Add warn-unreachable to strict mode

[johng]

This is useful check for dead code analysis

Closes #11223

This adds a useful check to the default list of strict arguments

[github-actions]

Diff from mypy_primer, showing the effect of this PR on open source code:

websockets (https://github.com/aaugustin/websockets)
+ src/websockets/legacy/protocol.py:320: error: Statement is unreachable  [unreachable]
+ src/websockets/legacy/protocol.py:1076: error: Statement is unreachable  [unreachable]
+ src/websockets/legacy/server.py:365: error: Statement is unreachable  [unreachable]
+ src/websockets/legacy/server.py:590: error: Statement is unreachable  [unreachable]

psycopg (https://github.com/psycopg/psycopg)
+ psycopg/psycopg/pq/pq_ctypes.py:133: error: Statement is unreachable  [unreachable]
+ psycopg/psycopg/pq/pq_ctypes.py:861: error: Statement is unreachable  [unreachable]
+ psycopg/psycopg/pq/pq_ctypes.py:1039: error: Statement is unreachable  [unreachable]
+ psycopg/psycopg/pq/pq_ctypes.py:1071: error: Statement is unreachable  [unreachable]
+ psycopg/psycopg/pq/__init__.py:96: error: Statement is unreachable  [unreachable]
+ psycopg/psycopg/_conninfo_attempts_async.py:97: error: Statement is unreachable  [unreachable]
+ psycopg/psycopg/sql.py:89: error: Statement is unreachable  [unreachable]
+ psycopg/psycopg/sql.py:97: error: Statement is unreachable  [unreachable]
+ psycopg/psycopg/sql.py:151: error: Statement is unreachable  [unreachable]
+ psycopg/psycopg/_queries.py:362: error: Statement is unreachable  [unreachable]
+ psycopg/psycopg/_queries.py:409: error: Statement is unreachable  [unreachable]
+ psycopg/psycopg/connection_async.py:40: error: Statement is unreachable  [unreachable]
+ psycopg/psycopg/connection_async.py:57: error: Statement is unreachable  [unreachable]
+ psycopg/psycopg/connection_async.py:307: error: Statement is unreachable  [unreachable]
+ psycopg/psycopg/connection_async.py:430: error: Statement is unreachable  [unreachable]
+ psycopg/psycopg/connection_async.py:441: error: Statement is unreachable  [unreachable]
+ psycopg/psycopg/connection_async.py:452: error: Statement is unreachable  [unreachable]
+ psycopg/psycopg/connection_async.py:463: error: Statement is unreachable  [unreachable]
+ psycopg/psycopg/types/uuid.py:42: error: Statement is unreachable  [unreachable]
+ psycopg/psycopg/types/net.py:48: error: Statement is unreachable  [unreachable]
+ psycopg/psycopg/types/net.py:182: error: Statement is unreachable  [unreachable]
+ psycopg/psycopg/types/multirange.py:340: error: Statement is unreachable  [unreachable]
+ tests/test_psycopg_dbapi20.py:144: error: Statement is unreachable  [unreachable]
+ tests/test_cursor_async.py:42: error: Statement is unreachable  [unreachable]
+ tests/test_cursor.py:43: error: Statement is unreachable  [unreachable]
+ tests/pq/test_pgconn.py:42: error: Statement is unreachable  [unreachable]
+ tests/test_transaction_async.py:138: error: Statement is unreachable  [unreachable]
+ tests/test_transaction_async.py:504: error: Statement is unreachable  [unreachable]
+ tests/test_transaction_async.py:505: error: Statement is unreachable  [unreachable]
+ tests/test_transaction_async.py:552: error: Statement is unreachable  [unreachable]
+ tests/test_transaction_async.py:576: error: Statement is unreachable  [unreachable]
+ tests/test_transaction_async.py:579: error: Statement is unreachable  [unreachable]
+ tests/test_transaction_async.py:594: error: Statement is unreachable  [unreachable]
+ tests/test_transaction_async.py:609: error: Statement is unreachable  [unreachable]
+ tests/test_transaction_async.py:614: error: Statement is unreachable  [unreachable]
+ tests/test_transaction.py:138: error: Statement is unreachable  [unreachable]
+ tests/test_transaction.py:497: error: Statement is unreachable  [unreachable]
+ tests/test_transaction.py:498: error: Statement is unreachable  [unreachable]
