Add errors for invalid assignments and a trailing '?.'

src/compiler/checker.ts

@@ -24123,13 +24123,17 @@ namespace ts {
             return false;
         }
 
-        function checkReferenceExpression(expr: Expression, invalidReferenceMessage: DiagnosticMessage): boolean {
+        function checkReferenceExpression(expr: Expression, invalidReferenceMessage: DiagnosticMessage, invalidOptionalChainMessage: DiagnosticMessage): boolean {
             // References are combinations of identifiers, parentheses, and property accesses.
             const node = skipOuterExpressions(expr, OuterExpressionKinds.Assertions | OuterExpressionKinds.Parentheses);
             if (node.kind !== SyntaxKind.Identifier && node.kind !== SyntaxKind.PropertyAccessExpression && node.kind !== SyntaxKind.ElementAccessExpression) {
                 error(expr, invalidReferenceMessage);
                 return false;
             }
+            if (node.flags & NodeFlags.OptionalChain) {
+                error(expr, invalidOptionalChainMessage);
+                return false;
+            }
             return true;
         }
 
@@ -24239,7 +24243,10 @@ namespace ts {
                         Diagnostics.An_arithmetic_operand_must_be_of_type_any_number_bigint_or_an_enum_type);
                     if (ok) {
                         // run check only if former checks succeeded to avoid reporting cascading errors
-                        checkReferenceExpression(node.operand, Diagnostics.The_operand_of_an_increment_or_decrement_operator_must_be_a_variable_or_a_property_access);
+                        checkReferenceExpression(
+                            node.operand,
+                            Diagnostics.The_operand_of_an_increment_or_decrement_operator_must_be_a_variable_or_a_property_access,
+                            Diagnostics.The_operand_of_an_increment_or_decrement_operator_may_not_be_an_optional_property_access);
                     }
                     return getUnaryResultType(operandType);
             }
@@ -24257,7 +24264,10 @@ namespace ts {
                 Diagnostics.An_arithmetic_operand_must_be_of_type_any_number_bigint_or_an_enum_type);
             if (ok) {
                 // run check only if former checks succeeded to avoid reporting cascading errors
-                checkReferenceExpression(node.operand, Diagnostics.The_operand_of_an_increment_or_decrement_operator_must_be_a_variable_or_a_property_access);
+                checkReferenceExpression(
+                    node.operand,
+                    Diagnostics.The_operand_of_an_increment_or_decrement_operator_must_be_a_variable_or_a_property_access,
+                    Diagnostics.The_operand_of_an_increment_or_decrement_operator_may_not_be_an_optional_property_access);
             }
             return getUnaryResultType(operandType);
         }
@@ -24507,7 +24517,10 @@ namespace ts {
             const error = target.parent.kind === SyntaxKind.SpreadAssignment ?
                 Diagnostics.The_target_of_an_object_rest_assignment_must_be_a_variable_or_a_property_access :
                 Diagnostics.The_left_hand_side_of_an_assignment_expression_must_be_a_variable_or_a_property_access;
-            if (checkReferenceExpression(target, error)) {
+            const optionalError = target.parent.kind === SyntaxKind.SpreadAssignment ?
+                Diagnostics.The_target_of_an_object_rest_assignment_may_not_be_an_optional_property_access :
+                Diagnostics.The_left_hand_side_of_an_assignment_expression_may_not_be_an_optional_property_access;
+            if (checkReferenceExpression(target, error, optionalError)) {
                 checkTypeAssignableToAndOptionallyElaborate(sourceType, targetType, target, target);
             }
             return sourceType;
@@ -24851,7 +24864,9 @@ namespace ts {
                     // A compound assignment furthermore requires VarExpr to be classified as a reference (section 4.1)
                     // and the type of the non-compound operation to be assignable to the type of VarExpr.
 
