Fix flake8-bugbear warnings

pkg_resources/__init__.py

@@ -407,7 +407,7 @@ def get_provider(moduleOrReq):
     return _find_adapter(_provider_factories, loader)(module)
 
 
-def _macos_vers(_cache=[]):
+def _macos_vers(_cache=None):
     if not _cache:
         version = platform.mac_ver()[0]
         # fallback for MacPorts
@@ -419,7 +419,7 @@ def _macos_vers(_cache=[]):
                     if 'ProductVersion' in plist_content:
                         version = plist_content['ProductVersion']
 
-        _cache.append(version.split('.'))
+        _cache = [version.split('.')]
     return _cache[0]
 
 
@@ -2422,7 +2422,8 @@ def _cygwin_patch(filename):  # pragma: nocover
     return os.path.abspath(filename) if sys.platform == 'cygwin' else filename
 
 
-def _normalize_cached(filename, _cache={}):
+def _normalize_cached(filename, _cache=None):
+    _cache = _cache or {}
     try:
         return _cache[filename]
     except KeyError:

setuptools/build_meta.py

@@ -117,11 +117,11 @@ def _file_with_extension(directory, extension):
     matching = (f for f in os.listdir(directory) if f.endswith(extension))
     try:
         (file,) = matching
-    except ValueError:
+    except ValueError as e:
         raise ValueError(
             'No distribution was found. Ensure that `setup.py` '
             'is not empty and that it calls `setup()`.'
-        )
+        ) from e
     return file
 
 

setuptools/command/build_ext.py

@@ -157,7 +157,7 @@ def get_ext_filename(self, fullname):
 
         if fullname in self.ext_map:
             ext = self.ext_map[fullname]
-            use_abi3 = getattr(ext, 'py_limited_api') and get_abi3_suffix()
+            use_abi3 = ext.py_limited_api and get_abi3_suffix()
             if use_abi3:
                 filename = filename[: -len(so_ext)]
                 so_ext = get_abi3_suffix()

setuptools/command/build_py.py

@@ -288,7 +288,7 @@ def exclude_data_files(self, package, src_dir, files):
         return list(unique_everseen(keepers))
 
     @staticmethod
-    def _get_platform_patterns(spec, package, src_dir, extra_patterns=[]):
+    def _get_platform_patterns(spec, package, src_dir, extra_patterns=()):
         """
         yield platform-specific path patterns (suitable for glob
         or fn_match) from a glob-based spec (such as

setuptools/command/egg_info.py

@@ -384,10 +384,10 @@ def process_template_line(self, line):
 
         try:
             process_action = action_map[action]
-        except KeyError:
+        except KeyError as e:
             raise DistutilsInternalError(
                 "this cannot happen: invalid action '{action!s}'".format(action=action),
-            )
+            ) from e
 
         # OK, now we know that the action is valid and we have the
         # right number of words on the line for that action -- so we

setuptools/command/sdist.py

@@ -106,7 +106,7 @@ class NoValue:
             yield
         finally:
             if orig_val is not NoValue:
-                setattr(os, 'link', orig_val)
+                os.link = orig_val
 
     def add_defaults(self):
         super().add_defaults()

setuptools/command/test.py

@@ -132,7 +132,7 @@ def with_project_on_sys_path(self, func):
             func()
 
     @contextlib.contextmanager
-    def project_on_sys_path(self, include_dists=[]):
+    def project_on_sys_path(self, include_dists=()):
         self.run_command('egg_info')
 
         # Build extensions in-place

setuptools/config/_validate_pyproject/error_reporting.py

@@ -24,7 +24,7 @@
     "must not be there",
 )
 
-_NEED_DETAILS = {"anyOf", "oneOf", "anyOf", "contains", "propertyNames", "not", "items"}
+_NEED_DETAILS = {"anyOf", "oneOf", "contains", "propertyNames", "not", "items"}
 