+ tests/test_transaction.py:545: error: Statement is unreachable  [unreachable]
+ tests/test_transaction.py:569: error: Statement is unreachable  [unreachable]
+ tests/test_transaction.py:572: error: Statement is unreachable  [unreachable]
+ tests/test_transaction.py:587: error: Statement is unreachable  [unreachable]
+ tests/test_transaction.py:602: error: Statement is unreachable  [unreachable]
+ tests/test_transaction.py:607: error: Statement is unreachable  [unreachable]
+ tests/test_pipeline_async.py:44: error: Statement is unreachable  [unreachable]
+ tests/test_pipeline_async.py:45: error: Statement is unreachable  [unreachable]
+ tests/test_pipeline_async.py:464: error: Statement is unreachable  [unreachable]
+ tests/test_pipeline_async.py:467: error: Statement is unreachable  [unreachable]
+ tests/test_pipeline.py:47: error: Statement is unreachable  [unreachable]
+ tests/test_pipeline.py:48: error: Statement is unreachable  [unreachable]
+ tests/test_pipeline.py:465: error: Statement is unreachable  [unreachable]
+ tests/test_pipeline.py:468: error: Statement is unreachable  [unreachable]
+ tests/test_cursor_server_async.py:104: error: Statement is unreachable  [unreachable]
+ tests/test_cursor_server.py:101: error: Statement is unreachable  [unreachable]
+ tests/test_cursor_raw_async.py:47: error: Statement is unreachable  [unreachable]
+ tests/test_cursor_raw.py:50: error: Statement is unreachable  [unreachable]
+ tests/test_copy_async.py:688: error: Statement is unreachable  [unreachable]
+ tests/test_copy.py:674: error: Statement is unreachable  [unreachable]
+ tests/test_connection_async.py:363: error: Statement is unreachable  [unreachable]
+ tests/test_connection_async.py:389: error: Subclass of "str" and "bool" cannot exist: "bool" is final  [unreachable]
+ tests/test_connection_async.py:390: error: Statement is unreachable  [unreachable]
+ tests/test_connection_async.py:455: error: Statement is unreachable  [unreachable]
+ tests/test_connection.py:366: error: Statement is unreachable  [unreachable]
+ tests/test_connection.py:392: error: Subclass of "str" and "bool" cannot exist: "bool" is final  [unreachable]
+ tests/test_connection.py:393: error: Statement is unreachable  [unreachable]
+ tests/test_connection.py:458: error: Statement is unreachable  [unreachable]
+ tests/pool/test_sched_async.py:153: error: Statement is unreachable  [unreachable]
+ psycopg_pool/psycopg_pool/pool_async.py:107: error: Statement is unreachable  [unreachable]
+ psycopg_pool/psycopg_pool/pool_async.py:126: error: Statement is unreachable  [unreachable]
+ psycopg_pool/psycopg_pool/pool_async.py:583: error: Statement is unreachable  [unreachable]
+ psycopg_pool/psycopg_pool/pool_async.py:602: error: Statement is unreachable  [unreachable]
+ psycopg_pool/psycopg_pool/pool_async.py:782: error: Statement is unreachable  [unreachable]
+ psycopg_pool/psycopg_pool/pool.py:731: error: Statement is unreachable  [unreachable]
+ tests/crdb/test_connection_async.py:26: error: Statement is unreachable  [unreachable]
+ tests/test_cursor_common_async.py:494: error: Statement is unreachable  [unreachable]
+ tests/test_cursor_common.py:490: error: Statement is unreachable  [unreachable]
+ tests/test_cursor_client_async.py:56: error: Statement is unreachable  [unreachable]
+ tests/test_cursor_client.py:57: error: Statement is unreachable  [unreachable]
+ tests/types/test_enum.py:86: error: Statement is unreachable  [unreachable]
+ tests/pool/test_pool_common_async.py:71: error: Statement is unreachable  [unreachable]

bidict (https://github.com/jab/bidict)
+ bidict/_base.py: note: In member "__or__" of class "BidictBase":
+ bidict/_base.py:501:13: error: Statement is unreachable  [unreachable]
+ bidict/_base.py: note: In member "__ror__" of class "BidictBase":
+ bidict/_base.py:509:13: error: Statement is unreachable  [unreachable]

boostedblob (https://github.com/hauntsaninja/boostedblob)
+ boostedblob/azure_auth.py:107: error: Statement is unreachable  [unreachable]

pylint (https://github.com/pycqa/pylint)
+ pylint/lint/expand_modules.py:113: error: Statement is unreachable  [unreachable]
+ pylint/pyreverse/dot_printer.py:159: error: Statement is unreachable  [unreachable]
+ pylint/lint/message_state_handler.py:358: error: Right operand of "and" is never evaluated  [unreachable]
+ pylint/lint/message_state_handler.py:359: error: Statement is unreachable  [unreachable]
+ pylint/checkers/base_checker.py:174: error: Right operand of "and" is never evaluated  [unreachable]
+ pylint/checkers/base_checker.py:175: error: Statement is unreachable  [unreachable]
+ pylint/checkers/base_checker.py:196: error: Statement is unreachable  [unreachable]
+ pylint/checkers/symilar.py:832: error: Statement is unreachable  [unreachable]
+ pylint/lint/run.py:197: error: Statement is unreachable  [unreachable]
+ pylint/lint/run.py:206: error: Statement is unreachable  [unreachable]
+ pylint/checkers/logging.py:356: error: Subclass of "str" and "int" cannot exist: would have incompatible method signatures  [unreachable]
+ pylint/checkers/imports.py:594: error: Right operand of "and" is never evaluated  [unreachable]
+ pylint/checkers/imports.py:603: error: Statement is unreachable  [unreachable]
+ pylint/checkers/imports.py:631: error: Statement is unreachable  [unreachable]
+ pylint/checkers/imports.py:660: error: Statement is unreachable  [unreachable]
+ pylint/checkers/imports.py:707: error: Statement is unreachable  [unreachable]

