Disallow binding patterns in binding rest elements (fixes #2519)

src/compiler/checker.ts

@@ -12729,6 +12729,11 @@ module ts {
                 if (node !== elements[elements.length - 1]) {
                     return grammarErrorOnNode(node, Diagnostics.A_rest_element_must_be_last_in_an_array_destructuring_pattern);
                 }
+
+                if (node.name.kind === SyntaxKind.ArrayBindingPattern || node.name.kind === SyntaxKind.ObjectBindingPattern) {
+                    return grammarErrorOnNode(node.name, Diagnostics.A_rest_element_cannot_contain_a_binding_pattern);
+                }
+
                 if (node.initializer) {
                     // Error on equals token which immediate precedes the initializer
                     return grammarErrorAtPos(getSourceFileOfNode(node), node.initializer.pos - 1, 1, Diagnostics.A_rest_element_cannot_have_an_initializer);

src/compiler/diagnosticInformationMap.generated.ts

@@ -363,6 +363,7 @@ module ts {
         External_module_0_uses_export_and_cannot_be_used_with_export_Asterisk: { code: 2498, category: DiagnosticCategory.Error, key: "External module '{0}' uses 'export =' and cannot be used with 'export *'." },
         An_interface_can_only_extend_an_identifier_Slashqualified_name_with_optional_type_arguments: { code: 2499, category: DiagnosticCategory.Error, key: "An interface can only extend an identifier/qualified-name with optional type arguments." },
         A_class_can_only_implement_an_identifier_Slashqualified_name_with_optional_type_arguments: { code: 2500, category: DiagnosticCategory.Error, key: "A class can only implement an identifier/qualified-name with optional type arguments." },
+        A_rest_element_cannot_contain_a_binding_pattern: { code: 2501, category: DiagnosticCategory.Error, key: "A rest element cannot contain a binding pattern." },
         Import_declaration_0_is_using_private_name_1: { code: 4000, category: DiagnosticCategory.Error, key: "Import declaration '{0}' is using private name '{1}'." },
         Type_parameter_0_of_exported_class_has_or_is_using_private_name_1: { code: 4002, category: DiagnosticCategory.Error, key: "Type parameter '{0}' of exported class has or is using private name '{1}'." },
         Type_parameter_0_of_exported_interface_has_or_is_using_private_name_1: { code: 4004, category: DiagnosticCategory.Error, key: "Type parameter '{0}' of exported interface has or is using private name '{1}'." },

src/compiler/diagnosticMessages.json

@@ -1439,6 +1439,10 @@
         "category": "Error",
         "code": 2500
     },
+    "A rest element cannot contain a binding pattern.": {
+        "category": "Error",
+        "code": 2501
+    },
 
     "Import declaration '{0}' is using private name '{1}'.": {
         "category": "Error",

tests/baselines/reference/restElementWithBindingPattern.errors.txt

@@ -0,0 +1,7 @@
+tests/cases/conformance/es6/destructuring/restElementWithBindingPattern.ts(1,9): error TS2501: A rest element cannot contain a binding pattern.
+
+
+==== tests/cases/conformance/es6/destructuring/restElementWithBindingPattern.ts (1 errors) ====
+    var [...[a, b]] = [0, 1];
+            ~~~~~~
+!!! error TS2501: A rest element cannot contain a binding pattern.

tests/baselines/reference/restElementWithBindingPattern.js

@@ -0,0 +1,5 @@
+//// [restElementWithBindingPattern.ts]
+var [...[a, b]] = [0, 1];
+
+//// [restElementWithBindingPattern.js]
+var _a = [0, 1], [a, b] = _a.slice(0);

tests/baselines/reference/restElementWithBindingPattern2.errors.txt

@@ -0,0 +1,10 @@
+tests/cases/conformance/es6/destructuring/restElementWithBindingPattern2.ts(1,9): error TS2501: A rest element cannot contain a binding pattern.
+tests/cases/conformance/es6/destructuring/restElementWithBindingPattern2.ts(1,16): error TS2459: Type 'number[]' has no property 'b' and no string index signature.
+
+
+==== tests/cases/conformance/es6/destructuring/restElementWithBindingPattern2.ts (2 errors) ====
+    var [...{0: a, b }] = [0, 1];
+            ~~~~~~~~~~
+!!! error TS2501: A rest element cannot contain a binding pattern.
+                   ~
+!!! error TS2459: Type 'number[]' has no property 'b' and no string index signature.

tests/baselines/reference/restElementWithBindingPattern2.js

@@ -0,0 +1,5 @@
+//// [restElementWithBindingPattern2.ts]
+var [...{0: a, b }] = [0, 1];
+
+//// [restElementWithBindingPattern2.js]
+var _a = [0, 1], { 0: a, b } = _a.slice(0);

tests/cases/conformance/es6/destructuring/restElementWithBindingPattern.ts

@@ -0,0 +1 @@
+var [...[a, b]] = [0, 1];

tests/cases/conformance/es6/destructuring/restElementWithBindingPattern2.ts

@@ -0,0 +1 @@
+var [...{0: a, b }] = [0, 1];