Emit redundant-expr warnings for if statements that are always true or always false.

[tyralla]

Fixes #19728

And thereby implements the two XXX comments of TypeChecker.visit_if_stmt.

The only surprise I encountered is that we must take care of while statements here, too, because while statements are transformed to if statements during type checking. It seems right to me to only emit warnings for while False but not for while True.

@A5rocks: Are you aware of other, uncovered special cases?

[tyralla]

Oh, 57 errors for Mypy itself, e.g. if TYPE_CHECKING. I will rethink this tomorrow...

[A5rocks]

We already kind of have a distinction between things that are true at compile time and run time for unreachability reporting, maybe that has a nice way to do that here? Probably not though.

(It's been too long for me to remember any special cases...)

[github-actions]

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

typeshed-stats (https://github.com/AlexWaygood/typeshed-stats)
+ src/typeshed_stats/gather.py:1226: error: If condition is always false  [redundant-expr]
+ src/typeshed_stats/gather.py:1245: error: If condition is always false  [redundant-expr]

aiohttp (https://github.com/aio-libs/aiohttp)
+ aiohttp/client_exceptions.py:323:4: error: If condition is always true  [redundant-expr]
+ aiohttp/client_exceptions.py:323:4: note: See https://mypy.rtfd.io/en/stable/_refs.html#code-redundant-expr for more info
+ aiohttp/helpers.py:127:12: error: If condition is always false  [redundant-expr]
+ aiohttp/helpers.py:130:12: error: If condition is always false  [redundant-expr]
+ aiohttp/helpers.py:170:12: error: If condition is always false  [redundant-expr]
+ aiohttp/helpers.py:267:8: error: If condition is always false  [redundant-expr]
+ aiohttp/helpers.py:877:14: error: If condition is always true  [redundant-expr]
+ aiohttp/cookiejar.py:297:12: error: If condition is always false  [redundant-expr]
+ aiohttp/cookiejar.py:485:15: error: While condition is always false  [redundant-expr]
+ aiohttp/payload.py:132:14: error: If condition is always true  [redundant-expr]
+ aiohttp/payload.py:352:14: error: If condition is always true  [redundant-expr]
+ aiohttp/payload.py:962:12: error: If condition is always false  [redundant-expr]
+ aiohttp/formdata.py:59:12: error: If condition is always false  [redundant-expr]
+ aiohttp/formdata.py:69:16: error: If condition is always false  [redundant-expr]
+ aiohttp/multipart.py:660:12: error: If condition is always false  [redundant-expr]
+ aiohttp/connector.py:159:12: error: If condition is always true  [redundant-expr]
+ aiohttp/connector.py:812:8: error: If condition is always false  [redundant-expr]
+ aiohttp/connector.py:907:12: error: If condition is always false  [redundant-expr]
+ aiohttp/connector.py:1165:12: error: If condition is always false  [redundant-expr]
+ aiohttp/client_ws.py:243:12: error: If condition is always false  [redundant-expr]
+ aiohttp/client_ws.py:250:12: error: If condition is always false  [redundant-expr]
+ aiohttp/client_reqrep.py:169:4: error: If condition is always true  [redundant-expr]
+ aiohttp/client_reqrep.py:275:12: error: If condition is always true  [redundant-expr]
+ aiohttp/client_reqrep.py:1072:12: error: If condition is always false  [redundant-expr]
+ aiohttp/client_reqrep.py:1227:12: error: If condition is always false  [redundant-expr]
+ aiohttp/client_middleware_digest_auth.py:178:12: error: If condition is always false  [redundant-expr]
+ aiohttp/client_middleware_digest_auth.py:181:12: error: If condition is always false  [redundant-expr]
+ aiohttp/client.py:306:12: error: If condition is always false  [redundant-expr]
+ aiohttp/client.py:462:12: error: If condition is always false  [redundant-expr]
+ aiohttp/client.py:841:16: error: If condition is always false  [redundant-expr]
+ aiohttp/client.py:948:16: error: If condition is always true  [redundant-expr]
+ aiohttp/client.py:996:12: error: If condition is always false  [redundant-expr]
+ aiohttp/web_response.py:267:14: error: If condition is always true  [redundant-expr]
+ aiohttp/web_response.py:555:20: error: If condition is always false  [redundant-expr]
+ aiohttp/web_fileresponse.py:328:16: error: If condition is always true  [redundant-expr]
+ aiohttp/web_ws.py:415:12: error: If condition is always false  [redundant-expr]
+ aiohttp/web_ws.py:424:12: error: If condition is always false  [redundant-expr]
+ aiohttp/web_urldispatcher.py:778:12: error: If condition is always false  [redundant-expr]
+ aiohttp/web_protocol.py:715:16: error: If condition is always false  [redundant-expr]
+ aiohttp/web_app.py:283:12: error: If condition is always false  [redundant-expr]
+ aiohttp/web_app.py:306:12: error: If condition is always false  [redundant-expr]
+ aiohttp/web_runner.py:263:20: error: If condition is always true  [redundant-expr]
+ aiohttp/web_runner.py:377:12: error: If condition is always false  [redundant-expr]
+ aiohttp/worker.py:211:12: error: If condition is always false  [redundant-expr]
+ aiohttp/test_utils.py:278:12: error: If condition is always false  [redundant-expr]
+ aiohttp/pytest_plugin.py:416:14: error: If condition is always true  [redundant-expr]

