fix #11480, disallow delete operator on readonly property or index signature

src/compiler/checker.ts

@@ -6072,7 +6072,7 @@ namespace ts {
                     getIndexInfoOfType(objectType, IndexKind.String) ||
                     undefined;
                 if (indexInfo) {
-                    if (accessExpression && isAssignmentTarget(accessExpression) && indexInfo.isReadonly) {
+                    if (accessExpression && indexInfo.isReadonly && (isAssignmentTarget(accessExpression) || isDeleteTarget(accessExpression))) {
                         error(accessExpression, Diagnostics.Index_signature_in_type_0_only_permits_reading, typeToString(objectType));
                         return unknownType;
                     }
@@ -14386,6 +14386,16 @@ namespace ts {
 
         function checkDeleteExpression(node: DeleteExpression): Type {
             checkExpression(node.expression);
+            const expr = skipParentheses(node.expression);
+            if (expr.kind !== SyntaxKind.PropertyAccessExpression && expr.kind !== SyntaxKind.ElementAccessExpression) {
+                error(expr, Diagnostics.The_operand_of_a_delete_operator_must_be_a_property_reference);
+                return booleanType;
+            }
+            const links = getNodeLinks(expr);
+            const symbol = getExportSymbolOfValueSymbolIfExported(links.resolvedSymbol);
+            if (symbol && isReadonlySymbol(symbol)) {
+                error(expr, Diagnostics.The_operand_of_a_delete_operator_cannot_be_a_read_only_property);
+            }
             return booleanType;
         }
 

src/compiler/diagnosticMessages.json

@@ -2019,6 +2019,14 @@
         "category": "Error",
         "code": 2702
     },
+    "The operand of a delete operator must be a property reference": {
+        "category": "Error",
+        "code": 2703
+    },
+    "The operand of a delete operator cannot be a read-only property": {
+        "category": "Error",
+        "code": 2704
+    },
 
     "Import declaration '{0}' is using private name '{1}'.": {
         "category": "Error",

src/compiler/utilities.ts

@@ -1,4 +1,4 @@
-/// <reference path="sys.ts" />
+/// <reference path="sys.ts" />
 
 /* @internal */
 namespace ts {
@@ -1668,6 +1668,18 @@ namespace ts {
         return getAssignmentTargetKind(node) !== AssignmentKind.None;
     }
 
+    // a node is delete target iff. it is PropertyAccessExpression/ElementAccessExpression with parentheses skipped
+    export function isDeleteTarget(node: Node): boolean {
+        if (node.kind !== SyntaxKind.PropertyAccessExpression && node.kind !== SyntaxKind.ElementAccessExpression) {
+            return false;
+        }
+        node = node.parent;
+        while (node && node.kind === SyntaxKind.ParenthesizedExpression) {
+            node = node.parent;
+        }
+        return node && node.kind === SyntaxKind.DeleteExpression;
+    }
+
     export function isNodeDescendantOf(node: Node, ancestor: Node): boolean {
         while (node) {
             if (node === ancestor) return true;

tests/baselines/reference/await_unaryExpression_es2017_1.errors.txt

@@ -0,0 +1,29 @@
+tests/cases/conformance/async/es2017/await_unaryExpression_es2017_1.ts(7,12): error TS2703: The operand of a delete operator must be a property reference
+tests/cases/conformance/async/es2017/await_unaryExpression_es2017_1.ts(11,12): error TS2703: The operand of a delete operator must be a property reference
+
+
+==== tests/cases/conformance/async/es2017/await_unaryExpression_es2017_1.ts (2 errors) ====
+
+    async function bar() {
+        !await 42; // OK
+    }
+
+    async function bar1() {
+        delete await 42; // OK
+               ~~~~~~~~
+!!! error TS2703: The operand of a delete operator must be a property reference
+    }
+
+    async function bar2() {
+        delete await 42; // OK
+               ~~~~~~~~
+!!! error TS2703: The operand of a delete operator must be a property reference
+    }
+
+    async function bar3() {
+        void await 42;
+    }
+
+    async function bar4() {
+        +await 42;
+    }