 _CAMEL_CASE_SPLITTER = re.compile(r"\W+|([A-Z][^A-Z\W]*)")
 _IDENTIFIER = re.compile(r"^[\w_]+$", re.I)

setuptools/config/setupcfg.py

@@ -283,8 +283,8 @@ def __setitem__(self, option_name, value):
 
         try:
             current_value = getattr(target_obj, option_name)
-        except AttributeError:
-            raise KeyError(option_name)
+        except AttributeError as e:
+            raise KeyError(option_name) from e
 
         if current_value:
             # Already inhabited. Skipping.
@@ -582,11 +582,11 @@ def _parse_version(self, value):
             # accidentally include newlines and other unintended content
             try:
                 Version(version)
-            except InvalidVersion:
+            except InvalidVersion as e:
                 raise OptionError(
                     f'Version loaded from {value} does not '
                     f'comply with PEP 440: {version}'
-                )
+                ) from e
 
             return version
 

setuptools/monkey.py

@@ -130,7 +130,7 @@ def patch_func(replacement, target_mod, func_name):
 
 
 def get_unpatched_function(candidate):
-    return getattr(candidate, 'unpatched')
+    return getattr(candidate, 'unpatched', None)
 
 
 def patch_for_msvc_specialized_compiler():

setuptools/tests/config/test_setupcfg.py

@@ -957,17 +957,13 @@ class TestExternalSetters:
     # pbr or something else setting these values.
     def _fake_distribution_init(self, dist, attrs):
         saved_dist_init(dist, attrs)
-        # see self._DISTUTUILS_UNSUPPORTED_METADATA
-        setattr(dist.metadata, 'long_description_content_type', 'text/something')
+        # see self._DISTUTILS_UNSUPPORTED_METADATA
+        dist.metadata.long_description_content_type = 'text/something'
         # Test overwrite setup() args
-        setattr(
-            dist.metadata,
-            'project_urls',
-            {
-                'Link One': 'https://example.com/one/',
-                'Link Two': 'https://example.com/two/',
-            },
-        )
+        dist.metadata.project_urls = {
+            'Link One': 'https://example.com/one/',
+            'Link Two': 'https://example.com/two/',
+        }
         return None
 
     @patch.object(_Distribution, '__init__', autospec=True)

setuptools/tests/test_build_meta.py

@@ -30,9 +30,9 @@
 
 
 class BuildBackendBase:
-    def __init__(self, cwd='.', env={}, backend_name='setuptools.build_meta'):
+    def __init__(self, cwd='.', env=None, backend_name='setuptools.build_meta'):
         self.cwd = cwd
-        self.env = env
+        self.env = env or {}
         self.backend_name = backend_name
 
 

setuptools/tests/test_easy_install.py

@@ -1195,7 +1195,7 @@ def create_setup_requires_package(
     version='0.1',
     make_package=make_trivial_sdist,
     setup_py_template=None,
-    setup_attrs={},
+    setup_attrs=None,
     use_setup_cfg=(),
 ):
     """Creates a source tree under path for a trivial test package that has a
@@ -1213,7 +1213,8 @@ def create_setup_requires_package(
         'setup_requires': ['%s==%s' % (distname, version)],
         'dependency_links': [os.path.abspath(path)],
     }
-    test_setup_attrs.update(setup_attrs)
+    if setup_attrs:
+        test_setup_attrs.update(setup_attrs)
 
     test_pkg = os.path.join(path, 'test_pkg')
     os.mkdir(test_pkg)

setuptools/tests/test_sdist.py

@@ -658,7 +658,7 @@ def test_sdist_with_latin1_encoded_filename(self):
         else:
             # The Latin-1 filename should have been skipped
             filename = filename.decode('latin-1')
-            filename not in cmd.filelist.files
+            assert filename not in cmd.filelist.files
 
     _EXAMPLE_DIRECTIVES = {
         "setup.cfg - long_description and version": """

setuptools/tests/test_setuptools.py

@@ -61,13 +61,13 @@ def f1():
         assert dep.extract_constant(fc, 'q', -1) is None
 
         # constant assigned
-        dep.extract_constant(fc, 'x', -1) == "test"
+        assert dep.extract_constant(fc, 'x', -1) == "test"
 
         # expression assigned
-        dep.extract_constant(fc, 'y', -1) == -1
+        assert dep.extract_constant(fc, 'y', -1) == -1
 
         # recognized name, not assigned
-        dep.extract_constant(fc, 'z', -1) is None
+        assert dep.extract_constant(fc, 'z', -1) is None
 
     def testFindModule(self):
         with pytest.raises(ImportError):

tools/build_launchers.py

@@ -118,8 +118,8 @@ def get_msbuild():
     ]
     try:
         return subprocess.check_output(cmd, encoding='utf-8', text=True).strip()
-    except subprocess.CalledProcessError:
-        raise SystemExit("Unable to find MSBuild; check Visual Studio install")
+    except subprocess.CalledProcessError as e:
+        raise SystemExit("Unable to find MSBuild; check Visual Studio install") from e
 
 
 def do_build(arena, platform, target):