mypy (https://github.com/python/mypy)
+ mypyc/codegen/literals.py:66: error: If condition is always true  [redundant-expr]
+ mypyc/codegen/literals.py:66: note: See https://mypy.rtfd.io/en/stable/_refs.html#code-redundant-expr for more info
+ mypyc/codegen/literals.py:105: error: If condition is always true  [redundant-expr]
+ mypy/nodes.py:4533: error: If condition is always true  [redundant-expr]
+ mypy/nodes.py:4582: error: If condition is always true  [redundant-expr]
+ mypy/nodes.py:4626: error: If condition is always true  [redundant-expr]
+ mypy/nodes.py:4831: error: If condition is always true  [redundant-expr]
+ mypy/traverser.py:126: error: If condition is always true  [redundant-expr]
+ mypy/traverser.py:195: error: If condition is always true  [redundant-expr]
+ mypy/traverser.py:201: error: If condition is always true  [redundant-expr]
+ mypy/server/astmerge.py:448: error: If condition is always true  [redundant-expr]
+ mypy/server/astmerge.py:460: error: If condition is always true  [redundant-expr]
+ mypy/server/astmerge.py:477: error: If condition is always true  [redundant-expr]
+ mypy/fixup.py:280: error: If condition is always true  [redundant-expr]
+ mypy/fixup.py:282: error: If condition is always true  [redundant-expr]
+ mypy/fixup.py:315: error: If condition is always true  [redundant-expr]
+ mypy/fixup.py:322: error: If condition is always true  [redundant-expr]
+ mypy/fixup.py:362: error: If condition is always true  [redundant-expr]
+ mypy/errors.py:215: error: If condition is always true  [redundant-expr]
+ mypyc/ir/pprint.py:217: error: If condition is always true  [redundant-expr]
+ mypy/modulefinder.py:106: error: If condition is always true  [redundant-expr]
+ mypy/fastparse.py:1525: error: If condition is always false  [redundant-expr]
+ mypy/fastparse.py:1669: error: If condition is always true  [redundant-expr]
+ mypy/fastparse.py:2077: error: If condition is always true  [redundant-expr]
+ mypy/constraints.py:133: error: If condition is always false  [redundant-expr]
+ mypy/constraints.py:133: note: Error code "redundant-expr" not covered by "type: ignore" comment
+ mypy/constraints.py:188: error: If condition is always true  [redundant-expr]
+ mypy/messages.py:1254: error: If condition is always true  [redundant-expr]
+ mypy/messages.py:2778: error: If condition is always false  [redundant-expr]
+ mypyc/codegen/emitfunc.py:699: error: If condition is always true  [redundant-expr]
+ mypyc/analysis/ircheck.py:307: error: If condition is always true  [redundant-expr]
+ mypy/plugins/enums.py:228: error: If condition is always true  [redundant-expr]
+ mypy/checkpattern.py:219: error: If condition is always true  [redundant-expr]
+ mypy/server/astdiff.py:259: error: If condition is always true  [redundant-expr]
+ mypy/checkstrformat.py:687: error: If condition is always true  [redundant-expr]
+ mypy/checkstrformat.py:850: error: If condition is always true  [redundant-expr]
+ mypy/plugins/dataclasses.py:140: error: If condition is always true  [redundant-expr]
+ mypy/semanal.py:1003: error: If condition is always true  [redundant-expr]
+ mypy/semanal.py:1403: error: If condition is always true  [redundant-expr]
+ mypy/semanal.py:1494: error: If condition is always true  [redundant-expr]
+ mypy/semanal.py:1504: error: If condition is always true  [redundant-expr]
+ mypy/semanal.py:3872: error: If condition is always true  [redundant-expr]
+ mypy/semanal.py:5817: error: If condition is always true  [redundant-expr]
+ mypy/checkexpr.py:3545: error: If condition is always true  [redundant-expr]
+ mypy/checker.py:894: error: If condition is always true  [redundant-expr]
+ mypy/checker.py:2508: error: If condition is always true  [redundant-expr]
+ mypy/checker.py:8654: error: If condition is always true  [redundant-expr]
+ mypy/checker.py:8655: error: If condition is always true  [redundant-expr]
+ mypy/checker.py:9029: error: If condition is always true  [redundant-expr]
+ mypy/build.py:1087: error: If condition is always false  [redundant-expr]
+ mypy/build.py:1318: error: If condition is always false  [redundant-expr]
+ mypyc/irbuild/prepare.py:263: error: If condition is always true  [redundant-expr]
+ mypy/stubtest.py:349: error: If condition is always false  [redundant-expr]
+ mypy/stubtest.py:632: error: If condition is always false  [redundant-expr]
+ mypy/stubtest.py:1920: error: If condition is always true  [redundant-expr]
+ mypyc/irbuild/builder.py:621: error: If condition is always true  [redundant-expr]
+ mypyc/irbuild/builder.py:719: error: If condition is always true  [redundant-expr]
+ mypyc/irbuild/expression.py:919: error: If condition is always true  [redundant-expr]