tests/baselines/reference/await_unaryExpression_es2017_2.errors.txt

@@ -0,0 +1,21 @@
+tests/cases/conformance/async/es2017/await_unaryExpression_es2017_2.ts(3,12): error TS2703: The operand of a delete operator must be a property reference
+tests/cases/conformance/async/es2017/await_unaryExpression_es2017_2.ts(7,12): error TS2703: The operand of a delete operator must be a property reference
+
+
+==== tests/cases/conformance/async/es2017/await_unaryExpression_es2017_2.ts (2 errors) ====
+
+    async function bar1() {
+        delete await 42;
+               ~~~~~~~~
+!!! error TS2703: The operand of a delete operator must be a property reference
+    }
+
+    async function bar2() {
+        delete await 42;
+               ~~~~~~~~
+!!! error TS2703: The operand of a delete operator must be a property reference
+    }
+
+    async function bar3() {
+        void await 42;
+    }

tests/baselines/reference/await_unaryExpression_es6_1.errors.txt

@@ -0,0 +1,29 @@
+tests/cases/conformance/async/es6/await_unaryExpression_es6_1.ts(7,12): error TS2703: The operand of a delete operator must be a property reference
+tests/cases/conformance/async/es6/await_unaryExpression_es6_1.ts(11,12): error TS2703: The operand of a delete operator must be a property reference
+
+
+==== tests/cases/conformance/async/es6/await_unaryExpression_es6_1.ts (2 errors) ====
+
+    async function bar() {
+        !await 42; // OK
+    }
+
+    async function bar1() {
+        delete await 42; // OK
+               ~~~~~~~~
+!!! error TS2703: The operand of a delete operator must be a property reference
+    }
+
+    async function bar2() {
+        delete await 42; // OK
+               ~~~~~~~~
+!!! error TS2703: The operand of a delete operator must be a property reference
+    }
+
+    async function bar3() {
+        void await 42;
+    }
+
+    async function bar4() {
+        +await 42;
+    }

tests/baselines/reference/await_unaryExpression_es6_2.errors.txt

@@ -0,0 +1,21 @@
+tests/cases/conformance/async/es6/await_unaryExpression_es6_2.ts(3,12): error TS2703: The operand of a delete operator must be a property reference
+tests/cases/conformance/async/es6/await_unaryExpression_es6_2.ts(7,12): error TS2703: The operand of a delete operator must be a property reference
+
+
+==== tests/cases/conformance/async/es6/await_unaryExpression_es6_2.ts (2 errors) ====
+
+    async function bar1() {
+        delete await 42;
+               ~~~~~~~~
+!!! error TS2703: The operand of a delete operator must be a property reference
+    }
+
+    async function bar2() {
+        delete await 42;
+               ~~~~~~~~
+!!! error TS2703: The operand of a delete operator must be a property reference
+    }
+
+    async function bar3() {
+        void await 42;
+    }

tests/baselines/reference/computedPropertyNames3_ES5.errors.txt

@@ -2,12 +2,13 @@ tests/cases/conformance/es6/computedProperties/computedPropertyNames3_ES5.ts(4,1
 tests/cases/conformance/es6/computedProperties/computedPropertyNames3_ES5.ts(5,9): error TS2378: A 'get' accessor must return a value.
 tests/cases/conformance/es6/computedProperties/computedPropertyNames3_ES5.ts(5,9): error TS2464: A computed property name must be of type 'string', 'number', 'symbol', or 'any'.
 tests/cases/conformance/es6/computedProperties/computedPropertyNames3_ES5.ts(5,17): error TS1102: 'delete' cannot be called on an identifier in strict mode.
+tests/cases/conformance/es6/computedProperties/computedPropertyNames3_ES5.ts(5,17): error TS2703: The operand of a delete operator must be a property reference
 tests/cases/conformance/es6/computedProperties/computedPropertyNames3_ES5.ts(6,9): error TS2464: A computed property name must be of type 'string', 'number', 'symbol', or 'any'.
 tests/cases/conformance/es6/computedProperties/computedPropertyNames3_ES5.ts(7,16): error TS2378: A 'get' accessor must return a value.
 tests/cases/conformance/es6/computedProperties/computedPropertyNames3_ES5.ts(7,16): error TS2464: A computed property name must be of type 'string', 'number', 'symbol', or 'any'.
 
