Fix flake8-bugbear warning

B904 Within an `except` clause, raise exceptions with `raise ... from err`
     or `raise ... from None` to distinguish them from errors in exception
     handling

Author: DimitriPapadopoulos

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/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/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
 

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):