pyproject-metadata (https://github.com/pypa/pyproject-metadata)
+ pyproject_metadata/pyproject.py:77: error: If condition is always true  [redundant-expr]
+ pyproject_metadata/pyproject.py:86: error: If condition is always false  [redundant-expr]
+ pyproject_metadata/pyproject.py:100: error: If condition is always false  [redundant-expr]
+ pyproject_metadata/pyproject.py:105: error: If condition is always false  [redundant-expr]
+ pyproject_metadata/pyproject.py:168: error: If condition is always true  [redundant-expr]
+ pyproject_metadata/pyproject.py:249: error: If condition is always true  [redundant-expr]
+ pyproject_metadata/pyproject.py:333: error: If condition is always false  [redundant-expr]
+ pyproject_metadata/pyproject.py:341: error: If condition is always false  [redundant-expr]
+ pyproject_metadata/pyproject.py:351: error: If condition is always false  [redundant-expr]
+ pyproject_metadata/pyproject.py:383: error: If condition is always false  [redundant-expr]
+ pyproject_metadata/pyproject.py:396: error: If condition is always false  [redundant-expr]
+ pyproject_metadata/pyproject.py:408: error: If condition is always false  [redundant-expr]
+ pyproject_metadata/__init__.py:369: error: If condition is always false  [redundant-expr]

