LibJS: Rest parameter in setter functions is a syntax error

Author: linusg

Libraries/LibJS/Parser.cpp

@@ -1278,7 +1278,7 @@ Vector<FunctionNode::Parameter> Parser::parse_function_parameters(int& function_
     while (match(TokenType::Identifier) || match(TokenType::TripleDot)) {
         if (parse_options & FunctionNodeParseOptions::IsGetterFunction)
             syntax_error("Getter function must have no arguments");
-        if (parse_options & FunctionNodeParseOptions::IsSetterFunction && parameters.size() >= 1)
+        if (parse_options & FunctionNodeParseOptions::IsSetterFunction && (parameters.size() >= 1 || match(TokenType::TripleDot)))
             syntax_error("Setter function must have one argument");
         if (match(TokenType::TripleDot)) {
             consume();

Libraries/LibJS/Tests/classes/class-errors.js

@@ -70,6 +70,11 @@ describe("syntax errors", () => {
     class A {
       set foo(bar, baz) {
       }
+    }`).not.toEval();
+        expect(`
+    class A {
+      set foo(...bar) {
+      }
     }`).not.toEval();
     });
 

Libraries/LibJS/Tests/object-basic.js

@@ -151,6 +151,7 @@ describe("errors", () => {
         expect("({ get ...[foo] })").not.toEval();
         expect("({ get foo(bar) {} })").not.toEval();
         expect("({ set foo() {} })").not.toEval();
+        expect("({ set foo(...bar) {} })").not.toEval();
         expect("({ set foo(bar, baz) {} })").not.toEval();
         expect("({ ...foo: bar })").not.toEval();
     });