Assignment operator is definite assignment (microsoft#39087)

Co-authored-by: Orta Therox <[email protected]>

Author: Kingwl

src/compiler/utilities.ts

@@ -2594,8 +2594,8 @@ namespace ts {
             switch (parent.kind) {
                 case SyntaxKind.BinaryExpression:
                     const binaryOperator = (<BinaryExpression>parent).operatorToken.kind;
-                    return isAssignmentOperator(binaryOperator) && !isLogicalOrCoalescingAssignmentOperator(binaryOperator) && (<BinaryExpression>parent).left === node ?
-                        binaryOperator === SyntaxKind.EqualsToken ? AssignmentKind.Definite : AssignmentKind.Compound :
+                    return isAssignmentOperator(binaryOperator) && (<BinaryExpression>parent).left === node ?
+                        binaryOperator === SyntaxKind.EqualsToken || isLogicalOrCoalescingAssignmentOperator(binaryOperator) ? AssignmentKind.Definite : AssignmentKind.Compound :
                         AssignmentKind.None;
                 case SyntaxKind.PrefixUnaryExpression:
                 case SyntaxKind.PostfixUnaryExpression:

tests/baselines/reference/logicalAssignment9.js

@@ -0,0 +1,13 @@
+//// [logicalAssignment9.ts]
+declare let x: { a?: boolean };
+
+x.a ??= true;
+x.a &&= false;
+
+
+//// [logicalAssignment9.js]
+"use strict";
+var _a;
+var _b, _c;
+(_a = (_b = x).a) !== null && _a !== void 0 ? _a : (_b.a = true);
+(_c = x).a && (_c.a = false);

tests/baselines/reference/logicalAssignment9.symbols

@@ -0,0 +1,15 @@
+=== tests/cases/conformance/esnext/logicalAssignment/logicalAssignment9.ts ===
+declare let x: { a?: boolean };
+>x : Symbol(x, Decl(logicalAssignment9.ts, 0, 11))
+>a : Symbol(a, Decl(logicalAssignment9.ts, 0, 16))
+
+x.a ??= true;
+>x.a : Symbol(a, Decl(logicalAssignment9.ts, 0, 16))
+>x : Symbol(x, Decl(logicalAssignment9.ts, 0, 11))
+>a : Symbol(a, Decl(logicalAssignment9.ts, 0, 16))
+
+x.a &&= false;
+>x.a : Symbol(a, Decl(logicalAssignment9.ts, 0, 16))
+>x : Symbol(x, Decl(logicalAssignment9.ts, 0, 11))
+>a : Symbol(a, Decl(logicalAssignment9.ts, 0, 16))
+

tests/baselines/reference/logicalAssignment9.types

@@ -0,0 +1,19 @@
+=== tests/cases/conformance/esnext/logicalAssignment/logicalAssignment9.ts ===
+declare let x: { a?: boolean };
+>x : { a?: boolean | undefined; }
+>a : boolean | undefined
+
+x.a ??= true;
+>x.a ??= true : boolean
+>x.a : boolean | undefined
+>x : { a?: boolean | undefined; }
+>a : boolean | undefined
+>true : true
+
+x.a &&= false;
+>x.a &&= false : false | undefined
+>x.a : boolean | undefined
+>x : { a?: boolean | undefined; }
+>a : boolean | undefined
+>false : false
+

tests/cases/conformance/esnext/logicalAssignment/logicalAssignment9.ts

@@ -0,0 +1,5 @@
+// @strict: true
+declare let x: { a?: boolean };
+
+x.a ??= true;
+x.a &&= false;