[parser] report errors for invalid binding patterns in async formal parameters

BUG=v8:4483, v8:5190

R=caitp@igalia.com, nikolaos@chromium.org

Review-Url: https://codereview.chromium.org/2139063002
Cr-Commit-Position: refs/heads/master@{#37691}

src/parsing/parser-base.h

@@ -2827,16 +2827,30 @@ ParserBase<Traits>::ParseLeftHandSideExpression(
           }
         }
         Scanner::Location spread_pos;
-        typename Traits::Type::ExpressionList args =
-            ParseArguments(&spread_pos, is_async, classifier, CHECK_OK);
-
-        if (V8_UNLIKELY(is_async && peek() == Token::ARROW)) {
+        typename Traits::Type::ExpressionList args;
+        if (V8_UNLIKELY(is_async)) {
+          ExpressionClassifier async_classifier(this);
+          args = ParseArguments(&spread_pos, true, &async_classifier, CHECK_OK);
+          if (peek() == Token::ARROW) {
+            ValidateBindingPattern(&async_classifier, CHECK_OK);
+            if (!async_classifier.is_valid_async_arrow_formal_parameters()) {
+              ReportClassifierError(
+                  async_classifier.async_arrow_formal_parameters_error());
+              *ok = false;
+              return this->EmptyExpression();
+            }
             if (args->length()) {
               // async ( Arguments ) => ...
               return Traits::ExpressionListToExpression(args);
             }
             // async () => ...
             return factory()->NewEmptyParentheses(pos);
+          } else {
+            classifier->Accumulate(&async_classifier,
+                                   ExpressionClassifier::AllProductions);
+          }
+        } else {
+          args = ParseArguments(&spread_pos, false, classifier, CHECK_OK);
         }
 
         ArrowFormalParametersUnexpectedToken(classifier);

test/cctest/test-parsing.cc

@@ -7726,6 +7726,14 @@ TEST(AsyncAwaitErrors) {
     "var f = async(await) => 1;",
     "var f = async(await = 1) => 1;",
     "var f = async(...[await]) => 1;",
+
+    // v8:5190
+    "var f = async(1) => 1",
+    "var f = async('str') => 1",
+    "var f = async(/foo/) => 1",
+    "var f = async({ foo = async(1) => 1 }) => 1",
+    "var f = async({ foo = async(a) => 1 })",
+
     NULL
   };
   // clang-format on