CPython (cases_generator) (https://github.com/python/cpython)
+ Tools/cases_generator/cwriter.py:122: error: If condition is always true  [redundant-expr]

rich (https://github.com/Textualize/rich)
+ rich/text.py:978: error: If condition is always false  [redundant-expr]
+ rich/text.py:990: error: If condition is always true  [redundant-expr]
+ rich/text.py:1241: error: If condition is always true  [redundant-expr]
+ rich/rule.py:96: error: If condition is always true  [redundant-expr]
+ rich/padding.py:71: error: If condition is always true  [redundant-expr]
+ rich/highlighter.py:34: error: If condition is always true  [redundant-expr]
+ rich/console.py:1791: error: If condition is always false  [redundant-expr]
+ rich/box.py:144: error: If condition is always true  [redundant-expr]
+ rich/align.py:178: error: If condition is always true  [redundant-expr]
+ rich/file_proxy.py:29: error: If condition is always false  [redundant-expr]

pyodide (https://github.com/pyodide/pyodide)
+ src/py/_pyodide/jsbind.py:113: error: If condition is always true  [redundant-expr]
+ src/py/_pyodide/_importhook.py:71: error: If condition is always false  [redundant-expr]
+ pyodide-build/pyodide_build/vendor/loky.py:166: error: If condition is always false  [redundant-expr]
+ pyodide-build/pyodide_build/common.py:268: error: If condition is always true  [redundant-expr]
+ pyodide-build/pyodide_build/recipe/skeleton.py:126: error: If condition is always true  [redundant-expr]
+ src/py/pyodide/console.py:112: error: If condition is always false  [redundant-expr]
+ src/py/pyodide/code.py:24: error: If condition is always false  [redundant-expr]
+ src/py/pyodide/_run_js.py:13: error: If condition is always false  [redundant-expr]
+ src/py/pyodide/http/_pyxhr.py:174: error: If condition is always true  [redundant-expr]

CPython (peg_generator) (https://github.com/python/cpython)
+ Tools/peg_generator/pegen/c_generator.py:281: error: If condition is always true  [redundant-expr]

packaging (https://github.com/pypa/packaging)
+ src/packaging/version.py:79: error: If condition is always false  [redundant-expr]
+ src/packaging/version.py:85: error: If condition is always false  [redundant-expr]
+ src/packaging/version.py:97: error: If condition is always false  [redundant-expr]
+ src/packaging/version.py:103: error: If condition is always false  [redundant-expr]
+ src/packaging/_manylinux.py:142: error: If condition is always false  [redundant-expr]
+ src/packaging/specifiers.py:785: error: If condition is always false  [redundant-expr]
+ src/packaging/markers.py:344: error: If condition is always false  [redundant-expr]
+ src/packaging/metadata.py:386: error: If condition is always false  [redundant-expr]

poetry (https://github.com/python-poetry/poetry)
+ src/poetry/utils/_compat.py:39: error: If condition is always false  [redundant-expr]
+ src/poetry/pyproject/toml.py:48: error: If condition is always false  [redundant-expr]
+ src/poetry/utils/authenticator.py:164: error: If condition is always true  [redundant-expr]
+ src/poetry/utils/authenticator.py:263: error: If condition is always true  [redundant-expr]
+ src/poetry/config/source.py:23: error: If condition is always false  [redundant-expr]
+ src/poetry/utils/env/env_manager.py:196: error: If condition is always false  [redundant-expr]
+ src/poetry/utils/env/env_manager.py:377: error: If condition is always false  [redundant-expr]
+ src/poetry/installation/executor.py:819: error: If condition is always false  [redundant-expr]
+ src/poetry/plugins/plugin_manager.py:85: error: If condition is always false  [redundant-expr]
+ src/poetry/console/commands/remove.py:70: error: If condition is always false  [redundant-expr]
+ tests/console/commands/test_install.py:155: error: If condition is always false  [redundant-expr]
+ tests/console/commands/test_build.py:184: error: If condition is always false  [redundant-expr]
+ src/poetry/console/commands/add.py:329: error: If condition is always true  [redundant-expr]

