Sync from Piper @443569271

PROTOBUF_SYNC_PIPER

CHANGES.txt

@@ -1,3 +1,8 @@
+Unreleased Changes (C++/Java/Python/PHP/Objective-C/C#/Ruby/JavaScript)
+
+  Compiler
+  * Require package names to be less than 512 bytes in length
+
 2022-04-05 version 3.20.1 (C++/Java/Python/PHP/Objective-C/C#/Ruby/JavaScript)
 
   PHP

protobuf_deps.bzl

@@ -88,10 +88,10 @@ def protobuf_deps():
         http_archive(
             name = "rules_pkg",
             urls = [
-                "https://mirror.bazel.build/github.com/bazelbuild/rules_pkg/releases/download/0.5.1/rules_pkg-0.5.1.tar.gz",
+                "https://mirror.bazel.build/github.com/bazelbuild/rules_pkg/releases/download/0.7.0/rules_pkg-0.7.0.tar.gz",
-                "https://github.com/bazelbuild/rules_pkg/releases/download/0.5.1/rules_pkg-0.5.1.tar.gz",
+                "https://github.com/bazelbuild/rules_pkg/releases/download/0.7.0/rules_pkg-0.7.0.tar.gz",
             ],
-            sha256 = "a89e203d3cf264e564fcb96b6e06dd70bc0557356eb48400ce4b5d97c2c3720d",
+            sha256 = "8a298e832762eda1830597d64fe7db58178aa84cd5926d76d5b744d6558941c2",
         )
 
     if not native.existing_rule("io_bazel_rules_kotlin"):

python/google/protobuf/internal/api_implementation.py

@@ -59,11 +59,26 @@ except ImportError:
   pass  # Unspecified by compiler flags.
 
 
+def _CanImport(mod_name):
+  try:
+    mod = importlib.import_module(mod_name)
+    # Work around a known issue in the classic bootstrap .par import hook.
+    if not mod:
+      raise ImportError(mod_name + ' import succeeded but was None')
+    return True
+  except ImportError:
+    return False
 
 
 if _implementation_type is None:
+  if _CanImport('google._upb._message'):
+    _implementation_type = 'upb'
+  elif _CanImport('google.protobuf.pyext._message'):
+    _implementation_type = 'cpp'
+  else:
     _implementation_type = 'python'
 
+
 # This environment variable can be used to switch to a certain implementation
 # of the Python API, overriding the compile-time constants in the
 # _api_implementation module. Right now only 'python', 'cpp' and 'upb' are
@@ -98,7 +113,7 @@ if _implementation_type == 'cpp':
 if _implementation_type == 'upb':
   try:
     # pylint: disable=g-import-not-at-top
-    from google.protobuf.pyext import _upb_message as _message
+    from google._upb import _message
     _c_module = _message
     del _message
   except ImportError: