Fix B904 (raise exceptions with `raise ... from ...`)

pyproject.toml

@@ -162,8 +162,6 @@ ignore = [
     "ARG002",  #  unused method argument
     "ARG003",  #  unused class method argument
     "ARG005",  #  unused lambda argument
-    # flake8-bugbear opinionated (disabled by default in flake8)
-    "B904",  # within an except clause, raise exceptions with `raise ... from ...`
     # flake8-blind-except
     "BLE001",  # do not catch blind exception
     # mccabe

sphinx/domains/cpp.py

@@ -6646,7 +6646,7 @@ class DefinitionParser(BaseParser):
                 elif outer == 'function':
                     desc = "If the function has no return type"
                 else:
-                    raise AssertionError
+                    raise AssertionError from exUntyped
                 prevErrors.append((exUntyped, desc))
                 self.pos = startPos
                 try:
@@ -6659,7 +6659,7 @@ class DefinitionParser(BaseParser):
                     elif outer == 'function':
                         desc = "If the function has a return type"
                     else:
-                        raise AssertionError
+                        raise AssertionError from exUntyped
                     prevErrors.append((exTyped, desc))
                     # Retain the else branch for easier debugging.
                     # TODO: it would be nice to save the previous stacktrace
@@ -6671,7 +6671,7 @@ class DefinitionParser(BaseParser):
                         elif outer == 'function':
                             header = "Error when parsing function declaration."
                         else:
-                            raise AssertionError
+                            raise AssertionError from exUntyped
                         raise self._make_multi_error(prevErrors, header) from exTyped
                     else:  # NoQA: RET506
                         # For testing purposes.
@@ -6733,7 +6733,7 @@ class DefinitionParser(BaseParser):
             return ASTTemplateParamConstrainedTypeWithInit(type, typeInit)
         except DefinitionError as eType:
             if eExpr is None:
-                raise eType
+                raise
             errs = []
             errs.append((eExpr, "If default template argument is an expression"))
             errs.append((eType, "If default template argument is a type"))
@@ -6877,7 +6877,7 @@ class DefinitionParser(BaseParser):
                     (eType, "If unconstrained type parameter or template type parameter"))
                 errs.append(
                     (eNonType, "If constrained type parameter or non-type parameter"))
-                raise self._make_multi_error(errs, header)
+                raise self._make_multi_error(errs, header) from None
 
     def _parse_template_parameter_list(self) -> ASTTemplateParams:
         # only: '<' parameter-list '>'

sphinx/ext/autosummary/__init__.py

@@ -286,7 +286,7 @@ class Autosummary(SphinxDirective):
                     else:
                         errors = exc.exceptions + [exc2]
 
-                    raise ImportExceptionGroup(exc.args[0], errors)
+                    raise ImportExceptionGroup(exc.args[0], errors) from None
 
     def create_documenter(self, app: Sphinx, obj: Any,
                           parent: Any, full_name: str) -> Documenter:
@@ -695,7 +695,7 @@ def _import_by_name(name: str, grouped_exception: bool = True) -> tuple[Any, Any
     except (ValueError, ImportError, AttributeError, KeyError) as exc:
         errors.append(exc)
         if grouped_exception:
-            raise ImportExceptionGroup('', errors)
+            raise ImportExceptionGroup('', errors) from None
         else:
             raise ImportError(*exc.args) from exc
 

tests/test_build_epub.py

@@ -385,7 +385,7 @@ def test_run_epubcheck(app):
         except CalledProcessError as exc:
             print(exc.stdout.decode('utf-8'))
             print(exc.stderr.decode('utf-8'))
-            raise AssertionError('epubcheck exited with return code %s' % exc.returncode)
+            raise AssertionError(f'epubcheck exited with return code {exc.returncode}') from exc
 
 
 def test_xml_name_pattern_check():

tests/test_build_gettext.py

@@ -74,7 +74,7 @@ def test_msgfmt(app):
         except CalledProcessError as exc:
             print(exc.stdout)
             print(exc.stderr)
-            raise AssertionError('msginit exited with return code %s' % exc.returncode)
+            raise AssertionError(f'msginit exited with return code {exc.returncode}') from exc
 
         assert (app.outdir / 'en_US.po').is_file(), 'msginit failed'
         try:
@@ -86,7 +86,7 @@ def test_msgfmt(app):
         except CalledProcessError as exc:
             print(exc.stdout)
             print(exc.stderr)
-            raise AssertionError('msgfmt exited with return code %s' % exc.returncode)
+            raise AssertionError(f'msgfmt exited with return code {exc.returncode}') from exc
 
         mo = app.outdir / 'en' / 'LC_MESSAGES' / 'test_root.mo'
         assert mo.is_file(), 'msgfmt failed'

tests/test_build_latex.py

@@ -73,7 +73,7 @@ def compile_latex_document(app, filename='python.tex', docclass='manual'):
         print(exc.stdout.decode('utf8'))
         print(exc.stderr.decode('utf8'))
         raise AssertionError(f'{app.config.latex_engine} exited with '
-                             f'return code {exc.returncode}')
+                             f'return code {exc.returncode}') from exc
 
 
 def skip_if_requested(testfunc):

tests/test_build_texinfo.py

@@ -56,7 +56,7 @@ def test_texinfo(app, status, warning):
     except CalledProcessError as exc:
         print(exc.stdout)
         print(exc.stderr)
-        raise AssertionError('makeinfo exited with return code %s' % exc.retcode)
+        raise AssertionError(f'makeinfo exited with return code {exc.retcode}') from exc
 
 
 @pytest.mark.sphinx('texinfo', testroot='markup-rubric')

utils/babel_runner.py

@@ -231,7 +231,7 @@ if __name__ == '__main__':
         action = sys.argv[1].lower()
     except IndexError:
         print(__doc__, file=sys.stderr)
-        raise SystemExit(2)
+        raise SystemExit(2) from None
 
     os.chdir(ROOT)
     if action == "extract":