archinstall (https://github.com/archlinux/archinstall)
+ archinstall/tui/curses_menu.py:908: error: If condition is always false  [redundant-expr]
+ archinstall/lib/output.py:45: error: If condition is always true  [redundant-expr]
+ archinstall/lib/general.py:345: error: If condition is always true  [redundant-expr]
+ archinstall/lib/models/authentication.py:47: error: If condition is always false  [redundant-expr]
+ archinstall/lib/models/mirrors.py:100: error: If condition is always true  [redundant-expr]
+ archinstall/lib/models/device.py:321: error: If condition is always false  [redundant-expr]
+ archinstall/lib/models/device.py:1178: error: If condition is always false  [redundant-expr]
+ archinstall/lib/luks.py:46: error: If condition is always false  [redundant-expr]
+ archinstall/lib/installer.py:840: error: If condition is always true  [redundant-expr]
+ archinstall/lib/installer.py:946: error: If condition is always true  [redundant-expr]
+ archinstall/lib/authentication/authentication_menu.py:120: error: If condition is always true  [redundant-expr]
+ archinstall/lib/profile/profile_menu.py:142: error: If condition is always true  [redundant-expr]

yarl (https://github.com/aio-libs/yarl)
+ yarl/_quoting_py.py:43:12: error: If condition is always false  [redundant-expr]
+ yarl/_quoting_py.py:43:12: note: See https://mypy.rtfd.io/en/stable/_refs.html#code-redundant-expr for more info
+ yarl/_quoting_py.py:144:12: error: If condition is always false  [redundant-expr]
+ yarl/_quoting_py.py:174:28: error: If condition is always false  [redundant-expr]
+ yarl/_quoting_py.py:179:28: error: If condition is always false  [redundant-expr]
+ yarl/_url.py:408:12: error: If condition is always false  [redundant-expr]
+ yarl/_url.py:549:12: error: If condition is always false  [redundant-expr]
+ yarl/_url.py:1059:12: error: If condition is always false  [redundant-expr]
+ yarl/_url.py:1082:14: error: If condition is always true  [redundant-expr]
+ yarl/_url.py:1104:14: error: If condition is always true  [redundant-expr]
+ yarl/_url.py:1125:12: error: If condition is always false  [redundant-expr]
+ yarl/_url.py:1319:14: error: If condition is always false  [redundant-expr]
+ yarl/_url.py:1344:12: error: If condition is always false  [redundant-expr]
+ yarl/_url.py:1380:12: error: If condition is always false  [redundant-expr]

build (https://github.com/pypa/build)
+ src/build/__main__.py:187: error: If condition is always true  [redundant-expr]