 
-==== tests/cases/conformance/es6/computedProperties/computedPropertyNames3_ES5.ts (7 errors) ====
+==== tests/cases/conformance/es6/computedProperties/computedPropertyNames3_ES5.ts (8 errors) ====
     var id;
     class C {
         [0 + 1]() { }
@@ -21,6 +22,8 @@ tests/cases/conformance/es6/computedProperties/computedPropertyNames3_ES5.ts(7,1
 !!! error TS2464: A computed property name must be of type 'string', 'number', 'symbol', or 'any'.
                     ~~
 !!! error TS1102: 'delete' cannot be called on an identifier in strict mode.
+                    ~~
+!!! error TS2703: The operand of a delete operator must be a property reference
         set [[0, 1]](v) { }
             ~~~~~~~~
 !!! error TS2464: A computed property name must be of type 'string', 'number', 'symbol', or 'any'.

tests/baselines/reference/computedPropertyNames3_ES6.errors.txt

@@ -2,12 +2,13 @@ tests/cases/conformance/es6/computedProperties/computedPropertyNames3_ES6.ts(4,1
 tests/cases/conformance/es6/computedProperties/computedPropertyNames3_ES6.ts(5,9): error TS2378: A 'get' accessor must return a value.
 tests/cases/conformance/es6/computedProperties/computedPropertyNames3_ES6.ts(5,9): error TS2464: A computed property name must be of type 'string', 'number', 'symbol', or 'any'.
 tests/cases/conformance/es6/computedProperties/computedPropertyNames3_ES6.ts(5,17): error TS1102: 'delete' cannot be called on an identifier in strict mode.
+tests/cases/conformance/es6/computedProperties/computedPropertyNames3_ES6.ts(5,17): error TS2703: The operand of a delete operator must be a property reference
 tests/cases/conformance/es6/computedProperties/computedPropertyNames3_ES6.ts(6,9): error TS2464: A computed property name must be of type 'string', 'number', 'symbol', or 'any'.
 tests/cases/conformance/es6/computedProperties/computedPropertyNames3_ES6.ts(7,16): error TS2378: A 'get' accessor must return a value.
 tests/cases/conformance/es6/computedProperties/computedPropertyNames3_ES6.ts(7,16): error TS2464: A computed property name must be of type 'string', 'number', 'symbol', or 'any'.
 
 
-==== tests/cases/conformance/es6/computedProperties/computedPropertyNames3_ES6.ts (7 errors) ====
+==== tests/cases/conformance/es6/computedProperties/computedPropertyNames3_ES6.ts (8 errors) ====
     var id;
     class C {
         [0 + 1]() { }
@@ -21,6 +22,8 @@ tests/cases/conformance/es6/computedProperties/computedPropertyNames3_ES6.ts(7,1
 !!! error TS2464: A computed property name must be of type 'string', 'number', 'symbol', or 'any'.
                     ~~
 !!! error TS1102: 'delete' cannot be called on an identifier in strict mode.
+                    ~~
+!!! error TS2703: The operand of a delete operator must be a property reference
         set [[0, 1]](v) { }
             ~~~~~~~~
 !!! error TS2464: A computed property name must be of type 'string', 'number', 'symbol', or 'any'.

tests/baselines/reference/controlFlowDeleteOperator.errors.txt

@@ -0,0 +1,23 @@
+tests/cases/conformance/controlFlow/controlFlowDeleteOperator.ts(15,12): error TS2703: The operand of a delete operator must be a property reference
+
+
+==== tests/cases/conformance/controlFlow/controlFlowDeleteOperator.ts (1 errors) ====
+
+    function f() {
+        let x: { a?: number | string, b: number | string } = { b: 1 };
+        x.a;
+        x.b;
+        x.a = 1;
+        x.b = 1;
+        x.a;
+        x.b;
+        delete x.a;
+        delete x.b;
+        x.a;
+        x.b;
+        x;
+        delete x;  // No effect
+               ~
+!!! error TS2703: The operand of a delete operator must be a property reference
+        x;
+    }

tests/baselines/reference/deleteOperator1.errors.txt

@@ -1,10 +1,19 @@
+tests/cases/compiler/deleteOperator1.ts(2,25): error TS2703: The operand of a delete operator must be a property reference
+tests/cases/compiler/deleteOperator1.ts(3,21): error TS2703: The operand of a delete operator must be a property reference
 tests/cases/compiler/deleteOperator1.ts(4,5): error TS2322: Type 'boolean' is not assignable to type 'number'.
+tests/cases/compiler/deleteOperator1.ts(4,24): error TS2703: The operand of a delete operator must be a property reference
 