-                    if (checkReferenceExpression(left, Diagnostics.The_left_hand_side_of_an_assignment_expression_must_be_a_variable_or_a_property_access)
+                    if (checkReferenceExpression(left, 
+                        Diagnostics.The_left_hand_side_of_an_assignment_expression_must_be_a_variable_or_a_property_access,
+                        Diagnostics.The_left_hand_side_of_an_assignment_expression_may_not_be_an_optional_property_access)
                         && (!isIdentifier(left) || unescapeLeadingUnderscores(left.escapedText) !== "exports")) {
                         // to avoid cascading errors check assignability only if 'isReference' check succeeded and no errors were reported
                         checkTypeAssignableToAndOptionallyElaborate(valueType, leftType, left, right);
@@ -28144,7 +28159,10 @@ namespace ts {
                 }
                 else {
                     const leftType = checkExpression(varExpr);
-                    checkReferenceExpression(varExpr, Diagnostics.The_left_hand_side_of_a_for_of_statement_must_be_a_variable_or_a_property_access);
+                    checkReferenceExpression(
+                        varExpr,
+                        Diagnostics.The_left_hand_side_of_a_for_of_statement_must_be_a_variable_or_a_property_access,
+                        Diagnostics.The_left_hand_side_of_a_for_of_statement_may_not_be_an_optional_property_access);
 
                     // iteratedType will be undefined if the rightType was missing properties/signatures
                     // required to get its iteratedType (like [Symbol.iterator] or next). This may be
@@ -28194,7 +28212,10 @@ namespace ts {
                 }
                 else {
                     // run check only former check succeeded to avoid cascading errors
-                    checkReferenceExpression(varExpr, Diagnostics.The_left_hand_side_of_a_for_in_statement_must_be_a_variable_or_a_property_access);
+                    checkReferenceExpression(
+                        varExpr,
+                        Diagnostics.The_left_hand_side_of_a_for_in_statement_must_be_a_variable_or_a_property_access,
+                        Diagnostics.The_left_hand_side_of_a_for_in_statement_may_not_be_an_optional_property_access);
                 }
             }
 

src/compiler/diagnosticMessages.json

@@ -2697,6 +2697,26 @@
         "category": "Error",
         "code": 2773
     },
+    "The operand of an increment or decrement operator may not be an optional property access.": {
+        "category": "Error",
+        "code": 2774
+    },
+    "The target of an object rest assignment may not be an optional property access.": {
+        "category": "Error",
+        "code": 2775
+    },
+    "The left-hand side of an assignment expression may not be an optional property access.": {
+        "category": "Error",
+        "code": 2776
+    },
+    "The left-hand side of a 'for...in' statement may not be an optional property access.": {
+        "category": "Error",
+        "code": 2777
+    },
+    "The left-hand side of a 'for...of' statement may not be an optional property access.": {
+        "category": "Error",
+        "code": 2778
+    },
 
     "Import declaration '{0}' is using private name '{1}'.": {
         "category": "Error",

src/compiler/parser.ts

@@ -4688,6 +4688,7 @@ namespace ts {
 
         function parseCallExpressionRest(expression: LeftHandSideExpression): LeftHandSideExpression {
             while (true) {
+                noop(ts);
                 expression = parseMemberExpressionRest(expression, /*allowOptionalChain*/ true);
                 const questionDotToken = parseOptionalToken(SyntaxKind.QuestionDotToken);
 
@@ -4732,7 +4733,7 @@ namespace ts {
                     const propertyAccess = createNode(SyntaxKind.PropertyAccessExpression, expression.pos) as PropertyAccessExpression;
                     propertyAccess.expression = expression;
                     propertyAccess.questionDotToken = questionDotToken;
-                    propertyAccess.name = createMissingNode(SyntaxKind.Identifier, /*reportAtCurrentPosition*/ false);
+                    propertyAccess.name = createMissingNode(SyntaxKind.Identifier, /*reportAtCurrentPosition*/ false, Diagnostics.Identifier_expected);
                     propertyAccess.flags |= NodeFlags.OptionalChain;
                     expression = finishNode(propertyAccess);
                 }