xarray (https://github.com/pydata/xarray)
+ xarray/backends/lru_cache.py: note: In member "__init__" of class "LRUCache":
+ xarray/backends/lru_cache.py:44: error: If condition is always false  [redundant-expr]
+ xarray/compat/npcompat.py: note: In function "isdtype":
+ xarray/compat/npcompat.py:72: error: If condition is always false  [redundant-expr]
+ xarray/namedarray/utils.py: note: In function "drop_missing_dims":
+ xarray/namedarray/utils.py:144: error: If condition is always true  [redundant-expr]
+ xarray/core/utils.py: note: In function "equivalent":
+ xarray/core/utils.py:266: error: If condition is always false  [redundant-expr]
+ xarray/core/utils.py: note: In function "drop_dims_from_indexers":
+ xarray/core/utils.py:925: error: If condition is always true  [redundant-expr]
+ xarray/namedarray/pycompat.py: note: In member "__init__" of class "DuckArrayModule":
+ xarray/namedarray/pycompat.py:53: error: If condition is always true  [redundant-expr]
+ xarray/core/treenode.py: note: In member "_set_parent" of class "TreeNode":
+ xarray/core/treenode.py:101: error: If condition is always false  [redundant-expr]
+ xarray/core/treenode.py: note: In function "_validate_name":
+ xarray/core/treenode.py:668: error: If condition is always false  [redundant-expr]
+ xarray/backends/locks.py: note: In function "combine_locks":
+ xarray/backends/locks.py:267: error: If condition is always true  [redundant-expr]
+ xarray/namedarray/parallelcompat.py: note: In function "guess_chunkmanager":
+ xarray/namedarray/parallelcompat.py:133: error: If condition is always true  [redundant-expr]
+ xarray/core/indexing.py: note: In function "group_indexers_by_index":
+ xarray/core/indexing.py:147: error: If condition is always true  [redundant-expr]
+ xarray/core/indexing.py: note: In function "map_index_queries":
+ xarray/core/indexing.py:197: error: If condition is always false  [redundant-expr]
+ xarray/core/indexing.py: note: In member "__init__" of class "BasicIndexer":
+ xarray/core/indexing.py:461: error: If condition is always false  [redundant-expr]
+ xarray/core/indexing.py:468: error: If condition is always true  [redundant-expr]
+ xarray/core/indexing.py: note: In member "__init__" of class "OuterIndexer":
+ xarray/core/indexing.py:494: error: If condition is always false  [redundant-expr]
+ xarray/core/indexing.py: note: In member "__init__" of class "VectorizedIndexer":
+ xarray/core/indexing.py:536: error: If condition is always false  [redundant-expr]
+ xarray/core/indexing.py: note: In function "_decompose_outer_indexer":
+ xarray/core/indexing.py:1398: error: If condition is always false  [redundant-expr]
+ xarray/core/indexing.py: note: At top level:
+ xarray/namedarray/core.py: note: In function "from_array":
+ xarray/namedarray/core.py:190: error: If condition is always false  [redundant-expr]
+ xarray/namedarray/core.py: note: At top level:
+ xarray/core/indexes.py: note: In member "from_variables" of class "PandasIndex":
+ xarray/core/indexes.py:722: error: If condition is always false  [redundant-expr]
+ xarray/core/indexes.py: note: In member "to_pandas_indexes" of class "Indexes":
+ xarray/core/indexes.py:1853: error: If condition is always false  [redundant-expr]
+ xarray/core/indexes.py:1853: error: If condition is always true  [redundant-expr]
+ xarray/core/indexes.py:1855: error: If condition is always true  [redundant-expr]
+ xarray/core/indexes.py: note: In member "copy_indexes" of class "Indexes":
+ xarray/core/indexes.py:1881: error: If condition is always false  [redundant-expr]
+ xarray/core/indexes.py:1881: error: If condition is always true  [redundant-expr]
+ xarray/core/formatting.py: note: In function "summarize_variable":
+ xarray/core/formatting.py:340: error: If condition is always false  [redundant-expr]
+ xarray/core/common.py: note: In member "_resample" of class "DataWithCoords":
+ xarray/core/common.py:1112: error: If condition is always true  [redundant-expr]
+ xarray/core/common.py: note: In function "full_like":
+ xarray/core/common.py:1741: error: If condition is always true  [redundant-expr]
+ xarray/plot/facetgrid.py: note: In member "set_axis_labels" of class "FacetGrid":
