Drop support for python 3.6

.github/workflows/bionic-test.yml

@@ -20,10 +20,8 @@ jobs:
       # version.)
       fail-fast: false
       matrix:
-        python-version: [3.6, 3.7, 3.8]
+        python-version: [3.7, 3.8]
         include:
-          - python-version: 3.6
-            shard-id: 0
           - python-version: 3.7
             shard-id: 1
           - python-version: 3.8

bionic/code_hasher.py

@@ -37,9 +37,6 @@
 
 
 PREFIX_SEPARATOR = b"$"
-# This is gross but types.MethodWrapperType was introduced in Python 3.7
-# and does not exist in 3.6 which Bionic supports.
-METHOD_WRAPPER_TYPE = type("".__str__)
 
 
 class CodeHasher:
@@ -290,7 +287,9 @@ def _update_hash(self, hash_accumulator, obj, code_context):
                 obj_bytes=self._check_and_hash(builtin_name, code_context),
             )
 
-        elif inspect.ismethoddescriptor(obj) or isinstance(obj, METHOD_WRAPPER_TYPE):
+        elif inspect.ismethoddescriptor(obj) or isinstance(
+            obj, types.MethodWrapperType
+        ):
             if inspect.ismethoddescriptor(obj):
                 type_prefix = TypePrefix.METHOD_DESCRIPTOR
             else:

docs/get-started.rst

@@ -39,7 +39,7 @@ performance for some workloads.  LibYAML is also available via Homebrew:
 
     brew install libyaml
 
-Bionic supports Python 3.6 and above.
+Bionic supports Python 3.7 and above.
 
 .. _extra-packages:
 

setup.py

@@ -43,7 +43,7 @@
     include_package_data=True,
     install_requires=requirements,
     extras_require=extras_require,
-    python_requires=">=3.6",
+    python_requires=">=3.7",
     zip_safe=False,
     keywords="bionic",
     classifiers=[
@@ -52,6 +52,6 @@
         "Natural Language :: English",
         "License :: OSI Approved :: Apache Software License",
         "Programming Language :: Python :: 3",
-        "Programming Language :: Python :: 3.6",
+        "Programming Language :: Python :: 3.7",
     ],
 )

tests/test_flow/test_persistence_compatibility.py

@@ -1,6 +1,5 @@
 import pytest
 import shutil
-import sys
 
 from .generate_test_compatibility_cache import Harness, CACHE_TEST_DIR
 
@@ -26,15 +25,7 @@ def older_serialized_cache_harness(make_counter, tmp_path):
 # To renegerate cache, run the following command from bionic/ dir
 #   `python -m tests.test_flow.generate_test_compatibility_cache`
 def test_caching_compatibility(older_serialized_cache_harness):
-    # The auto-versioned flow generates different bytecode hashes on Python 3.6
-    # compared to 3.7 and 3.8 This is because Python 3.7 added new
-    # bytecode instructions like LOAD_METHOD and uses them widely.
-    # We skip the auto-versioned flow for Python 3.6 and only test it on
-    # Python 3.7+.
-    if sys.version_info < (3, 7):
-        flows = [older_serialized_cache_harness.manual_flow]
-    else:
-        flows = older_serialized_cache_harness.flows
+    flows = older_serialized_cache_harness.flows
 
     for flow in flows:
         assert (