test_encoder passes! Other tests still need to be fixed.

2 files changed, 4 insertions, 2 deletions

diff --git a/upbc/generator.cc b/upbc/generator.cc
index bb29041..68996a9 100644
--- a/upbc/generator.cc
+++ b/upbc/generator.cc
@@ -521,7 +521,7 @@ void WriteSource(const protobuf::FileDescriptor* file, Output& output) {
         }
 
         if (MessageLayout::HasHasbit(field)) {
-          presence = absl::StrCat(layout.GetHasbitIndex(field) + 1);
+          presence = absl::StrCat(layout.GetHasbitIndex(field));
         } else if (field->containing_oneof()) {
           MessageLayout::Size case_offset =
               layout.GetOneofCaseOffset(field->containing_oneof());
diff --git a/upbc/message_layout.cc b/upbc/message_layout.cc
index 5956424..f0a6872 100644
--- a/upbc/message_layout.cc
+++ b/upbc/message_layout.cc
@@ -130,7 +130,9 @@ void MessageLayout::PlaceNonOneofFields(
   int hasbit_count = 0;
   for (auto field : field_order) {
     if (HasHasbit(field)) {
-      hasbit_indexes_[field] = hasbit_count++;
+      // We don't use hasbit 0, so that 0 can indicate "no presence" in the
+      // table. This wastes one hasbit, but we don't worry about it for now.
+      hasbit_indexes_[field] = ++hasbit_count;
     }
   }