 
-==== tests/cases/compiler/deleteOperator1.ts (1 errors) ====
+==== tests/cases/compiler/deleteOperator1.ts (4 errors) ====
     var a;
     var x: boolean = delete a;
+                            ~
+!!! error TS2703: The operand of a delete operator must be a property reference
     var y: any = delete a;
+                        ~
+!!! error TS2703: The operand of a delete operator must be a property reference
     var z: number = delete a;
         ~
-!!! error TS2322: Type 'boolean' is not assignable to type 'number'.
+!!! error TS2322: Type 'boolean' is not assignable to type 'number'.
+                           ~
+!!! error TS2703: The operand of a delete operator must be a property reference

tests/baselines/reference/deleteOperatorInStrictMode.errors.txt

@@ -1,9 +1,12 @@
 tests/cases/compiler/deleteOperatorInStrictMode.ts(3,8): error TS1102: 'delete' cannot be called on an identifier in strict mode.
+tests/cases/compiler/deleteOperatorInStrictMode.ts(3,8): error TS2703: The operand of a delete operator must be a property reference
 
 
-==== tests/cases/compiler/deleteOperatorInStrictMode.ts (1 errors) ====
+==== tests/cases/compiler/deleteOperatorInStrictMode.ts (2 errors) ====
     "use strict"
     var a;
     delete a;
            ~
-!!! error TS1102: 'delete' cannot be called on an identifier in strict mode.
+!!! error TS1102: 'delete' cannot be called on an identifier in strict mode.
+           ~
+!!! error TS2703: The operand of a delete operator must be a property reference

tests/baselines/reference/deleteOperatorInvalidOperations.errors.txt

@@ -1,22 +1,29 @@
 tests/cases/conformance/expressions/unaryOperators/deleteOperator/deleteOperatorInvalidOperations.ts(5,20): error TS1005: ',' expected.
+tests/cases/conformance/expressions/unaryOperators/deleteOperator/deleteOperatorInvalidOperations.ts(5,26): error TS2703: The operand of a delete operator must be a property reference
 tests/cases/conformance/expressions/unaryOperators/deleteOperator/deleteOperatorInvalidOperations.ts(5,27): error TS1109: Expression expected.
+tests/cases/conformance/expressions/unaryOperators/deleteOperator/deleteOperatorInvalidOperations.ts(8,22): error TS2703: The operand of a delete operator must be a property reference
 tests/cases/conformance/expressions/unaryOperators/deleteOperator/deleteOperatorInvalidOperations.ts(8,23): error TS1109: Expression expected.
 tests/cases/conformance/expressions/unaryOperators/deleteOperator/deleteOperatorInvalidOperations.ts(13,16): error TS1102: 'delete' cannot be called on an identifier in strict mode.
+tests/cases/conformance/expressions/unaryOperators/deleteOperator/deleteOperatorInvalidOperations.ts(13,16): error TS2703: The operand of a delete operator must be a property reference
 
 
-==== tests/cases/conformance/expressions/unaryOperators/deleteOperator/deleteOperatorInvalidOperations.ts (4 errors) ====
+==== tests/cases/conformance/expressions/unaryOperators/deleteOperator/deleteOperatorInvalidOperations.ts (7 errors) ====
     // Unary operator delete
     var ANY;
 
     // operand before delete operator
     var BOOLEAN1 = ANY delete ;     //expect error
                        ~~~~~~
 !!! error TS1005: ',' expected.
+
+!!! error TS2703: The operand of a delete operator must be a property reference
                               ~
 !!! error TS1109: Expression expected.
 
     // miss an operand
     var BOOLEAN2 = delete ;
+
+!!! error TS2703: The operand of a delete operator must be a property reference
                           ~
 !!! error TS1109: Expression expected.
 
@@ -26,5 +33,7 @@ tests/cases/conformance/expressions/unaryOperators/deleteOperator/deleteOperator
             delete s;      //expect error
                    ~
 !!! error TS1102: 'delete' cannot be called on an identifier in strict mode.
+                   ~
+!!! error TS2703: The operand of a delete operator must be a property reference
         }
     }