sphinx (https://github.com/sphinx-doc/sphinx)
+ sphinx/util/requests.py: note: In member "request" of class "_Session":
+ sphinx/util/requests.py:72:13: error: Statement is unreachable  [unreachable]
+ sphinx/pycode/parser.py: note: In member "visit_Expr" of class "VariableCommentPicker":
+ sphinx/pycode/parser.py:435:25: error: Statement is unreachable  [unreachable]
+ sphinx/util/typing.py: note: In function "restify":
+ sphinx/util/typing.py:304:13: error: Statement is unreachable  [unreachable]
+ sphinx/util/typing.py:328:27: error: Subclass of "type" and "<typing special form>" cannot exist: "_SpecialForm" is final  [unreachable]
+ sphinx/util/typing.py:331:17: error: Statement is unreachable  [unreachable]
+ sphinx/util/typing.py: note: In function "stringify_annotation":
+ sphinx/util/typing.py:568:13: error: Statement is unreachable  [unreachable]
+ sphinx/util/nodes.py: note: In function "apply_source_workaround":
+ sphinx/util/nodes.py:151:9: error: Statement is unreachable  [unreachable]
+ sphinx/util/nodes.py:158:9: error: Statement is unreachable  [unreachable]
+ sphinx/util/nodes.py:177:9: error: Statement is unreachable  [unreachable]
+ sphinx/util/nodes.py:186:9: error: Statement is unreachable  [unreachable]
+ sphinx/util/nodes.py: note: In function "_deepcopy":
+ sphinx/util/nodes.py:741:17: error: Statement is unreachable  [unreachable]
+ sphinx/util/nodes.py:743:17: error: Statement is unreachable  [unreachable]
+ sphinx/util/inspect.py: note: In function "stringify_signature":
+ sphinx/util/inspect.py:774:13: error: Statement is unreachable  [unreachable]
+ sphinx/domains/python/_annotations.py: note: In function "_parse_arglist":
+ sphinx/domains/python/_annotations.py:438:13: error: Statement is unreachable  [unreachable]
+ sphinx/directives/__init__.py: note: In function "optional_int":
+ sphinx/directives/__init__.py:34:9: error: Statement is unreachable  [unreachable]
+ sphinx/directives/__init__.py:336:13: error: Statement is unreachable  [unreachable]
+ sphinx/domains/python/_object.py: note: In member "handle_signature" of class "PyObject":
+ sphinx/domains/python/_object.py:263:21: error: Subclass of "list[Node]" and "str" cannot exist: would have incompatible method signatures  [unreachable]
+ sphinx/highlighting.py: note: In member "highlight_block" of class "PygmentsBridge":
+ sphinx/highlighting.py:187:13: error: Statement is unreachable  [unreachable]
+ sphinx/config.py: note: In member "add" of class "Config":
+ sphinx/config.py:462:13: error: Statement is unreachable  [unreachable]
+ sphinx/config.py: note: In member "filter" of class "Config":
+ sphinx/config.py:469:23: error: Subclass of "AbstractSet[Literal['', 'env', 'epub', 'gettext', 'html', 'applehelp', 'devhelp']]" and "str" cannot exist: would have incompatible method signatures  [unreachable]
+ sphinx/config.py:470:13: error: Statement is unreachable  [unreachable]
+ sphinx/config.py: note: In member "__getstate__" of class "Config":
+ sphinx/config.py:484:16: error: Right operand of "and" is never evaluated  [unreachable]
+ sphinx/config.py:484:57: error: Subclass of "_Opt" and "tuple[Any, ...]" cannot exist: would have incompatible method signatures  [unreachable]
+ sphinx/config.py:486:17: error: Statement is unreachable  [unreachable]
+ sphinx/util/rst.py:72:13: error: Statement is unreachable  [unreachable]
+ sphinx/util/display.py:10:5: error: Statement is unreachable  [unreachable]
+ sphinx/domains/std/__init__.py: note: In member "process_doc" of class "StandardDomain":
+ sphinx/domains/std/__init__.py:795:17: error: Statement is unreachable  [unreachable]
+ sphinx/theming.py: note: In function "_validate_theme_toml":
+ sphinx/theming.py:346:9: error: Statement is unreachable  [unreachable]
+ sphinx/theming.py:350:9: error: Statement is unreachable  [unreachable]
+ sphinx/theming.py:358:13: error: Statement is unreachable  [unreachable]
+ sphinx/theming.py: note: In function "_convert_theme_toml":
+ sphinx/theming.py:375:9: error: Statement is unreachable  [unreachable]
+ sphinx/transforms/__init__.py: note: In member "apply_transforms" of class "SphinxTransformer":
+ sphinx/transforms/__init__.py:97:13: error: Statement is unreachable  [unreachable]
+ sphinx/transforms/__init__.py: note: In function "_reorder_index_target_nodes":
+ sphinx/transforms/__init__.py:504:9: error: Statement is unreachable  [unreachable]
+ sphinx/ext/autodoc/importer.py: note: In function "import_object":
+ sphinx/ext/autodoc/importer.py:200:9: error: Statement is unreachable  [unreachable]
+ sphinx/ext/autodoc/__init__.py: note: In member "_find_signature" of class "DocstringSignatureMixin":
+ sphinx/ext/autodoc/__init__.py:1252:21: error: Statement is unreachable  [unreachable]
+ sphinx/ext/autodoc/__init__.py: note: In function "_get_signature":
+ sphinx/ext/autodoc/__init__.py:1539:38: error: Subclass of "str" and "MethodType" cannot exist: "MethodType" is final  [unreachable]
