[torque] Only check ParseResultIterator after non-exceptional control flow

We sometimes use ReportError() inside of Torque parser actions.
The resulting exception prevented the ParseResultIterator from being
consumed completely, which in turn triggered a CHECK failure instead
of the correct error message.

Change-Id: Ie8dcdf67094e5ad5d68934e8a2921d5f52bd3092
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3306973
Commit-Queue: Nico Hartmann <nicohartmann@chromium.org>
Auto-Submit: Tobias Tebbi <tebbi@chromium.org>
Reviewed-by: Nico Hartmann <nicohartmann@chromium.org>
Cr-Commit-Position: refs/heads/main@{#78184}

src/torque/earley-parser.cc

@@ -54,7 +54,10 @@ base::Optional<ParseResult> Rule::RunAction(const Item* completed_item,
   MatchedInput matched_input = completed_item->GetMatchedInput(tokens);
   CurrentSourcePosition::Scope pos_scope(matched_input.pos);
   ParseResultIterator iterator(std::move(results), matched_input);
-  return action_(&iterator);
+  auto result = action_(&iterator);
+  // Make sure the parse action consumed all the child results.
+  CHECK(!iterator.HasNext());
+  return result;
 }
 
 Symbol& Symbol::operator=(std::initializer_list<Rule> rules) {

src/torque/earley-parser.h

@@ -163,10 +163,7 @@ class ParseResultIterator {
   explicit ParseResultIterator(std::vector<ParseResult> results,
                                MatchedInput matched_input)
       : results_(std::move(results)), matched_input_(matched_input) {}
-  ~ParseResultIterator() {
-    // Check that all parse results have been used.
-    CHECK_EQ(results_.size(), i_);
-  }
+
   ParseResultIterator(const ParseResultIterator&) = delete;
   ParseResultIterator& operator=(const ParseResultIterator&) = delete;