tests/baselines/reference/elementAccessChain.3.errors.txt

@@ -0,0 +1,98 @@
+tests/cases/conformance/expressions/optionalChaining/elementAccessChain/elementAccessChain.3.ts(3,1): error TS2774: The operand of an increment or decrement operator may not be an optional property access.
+tests/cases/conformance/expressions/optionalChaining/elementAccessChain/elementAccessChain.3.ts(4,1): error TS2774: The operand of an increment or decrement operator may not be an optional property access.
+tests/cases/conformance/expressions/optionalChaining/elementAccessChain/elementAccessChain.3.ts(5,1): error TS2774: The operand of an increment or decrement operator may not be an optional property access.
+tests/cases/conformance/expressions/optionalChaining/elementAccessChain/elementAccessChain.3.ts(6,1): error TS2774: The operand of an increment or decrement operator may not be an optional property access.
+tests/cases/conformance/expressions/optionalChaining/elementAccessChain/elementAccessChain.3.ts(8,3): error TS2774: The operand of an increment or decrement operator may not be an optional property access.
+tests/cases/conformance/expressions/optionalChaining/elementAccessChain/elementAccessChain.3.ts(9,3): error TS2774: The operand of an increment or decrement operator may not be an optional property access.
+tests/cases/conformance/expressions/optionalChaining/elementAccessChain/elementAccessChain.3.ts(10,3): error TS2774: The operand of an increment or decrement operator may not be an optional property access.
+tests/cases/conformance/expressions/optionalChaining/elementAccessChain/elementAccessChain.3.ts(11,3): error TS2774: The operand of an increment or decrement operator may not be an optional property access.
+tests/cases/conformance/expressions/optionalChaining/elementAccessChain/elementAccessChain.3.ts(13,1): error TS2776: The left-hand side of an assignment expression may not be an optional property access.
+tests/cases/conformance/expressions/optionalChaining/elementAccessChain/elementAccessChain.3.ts(14,1): error TS2776: The left-hand side of an assignment expression may not be an optional property access.
+tests/cases/conformance/expressions/optionalChaining/elementAccessChain/elementAccessChain.3.ts(15,1): error TS2776: The left-hand side of an assignment expression may not be an optional property access.
+tests/cases/conformance/expressions/optionalChaining/elementAccessChain/elementAccessChain.3.ts(16,1): error TS2776: The left-hand side of an assignment expression may not be an optional property access.
+tests/cases/conformance/expressions/optionalChaining/elementAccessChain/elementAccessChain.3.ts(18,6): error TS2777: The left-hand side of a 'for...in' statement may not be an optional property access.
+tests/cases/conformance/expressions/optionalChaining/elementAccessChain/elementAccessChain.3.ts(19,6): error TS2777: The left-hand side of a 'for...in' statement may not be an optional property access.
+tests/cases/conformance/expressions/optionalChaining/elementAccessChain/elementAccessChain.3.ts(20,6): error TS2778: The left-hand side of a 'for...of' statement may not be an optional property access.
+tests/cases/conformance/expressions/optionalChaining/elementAccessChain/elementAccessChain.3.ts(21,6): error TS2778: The left-hand side of a 'for...of' statement may not be an optional property access.
+tests/cases/conformance/expressions/optionalChaining/elementAccessChain/elementAccessChain.3.ts(23,7): error TS2776: The left-hand side of an assignment expression may not be an optional property access.
+tests/cases/conformance/expressions/optionalChaining/elementAccessChain/elementAccessChain.3.ts(24,7): error TS2776: The left-hand side of an assignment expression may not be an optional property access.
+tests/cases/conformance/expressions/optionalChaining/elementAccessChain/elementAccessChain.3.ts(25,7): error TS2775: The target of an object rest assignment may not be an optional property access.