+ sphinx/ext/autodoc/__init__.py:1539:66: error: Subclass of "str" and "FunctionType" cannot exist: "FunctionType" is final  [unreachable]
+ sphinx/ext/autodoc/__init__.py:1541:13: error: Statement is unreachable  [unreachable]
+ sphinx/ext/autodoc/__init__.py: note: In member "format_signature" of class "MethodDocumenter":
+ sphinx/ext/autodoc/__init__.py:2257:25: error: Statement is unreachable  [unreachable]
+ sphinx/ext/autodoc/__init__.py: note: In member "import_object" of class "PropertyDocumenter":
+ sphinx/ext/autodoc/__init__.py:2766:17: error: Statement is unreachable  [unreachable]
+ sphinx/environment/adapters/toctree.py: note: In function "_toctree_url_entry":
+ sphinx/environment/adapters/toctree.py:368:9: error: Statement is unreachable  [unreachable]
+ sphinx/domains/cpp/_ast.py: note: In member "describe_signature" of class "ASTNestedName":
+ sphinx/domains/cpp/_ast.py:255:17: error: Statement is unreachable  [unreachable]
+ sphinx/domains/cpp/_ast.py:260:21: error: Statement is unreachable  [unreachable]
+ sphinx/domains/cpp/_ast.py:265:21: error: Statement is unreachable  [unreachable]
+ sphinx/domains/cpp/_ast.py: note: In member "get_ptr_suffix_id" of class "ASTDeclaratorMemPtr":
+ sphinx/domains/cpp/_ast.py:2940:9: error: Statement is unreachable  [unreachable]
+ sphinx/domains/cpp/_ast.py: note: In member "get_ptr_suffix_id" of class "ASTDeclaratorParen":
+ sphinx/domains/cpp/_ast.py:3033:13: error: Statement is unreachable  [unreachable]
+ sphinx/domains/c/_ast.py: note: In member "describe_signature" of class "ASTNestedName":
+ sphinx/domains/c/_ast.py:139:17: error: Statement is unreachable  [unreachable]
+ sphinx/domains/c/_ast.py:144:21: error: Statement is unreachable  [unreachable]
+ sphinx/domains/cpp/_parser.py: note: In member "_parse_type" of class "DefinitionParser":
+ sphinx/domains/cpp/_parser.py:1597:25: error: Statement is unreachable  [unreachable]
+ sphinx/domains/c/_parser.py: note: In member "_parse_initializer" of class "DefinitionParser":
+ sphinx/domains/c/_parser.py:832:13: error: Statement is unreachable  [unreachable]
+ sphinx/domains/c/_parser.py: note: In member "_parse_type" of class "DefinitionParser":
+ sphinx/domains/c/_parser.py:900:25: error: Statement is unreachable  [unreachable]
+ sphinx/domains/cpp/__init__.py: note: In member "add_target_and_index" of class "CPPObject":
+ sphinx/domains/cpp/__init__.py:227:13: error: Statement is unreachable  [unreachable]
+ sphinx/environment/__init__.py: note: In member "setup" of class "BuildEnvironment":
+ sphinx/environment/__init__.py:262:13: error: Statement is unreachable  [unreachable]
+ sphinx/registry.py: note: In member "preload_builder" of class "SphinxComponentRegistry":
+ sphinx/registry.py:150:13: error: Statement is unreachable  [unreachable]
+ sphinx/registry.py: note: In member "load_extension" of class "SphinxComponentRegistry":
+ sphinx/registry.py:476:17: error: Statement is unreachable  [unreachable]
+ sphinx/registry.py:478:17: error: Statement is unreachable  [unreachable]
+ sphinx/application.py: note: In member "create_builder" of class "Sphinx":
+ sphinx/application.py:362:13: error: Statement is unreachable  [unreachable]
+ sphinx/jinja2glue.py: note: In function "_tobool":
+ sphinx/jinja2glue.py:30:5: error: Statement is unreachable  [unreachable]
+ sphinx/jinja2glue.py: note: In function "_todim":
+ sphinx/jinja2glue.py:52:9: error: Statement is unreachable  [unreachable]
+ sphinx/builders/gettext.py: note: In member "add" of class "Catalog":
+ sphinx/builders/gettext.py:75:13: error: Statement is unreachable  [unreachable]
+ sphinx/builders/gettext.py: note: At top level:
+ sphinx/writers/latex.py: note: In function "visit_enumerated_list":
+ sphinx/writers/latex.py:1417:17: error: Statement is unreachable  [unreachable]
+ sphinx/builders/html/__init__.py: note: In member "add_sidebars" of class "StandaloneHTMLBuilder":
+ sphinx/builders/html/__init__.py:1030:32: error: Right operand of "and" is never evaluated  [unreachable]
+ sphinx/builders/html/__init__.py:1032:21: error: Statement is unreachable  [unreachable]
+ sphinx/testing/util.py: note: In member "__init__" of class "SphinxTestApp":
+ sphinx/testing/util.py:148:13: error: Statement is unreachable  [unreachable]
+ sphinx/testing/util.py:156:13: error: Statement is unreachable  [unreachable]
+ sphinx/ext/viewcode.py: note: In function "_get_full_modname":
+ sphinx/ext/viewcode.py:54:13: error: Statement is unreachable  [unreachable]
+ sphinx/ext/extlinks.py: note: In function "make_link_role":
+ sphinx/ext/extlinks.py:107:17: error: Statement is unreachable  [unreachable]
+ sphinx/ext/doctest.py: note: In member "get_line_number" of class "DocTestBuilder":
+ sphinx/ext/doctest.py:389:9: error: Statement is unreachable  [unreachable]
+ sphinx/ext/napoleon/docstring.py: note: In member "_get_min_indent" of class "GoogleDocstring":
+ sphinx/ext/napoleon/docstring.py:553:42: error: Right operand of "or" is never evaluated  [unreachable]

