[Python] descriptor_database: items are added with key starting with dot

[mcepl]

What version of protobuf and what language are you using?
Version: 3.20.1
Language: Python

What operating system (Linux, Windows, ...) and version?
Linux/openSUSE/Tumbleweed, all packages from the current distribution

What runtime / compiler are you using (e.g., python version or gcc version)
See details in googleapis/python-api-core#372

What did you do?
Run test suite for python-api-core, while packaging it for openSUSE..

What did you expect to see
Passing test suite.

What did you see instead?
See the above mentioned bug.

Make sure you include information that can help us debug (full error message, exception listing, stack trace, logs).
In the end I have created this patch, which makes the test suite pass, but I guess it is just poorly mitigating bug somewhere else in the code:

---
 python/google/protobuf/descriptor_database.py |    9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

--- a/python/google/protobuf/descriptor_database.py
+++ b/python/google/protobuf/descriptor_database.py
@@ -75,14 +75,17 @@ class DescriptorDatabase(object):
       for name in _ExtractSymbols(message, package):
         self._AddSymbol(name, file_desc_proto)
     for enum in file_desc_proto.enum_type:
-      self._AddSymbol(('.'.join((package, enum.name))), file_desc_proto)
+      symbol = ('.'.join((package, enum.name))).lstrip('.')
+      self._AddSymbol(symbol, file_desc_proto)
       for enum_value in enum.value:
         self._file_desc_protos_by_symbol[
             '.'.join((package, enum_value.name))] = file_desc_proto
     for extension in file_desc_proto.extension:
-      self._AddSymbol(('.'.join((package, extension.name))), file_desc_proto)
+      symbol = ('.'.join((package, extension.name))).lstrip('.')
+      self._AddSymbol(symbol, file_desc_proto)
     for service in file_desc_proto.service:
-      self._AddSymbol(('.'.join((package, service.name))), file_desc_proto)
+      symbol = ('.'.join((package, service.name))).lstrip('.')
+      self._AddSymbol(symbol, file_desc_proto)

   def FindFileByName(self, name):
     """Finds the file descriptor proto by file name.

[anandolee]

It only happens when package is empty.

The .proto file starts with a package declaration, which helps to prevent naming conflicts between different projects. In Python, packages are normally determined by directory structure, so the package you define in your .proto file will have no effect on the generated code. However, you should still declare package to avoid name collisions in the Protocol Buffers name space as well as in non-Python languages.

[deannagarcia]

Closing this since the similar issue is fixed: googleapis/python-api-core#372

[mcepl]

Yes, thank you.