[parser] don't report error for CoverInitializedNames in async arrow formals

BUG=v8:4483, v8:5148
R=littledan@chromium.org, adamk@chromium.org, jwolfe@igalia.com, nikolaos@chromium.org

Review-Url: https://codereview.chromium.org/2091313002
Cr-Commit-Position: refs/heads/master@{#37260}

src/parsing/parser-base.h

@@ -2160,7 +2160,10 @@ typename Traits::Type::ExpressionList ParserBase<Traits>::ParseArguments(
     ExpressionT argument = this->ParseAssignmentExpression(
         true, classifier, CHECK_OK_CUSTOM(NullExpressionList));
     CheckNoTailCallExpressions(classifier, CHECK_OK_CUSTOM(NullExpressionList));
-    Traits::RewriteNonPattern(classifier, CHECK_OK_CUSTOM(NullExpressionList));
+    if (!maybe_arrow) {
+      Traits::RewriteNonPattern(classifier,
+                                CHECK_OK_CUSTOM(NullExpressionList));
+    }
     if (is_spread) {
       if (!spread_arg.IsValid()) {
         spread_arg.beg_pos = start_pos;
@@ -2197,11 +2200,17 @@ typename Traits::Type::ExpressionList ParserBase<Traits>::ParseArguments(
   }
   *first_spread_arg_loc = spread_arg;
 
-  if ((!maybe_arrow || peek() != Token::ARROW) && spread_arg.IsValid()) {
-    // Unspread parameter sequences are translated into array literals in the
-    // parser. Ensure that the number of materialized literals matches between
-    // the parser and preparser
-    Traits::MaterializeUnspreadArgumentsLiterals(unspread_sequences_count);
+  if (!maybe_arrow || peek() != Token::ARROW) {
+    if (maybe_arrow) {
+      Traits::RewriteNonPattern(classifier,
+                                CHECK_OK_CUSTOM(NullExpressionList));
+    }
+    if (spread_arg.IsValid()) {
+      // Unspread parameter sequences are translated into array literals in the
+      // parser. Ensure that the number of materialized literals matches between
+      // the parser and preparser
+      Traits::MaterializeUnspreadArgumentsLiterals(unspread_sequences_count);
+    }
   }
 
   return result;

test/cctest/test-parsing.cc

@@ -7504,6 +7504,9 @@ TEST(AsyncAwait) {
     "var O = { async 'method'() { await 1; } }",
     "var O = { async 0() { await 1; } }",
     "async function await() {}",
+
+    "var asyncFn = async({ foo = 1 }) => foo;",
+    "var asyncFn = async({ foo = 1 } = {}) => foo;",
     NULL
   };
   // clang-format on
@@ -7665,6 +7668,10 @@ TEST(AsyncAwaitErrors) {
     "(async`foo`.bar => 1)",
     "(async`foo`.bar foo => 1)",
     "(async`foo`.bar () => 1)",
+
+    // v8:5148 assert that errors are still thrown for calls that may have been
+    // async functions
+    "async({ foo = 1 })",
     NULL
   };
 
@@ -7686,6 +7693,22 @@ TEST(AsyncAwaitErrors) {
 
     NULL
   };
+
+  const char* formal_parameters_data[] = {
+    "var f = async({ await }) => 1;",
+    "var f = async({ await = 1 }) => 1;",
+    "var f = async({ await } = {}) => 1;",
+    "var f = async({ await = 1 } = {}) => 1;",
+    "var f = async([await]) => 1;",
+    "var f = async([await] = []) => 1;",
+    "var f = async([await = 1]) => 1;",
+    "var f = async([await = 1] = []) => 1;",
+    "var f = async(...await) => 1;",
+    "var f = async(await) => 1;",
+    "var f = async(await = 1) => 1;",
+    "var f = async(...[await]) => 1;",
+    NULL
+  };
   // clang-format on
 
   static const ParserFlag always_flags[] = {kAllowHarmonyAsyncAwait};
@@ -7693,6 +7716,17 @@ TEST(AsyncAwaitErrors) {
                     arraysize(always_flags));
   RunParserSyncTest(strict_context_data, strict_error_data, kError, NULL, 0,
                     always_flags, arraysize(always_flags));
+  {
+    // TODO(caitp): support these early errors in preparser
+    USE(formal_parameters_data);
+    // const bool kIsModule = false;
+    // const bool kTestPreparser = false;
+    // TODO(caitp): These tests seem to fail test-parsing.cc, even with
+    // test_preparser disabled.
+    // RunParserSyncTest(context_data, formal_parameters_data, kError, NULL, 0,
+    //                 always_flags, arraysize(always_flags), NULL, 0,
+    //                 kIsModule, kTestPreparser);
+  }
 }
 
 TEST(AsyncAwaitModule) {

test/mjsunit/harmony/async-await-basic.js

@@ -343,8 +343,20 @@ assertEquals("async function () {}", async function() {}.toString());
 assertEquals("async x => x", (async x => x).toString());
 assertEquals("async x => { return x }", (async x => { return x }).toString());
 class AsyncMethod { async foo() { } }
-assertEquals("async foo() { }", Function.prototype.toString.call(AsyncMethod.prototype.foo));
-assertEquals("async foo() { }", Function.prototype.toString.call({async foo() { }}.foo));
+assertEquals("async foo() { }",
+             Function.prototype.toString.call(AsyncMethod.prototype.foo));
+assertEquals("async foo() { }",
+             Function.prototype.toString.call({async foo() { }}.foo));
 
 // Async functions are not constructible
 assertThrows(() => class extends (async function() {}) {}, TypeError);
+
+// Regress v8:5148
+assertEqualsAsync("1", () => (async({ a = NaN }) => a)({ a: "1" }));
+assertEqualsAsync(
+    "10", () => (async(foo, { a = NaN }) => foo + a)("1", { a: "0" }));
+assertEqualsAsync("2", () => (async({ a = "2" }) => a)({ a: undefined }));
+assertEqualsAsync(
+    "20", () => (async(foo, { a = "0" }) => foo + a)("2", { a: undefined }));
+assertThrows(() => eval("async({ foo = 1 })"), SyntaxError);
+assertThrows(() => eval("async(a, { foo = 1 })"), SyntaxError);