use(y);
 >use(y) : any
@@ -555,7 +555,7 @@ function foo4() {
     }
     for (const [y] = []; ;) {
 >y : any
->[] : [any]
+>[] : [undefined]
 
         use(y);
 >use(y) : any

tests/baselines/reference/initializedDestructuringAssignmentTypes.errors.txt

@@ -0,0 +1,9 @@
+tests/cases/compiler/initializedDestructuringAssignmentTypes.ts(3,3): error TS2339: Property 'toFixed' does not exist on type 'string'.
+
+
+==== tests/cases/compiler/initializedDestructuringAssignmentTypes.ts (1 errors) ====
+    const [, a = ''] = ''.match('') || [];
+    
+    a.toFixed()
+      ~~~~~~~
+!!! error TS2339: Property 'toFixed' does not exist on type 'string'.

tests/baselines/reference/initializedDestructuringAssignmentTypes.js

@@ -0,0 +1,8 @@
+//// [initializedDestructuringAssignmentTypes.ts]
+const [, a = ''] = ''.match('') || [];
+
+a.toFixed()
+
+//// [initializedDestructuringAssignmentTypes.js]
+var _a = ''.match('') || [], _b = _a[1], a = _b === void 0 ? '' : _b;
+a.toFixed();

tests/baselines/reference/initializedDestructuringAssignmentTypes.symbols

@@ -0,0 +1,9 @@
+=== tests/cases/compiler/initializedDestructuringAssignmentTypes.ts ===
+const [, a = ''] = ''.match('') || [];
+>a : Symbol(a, Decl(initializedDestructuringAssignmentTypes.ts, 0, 8))
+>''.match : Symbol(String.match, Decl(lib.d.ts, --, --))
+>match : Symbol(String.match, Decl(lib.d.ts, --, --))
+
+a.toFixed()
+>a : Symbol(a, Decl(initializedDestructuringAssignmentTypes.ts, 0, 8))
+

tests/baselines/reference/initializedDestructuringAssignmentTypes.types

@@ -0,0 +1,19 @@
+=== tests/cases/compiler/initializedDestructuringAssignmentTypes.ts ===
+const [, a = ''] = ''.match('') || [];
+> : undefined
+>a : string
+>'' : ""
+>''.match('') || [] : RegExpMatchArray | [undefined, ""]
+>''.match('') : RegExpMatchArray
+>''.match : (regexp: string | RegExp) => RegExpMatchArray
+>'' : ""
+>match : (regexp: string | RegExp) => RegExpMatchArray
+>'' : ""
+>[] : [undefined, ""]
+
+a.toFixed()
+>a.toFixed() : any
+>a.toFixed : any
+>a : string
+>toFixed : any
+

tests/cases/compiler/initializedDestructuringAssignmentTypes.ts

@@ -0,0 +1,3 @@
+const [, a = ''] = ''.match('') || [];
+
+a.toFixed()