... (truncated 35 lines) ...

mypy (https://github.com/python/mypy)
+ mypy/nodes.py:189: error: Statement is unreachable  [unreachable]
+ mypy/nodes.py:189: note: See https://mypy.rtfd.io/en/stable/_refs.html#code-unreachable for more info
+ mypy/nodes.py:3249: error: Statement is unreachable  [unreachable]
+ mypy/nodes.py:4007: error: Statement is unreachable  [unreachable]
+ mypy/types.py:3307: error: Statement is unreachable  [unreachable]
+ mypy/types.py:3324: error: Statement is unreachable  [unreachable]
+ mypy/types.py:3366: error: Statement is unreachable  [unreachable]
+ mypy/server/mergecheck.py:32: error: Statement is unreachable  [unreachable]
+ mypy/server/astmerge.py:305: error: Statement is unreachable  [unreachable]
+ mypy/errors.py:1069: error: Statement is unreachable  [unreachable]
+ mypyc/ir/pprint.py:230: error: Statement is unreachable  [unreachable]
+ mypyc/test/test_cheader.py:36: error: Statement is unreachable  [unreachable]
+ mypy/constraints.py:130: error: Right operand of "and" is never evaluated  [unreachable]
+ mypy/constraints.py:133: error: Statement is unreachable  [unreachable]
+ mypy/constraints.py:514: error: Statement is unreachable  [unreachable]
+ mypy/messages.py:2133: error: Statement is unreachable  [unreachable]
+ mypy/messages.py:2137: error: Statement is unreachable  [unreachable]
+ mypy/checkmember.py:1104: error: Right operand of "and" is never evaluated  [unreachable]
+ mypy/checkmember.py:1107: error: Right operand of "and" is never evaluated  [unreachable]
+ mypy/checkmember.py:1150: error: Statement is unreachable  [unreachable]
+ mypy/checkmember.py:1409: error: Statement is unreachable  [unreachable]
+ mypy/semanal.py:3083: error: Statement is unreachable  [unreachable]
+ mypy/semanal.py:5661: error: Right operand of "and" is never evaluated  [unreachable]
+ mypy/semanal.py:5663: error: Statement is unreachable  [unreachable]
+ mypy/checkexpr.py:2570: error: Statement is unreachable  [unreachable]
+ mypy/checker.py:2716: error: Statement is unreachable  [unreachable]
+ mypy/checker.py:4271: error: Statement is unreachable  [unreachable]
+ mypy/server/deps.py:506: error: Statement is unreachable  [unreachable]
+ mypy/server/astdiff.py:238: error: Statement is unreachable  [unreachable]
+ mypy/plugins/functools.py:109: error: Right operand of "and" is never evaluated  [unreachable]
+ mypy/plugins/functools.py:110: error: Statement is unreachable  [unreachable]
+ mypy/test/update_data.py:16: error: Subclass of "DataSuiteCollector" and "DataFileCollector" cannot exist: would have incompatible method signatures  [unreachable]
+ mypy/test/update_data.py:17: error: Statement is unreachable  [unreachable]
+ mypy/plugins/default.py:553: error: Subclass of "TupleType" and "LiteralType" cannot exist: would have incompatible method signatures  [unreachable]
+ mypy/plugins/default.py:554: error: Statement is unreachable  [unreachable]
+ mypy/build.py:1068: error: Statement is unreachable  [unreachable]
+ mypy/build.py:1284: error: Statement is unreachable  [unreachable]
+ mypy/stubtest.py:340: error: Statement is unreachable  [unreachable]
+ mypy/stubtest.py:524: error: Statement is unreachable  [unreachable]
+ mypy/test/testpep561.py:181: error: Statement is unreachable  [unreachable]
+ mypy/test/testmerge.py:178: error: Statement is unreachable  [unreachable]
+ mypy/test/testfinegrained.py:78: error: Statement is unreachable  [unreachable]