+tests/cases/conformance/expressions/optionalChaining/elementAccessChain/elementAccessChain.3.ts(26,7): error TS2775: The target of an object rest assignment may not be an optional property access.
+tests/cases/conformance/expressions/optionalChaining/elementAccessChain/elementAccessChain.3.ts(27,5): error TS2776: The left-hand side of an assignment expression may not be an optional property access.
+tests/cases/conformance/expressions/optionalChaining/elementAccessChain/elementAccessChain.3.ts(28,5): error TS2776: The left-hand side of an assignment expression may not be an optional property access.
+
+
+==== tests/cases/conformance/expressions/optionalChaining/elementAccessChain/elementAccessChain.3.ts (22 errors) ====
+    declare const obj: any;
+
+    obj?.["a"]++;
+    ~~~~~~~~~~
+!!! error TS2774: The operand of an increment or decrement operator may not be an optional property access.
+    obj?.a["b"]++;
+    ~~~~~~~~~~~
+!!! error TS2774: The operand of an increment or decrement operator may not be an optional property access.
+    obj?.["a"]--;
+    ~~~~~~~~~~
+!!! error TS2774: The operand of an increment or decrement operator may not be an optional property access.
+    obj?.a["b"]--;
+    ~~~~~~~~~~~
+!!! error TS2774: The operand of an increment or decrement operator may not be an optional property access.
+
+    ++obj?.["a"];
+      ~~~~~~~~~~
+!!! error TS2774: The operand of an increment or decrement operator may not be an optional property access.
+    ++obj?.a["b"];
+      ~~~~~~~~~~~
+!!! error TS2774: The operand of an increment or decrement operator may not be an optional property access.
+    --obj?.["a"];
+      ~~~~~~~~~~
+!!! error TS2774: The operand of an increment or decrement operator may not be an optional property access.
+    --obj?.a["b"];
+      ~~~~~~~~~~~
+!!! error TS2774: The operand of an increment or decrement operator may not be an optional property access.
+
+    obj?.["a"] = 1;
+    ~~~~~~~~~~
+!!! error TS2776: The left-hand side of an assignment expression may not be an optional property access.
+    obj?.a["b"] = 1;
+    ~~~~~~~~~~~
+!!! error TS2776: The left-hand side of an assignment expression may not be an optional property access.
+    obj?.["a"] += 1;
+    ~~~~~~~~~~
+!!! error TS2776: The left-hand side of an assignment expression may not be an optional property access.
+    obj?.a["b"] += 1;
+    ~~~~~~~~~~~
+!!! error TS2776: The left-hand side of an assignment expression may not be an optional property access.
+
+    for (obj?.["a"] in {});
+         ~~~~~~~~~~
+!!! error TS2777: The left-hand side of a 'for...in' statement may not be an optional property access.
+    for (obj?.a["b"] in {});
+         ~~~~~~~~~~~
+!!! error TS2777: The left-hand side of a 'for...in' statement may not be an optional property access.
+    for (obj?.["a"] of []);
+         ~~~~~~~~~~
+!!! error TS2778: The left-hand side of a 'for...of' statement may not be an optional property access.
+    for (obj?.a["b"] of []);
+         ~~~~~~~~~~~
+!!! error TS2778: The left-hand side of a 'for...of' statement may not be an optional property access.
+
+    ({ a: obj?.["a"] } = { a: 1 });
+          ~~~~~~~~~~
+!!! error TS2776: The left-hand side of an assignment expression may not be an optional property access.
+    ({ a: obj?.a["b"] } = { a: 1 });
+          ~~~~~~~~~~~
+!!! error TS2776: The left-hand side of an assignment expression may not be an optional property access.
+    ({ ...obj?.["a"] } = { a: 1 });
+          ~~~~~~~~~~
+!!! error TS2775: The target of an object rest assignment may not be an optional property access.
+    ({ ...obj?.a["b"] } = { a: 1 });
+          ~~~~~~~~~~~
+!!! error TS2775: The target of an object rest assignment may not be an optional property access.
+    [...obj?.["a"]] = [];
+        ~~~~~~~~~~
+!!! error TS2776: The left-hand side of an assignment expression may not be an optional property access.
+    [...obj?.a["b"]] = [];
+        ~~~~~~~~~~~
+!!! error TS2776: The left-hand side of an assignment expression may not be an optional property access.
+