pywin32 (https://github.com/mhammond/pywin32)
+ win32/Lib/sspi.py:375:59: error: Right operand of "and" is never evaluated  [unreachable]
+ com/win32comext/mapi/__init__.py:1:15: error: Subclass of "List[str]" and "str" cannot exist: would have incompatible method signatures  [unreachable]
+ com/win32comext/mapi/__init__.py:3:5: error: Statement is unreachable  [unreachable]
+ com/win32comext/adsi/__init__.py:4:15: error: Subclass of "List[str]" and "str" cannot exist: would have incompatible method signatures  [unreachable]
+ com/win32comext/adsi/__init__.py:6:5: error: Statement is unreachable  [unreachable]
+ com/win32comext/axscript/client/error.py:101:13: error: Statement is unreachable  [unreachable]
+ com/win32comext/axscript/client/framework.py:1120:13: error: Statement is unreachable  [unreachable]

artigraph (https://github.com/artigraph/artigraph)
+ src/arti/internal/type_hints.py:50: error: Subclass of "type" and "TypeVar" cannot exist: "TypeVar" is final  [unreachable]
+ src/arti/internal/type_hints.py:51: error: Statement is unreachable  [unreachable]
+ src/arti/internal/type_hints.py:58: error: Statement is unreachable  [unreachable]
+ src/arti/types/python.py:68: error: Subclass of "Type" and "_ContainerMixin" cannot exist: would have incompatible method signatures  [unreachable]
+ src/arti/types/python.py:69: error: Statement is unreachable  [unreachable]
+ src/arti/views/__init__.py:71: error: Statement is unreachable  [unreachable]
+ src/arti/views/__init__.py:78: error: Statement is unreachable  [unreachable]
+ src/arti/views/__init__.py:95: error: Statement is unreachable  [unreachable]
+ src/arti/types/pydantic.py:25: error: Subclass of "Type" and "_NamedMixin" cannot exist: would have incompatible method signatures  [unreachable]
+ src/arti/types/pydantic.py:26: error: Statement is unreachable  [unreachable]
+ src/arti/types/pyarrow.py:291: error: Subclass of "Type" and "_TimeMixin" cannot exist: would have incompatible method signatures  [unreachable]
+ src/arti/types/pyarrow.py:292: error: Statement is unreachable  [unreachable]
+ src/arti/types/bigquery.py:100: error: Subclass of "Type" and "_TimeMixin" cannot exist: would have incompatible method signatures  [unreachable]
+ src/arti/types/bigquery.py:101: error: Statement is unreachable  [unreachable]
+ tests/arti/internal/test_utils.py:158: error: Statement is unreachable  [unreachable]

pip (https://github.com/pypa/pip)
+ src/pip/_internal/utils/glibc.py:69: error: Statement is unreachable  [unreachable]
+ src/pip/_internal/utils/hashes.py:41: error: Statement is unreachable  [unreachable]
+ src/pip/_internal/build_env.py:199: error: Statement is unreachable  [unreachable]
+ src/pip/_internal/utils/unpacking.py:73: error: Statement is unreachable  [unreachable]
+ src/pip/_internal/req/req_file.py:490: error: Statement is unreachable  [unreachable]
+ src/pip/_internal/network/auth.py:132: error: Statement is unreachable  [unreachable]
+ src/pip/_internal/network/auth.py:150: error: Statement is unreachable  [unreachable]
+ src/pip/_internal/resolution/resolvelib/base.py:42: error: Statement is unreachable  [unreachable]
+ src/pip/_internal/resolution/legacy/resolver.py:454: error: Statement is unreachable  [unreachable]
+ src/pip/_internal/resolution/legacy/resolver.py:472: error: Statement is unreachable  [unreachable]

packaging (https://github.com/pypa/packaging)
+ src/packaging/version.py:80: error: Statement is unreachable  [unreachable]
+ src/packaging/version.py:86: error: Statement is unreachable  [unreachable]
+ src/packaging/version.py:98: error: Statement is unreachable  [unreachable]
+ src/packaging/version.py:104: error: Statement is unreachable  [unreachable]
+ src/packaging/_manylinux.py:143: error: Statement is unreachable  [unreachable]
+ src/packaging/specifiers.py:806: error: Statement is unreachable  [unreachable]
+ src/packaging/markers.py:317: error: Statement is unreachable  [unreachable]
+ src/packaging/metadata.py:335: error: Subclass of "str" and "Header" cannot exist: would have incompatible method signatures  [unreachable]
+ src/packaging/metadata.py:339: error: Statement is unreachable  [unreachable]

mongo-python-driver (https://github.com/mongodb/mongo-python-driver)
+ bson/binary.py:492: error: Statement is unreachable  [unreachable]
+ bson/decimal128.py:226: error: Statement is unreachable  [unreachable]
+ pymongo/synchronous/periodic_executor.py:202: error: Statement is unreachable  [unreachable]
+ pymongo/asynchronous/periodic_executor.py:202: error: Statement is unreachable  [unreachable]
+ pymongo/auth_shared.py:118: error: Statement is unreachable  [unreachable]
+ pymongo/auth_shared.py:157: error: Statement is unreachable  [unreachable]
+ pymongo/synchronous/topology.py:124: error: Statement is unreachable  [unreachable]
+ pymongo/synchronous/topology.py:140: error: Statement is unreachable  [unreachable]
+ pymongo/synchronous/topology.py:159: error: Statement is unreachable  [unreachable]
+ pymongo/synchronous/topology.py:183: error: Statement is unreachable  [unreachable]
+ pymongo/synchronous/topology.py:483: error: Statement is unreachable  [unreachable]
+ pymongo/synchronous/topology.py:496: error: Statement is unreachable  [unreachable]
+ pymongo/synchronous/topology.py:562: error: Statement is unreachable  [unreachable]
+ pymongo/synchronous/topology.py:709: error: Statement is unreachable  [unreachable]
+ pymongo/synchronous/topology.py:917: error: Statement is unreachable  [unreachable]
+ pymongo/synchronous/pool.py:336: error: Statement is unreachable  [unreachable]
+ pymongo/synchronous/pool.py:1530: error: Statement is unreachable  [unreachable]
+ pymongo/synchronous/monitor.py:510: error: Statement is unreachable  [unreachable]
+ pymongo/synchronous/mongo_client.py:2436: error: Statement is unreachable  [unreachable]
+ pymongo/synchronous/database.py:129: error: Statement is unreachable  [unreachable]
+ pymongo/synchronous/collection.py:239: error: Statement is unreachable  [unreachable]
+ pymongo/synchronous/client_session.py:878: error: Statement is unreachable  [unreachable]
+ pymongo/synchronous/client_session.py:1050: error: Statement is unreachable  [unreachable]
+ pymongo/synchronous/bulk.py:214: error: Statement is unreachable  [unreachable]
+ pymongo/synchronous/bulk.py:481: error: Statement is unreachable  [unreachable]
+ pymongo/synchronous/bulk.py:618: error: Statement is unreachable  [unreachable]
+ pymongo/asynchronous/topology.py:124: error: Statement is unreachable  [unreachable]
+ pymongo/asynchronous/topology.py:140: error: Statement is unreachable  [unreachable]
+ pymongo/asynchronous/topology.py:159: error: Statement is unreachable  [unreachable]
+ pymongo/asynchronous/topology.py:183: error: Statement is unreachable  [unreachable]
+ pymongo/asynchronous/topology.py:483: error: Statement is unreachable  [unreachable]
+ pymongo/asynchronous/topology.py:496: error: Statement is unreachable  [unreachable]
+ pymongo/asynchronous/topology.py:562: error: Statement is unreachable  [unreachable]
+ pymongo/asynchronous/topology.py:711: error: Statement is unreachable  [unreachable]
+ pymongo/asynchronous/topology.py:919: error: Statement is unreachable  [unreachable]
+ pymongo/asynchronous/pool.py:336: error: Statement is unreachable  [unreachable]
+ pymongo/asynchronous/pool.py:1536: error: Statement is unreachable  [unreachable]

... (truncated 130 lines) ...```

[johng]

This would be a breaking change so feel free to reject, and can with draw issue if so

[cdce8p]

warn-unreachable is nice but form my experience often not completely accurate, unfortunately. It's fine to use with type: ignore[unreachable] but I'm not sure it's ready for --strict mode just yet.