tests/baselines/reference/elementAccessChain.3.js

@@ -0,0 +1,75 @@
+//// [elementAccessChain.3.ts]
+declare const obj: any;
+
+obj?.["a"]++;
+obj?.a["b"]++;
+obj?.["a"]--;
+obj?.a["b"]--;
+
+++obj?.["a"];
+++obj?.a["b"];
+--obj?.["a"];
+--obj?.a["b"];
+
+obj?.["a"] = 1;
+obj?.a["b"] = 1;
+obj?.["a"] += 1;
+obj?.a["b"] += 1;
+
+for (obj?.["a"] in {});
+for (obj?.a["b"] in {});
+for (obj?.["a"] of []);
+for (obj?.a["b"] of []);
+
+({ a: obj?.["a"] } = { a: 1 });
+({ a: obj?.a["b"] } = { a: 1 });
+({ ...obj?.["a"] } = { a: 1 });
+({ ...obj?.a["b"] } = { a: 1 });
+[...obj?.["a"]] = [];
+[...obj?.a["b"]] = [];
+
+
+//// [elementAccessChain.3.js]
+"use strict";
+var __rest = (this && this.__rest) || function (s, e) {
+    var t = {};
+    for (var p in s) if (Object.prototype.hasOwnProperty.call(s, p) && e.indexOf(p) < 0)
+        t[p] = s[p];
+    if (s != null && typeof Object.getOwnPropertySymbols === "function")
+        for (var i = 0, p = Object.getOwnPropertySymbols(s); i < p.length; i++) {
+            if (e.indexOf(p[i]) < 0 && Object.prototype.propertyIsEnumerable.call(s, p[i]))
+                t[p[i]] = s[p[i]];
+        }
+    return t;
+};
+var _a, _b, _c, _d, _e, _f, _g, _h, _j, _k, _l, _m, _o, _p, _q, _r, _s, _t, _u, _v, _w, _x;
+((_a = obj) === null || _a === void 0 ? void 0 : _a["a"])++;
+((_b = obj) === null || _b === void 0 ? void 0 : _b.a["b"])++;
+((_c = obj) === null || _c === void 0 ? void 0 : _c["a"])--;
+((_d = obj) === null || _d === void 0 ? void 0 : _d.a["b"])--;
+++((_e = obj) === null || _e === void 0 ? void 0 : _e["a"]);
+++((_f = obj) === null || _f === void 0 ? void 0 : _f.a["b"]);
+--((_g = obj) === null || _g === void 0 ? void 0 : _g["a"]);
+--((_h = obj) === null || _h === void 0 ? void 0 : _h.a["b"]);
+(_j = obj) === null || _j === void 0 ? void 0 : _j["a"] = 1;
+(_k = obj) === null || _k === void 0 ? void 0 : _k.a["b"] = 1;
+(_l = obj) === null || _l === void 0 ? void 0 : _l["a"] += 1;
+(_m = obj) === null || _m === void 0 ? void 0 : _m.a["b"] += 1;
+for ((_o = obj) === null || _o === void 0 ? void 0 : _o["a"] in {})
+    ;
+for ((_p = obj) === null || _p === void 0 ? void 0 : _p.a["b"] in {})
+    ;
+for (var _i = 0, _y = []; _i < _y.length; _i++) {
+    (_q = obj) === null || _q === void 0 ? void 0 : _q["a"] = _y[_i];
+    ;
+}
+for (var _z = 0, _0 = []; _z < _0.length; _z++) {
+    (_r = obj) === null || _r === void 0 ? void 0 : _r.a["b"] = _0[_z];
+    ;
+}
+((_s = obj) === null || _s === void 0 ? void 0 : _s["a"] = { a: 1 }.a);
+((_t = obj) === null || _t === void 0 ? void 0 : _t.a["b"] = { a: 1 }.a);
+((_u = obj) === null || _u === void 0 ? void 0 : _u["a"] = __rest({ a: 1 }, []));
+((_v = obj) === null || _v === void 0 ? void 0 : _v.a["b"] = __rest({ a: 1 }, []));
+(_w = obj) === null || _w === void 0 ? void 0 : _w["a"] = [].slice(0);
+(_x = obj) === null || _x === void 0 ? void 0 : _x.a["b"] = [].slice(0);