+ xarray/plot/facetgrid.py:852: error: If condition is always false  [redundant-expr]
+ xarray/plot/facetgrid.py: note: At top level:
+ xarray/plot/facetgrid.py: note: In function "_easy_facetgrid":
+ xarray/plot/facetgrid.py:1082: error: If condition is always true  [redundant-expr]
+ xarray/core/variable.py: note: In function "_maybe_wrap_data":
+ xarray/core/variable.py:202: error: If condition is always true  [redundant-expr]
+ xarray/core/variable.py: note: In function "as_compatible_data":
+ xarray/core/variable.py:290: error: If condition is always true  [redundant-expr]
+ xarray/core/variable.py: note: In member "_pad_options_dim_to_index" of class "Variable":
+ xarray/core/variable.py:1225: error: If condition is always false  [redundant-expr]
+ xarray/core/variable.py: note: At top level:
+ xarray/structure/merge.py: note: In function "coerce_pandas_values":
+ xarray/structure/merge.py:530: error: If condition is always false  [redundant-expr]
+ xarray/computation/computation.py: note: In function "cov":
+ xarray/computation/computation.py:147: error: If condition is always false  [redundant-expr]
+ xarray/computation/computation.py: note: In function "corr":
+ xarray/computation/computation.py:250: error: If condition is always false  [redundant-expr]
+ xarray/core/coordinates.py: note: In member "equals" of class "Coordinates":
+ xarray/core/coordinates.py:477: error: If condition is always false  [redundant-expr]
+ xarray/core/coordinates.py: note: In member "identical" of class "Coordinates":
+ xarray/core/coordinates.py:488: error: If condition is always false  [redundant-expr]
+ xarray/computation/apply_ufunc.py: note: In function "apply_dict_of_variables_vfunc":
+ xarray/computation/apply_ufunc.py:455: error: If condition is always true  [redundant-expr]
+ xarray/coding/cftimeindex.py: note: In member "shift" of class "CFTimeIndex":
+ xarray/coding/cftimeindex.py:508: error: If condition is always true  [redundant-expr]
+ xarray/conventions.py: note: In function "ensure_not_multiindex":
+ xarray/conventions.py:56: error: If condition is always false  [redundant-expr]
+ xarray/conventions.py: note: In function "decode_cf":
+ xarray/conventions.py:578: error: If condition is always true  [redundant-expr]
+ xarray/coding/cftime_offsets.py: note: In member "__init__" of class "BaseCFTimeOffset":
+ xarray/coding/cftime_offsets.py:114: error: If condition is always false  [redundant-expr]
+ xarray/coding/cftime_offsets.py: note: In member "__mul__" of class "BaseCFTimeOffset":
+ xarray/coding/cftime_offsets.py:149: error: If condition is always false  [redundant-expr]
+ xarray/coding/cftime_offsets.py: note: In member "__mul__" of class "Tick":
+ xarray/coding/cftime_offsets.py:218: error: If condition is always false  [redundant-expr]
+ xarray/coding/cftime_offsets.py: note: In function "_get_day_of_month":
+ xarray/coding/cftime_offsets.py:256: error: If condition is always true  [redundant-expr]
+ xarray/coding/cftime_offsets.py: note: In function "_shift_month":
+ xarray/coding/cftime_offsets.py:311: error: If condition is always true  [redundant-expr]
+ xarray/coding/cftime_offsets.py: note: In function "_validate_month":
+ xarray/coding/cftime_offsets.py:363: error: If condition is always false  [redundant-expr]
+ xarray/coding/cftime_offsets.py: note: In function "_cftime_range":
+ xarray/coding/cftime_offsets.py:1206: error: If condition is always false  [redundant-expr]
+ xarray/coding/cftime_offsets.py: note: In function "_legacy_to_new_freq":
+ xarray/coding/cftime_offsets.py:1510: error: If condition is always true  [redundant-expr]
+ xarray/plot/dataarray_plot.py: note: In function "line":
+ xarray/plot/dataarray_plot.py:521: error: If condition is always true  [redundant-expr]
+ xarray/plot/dataarray_plot.py:524: error: If condition is always true  [redundant-expr]
+ xarray/plot/dataarray_plot.py: note: At top level:
+ xarray/plot/dataarray_plot.py: note: In function "_add_labels":
+ xarray/plot/dataarray_plot.py:1110: error: If condition is always true  [redundant-expr]
+ xarray/plot/dataarray_plot.py: note: In function "_plot2d":
+ xarray/plot/dataarray_plot.py:1606: error: If condition is always false  [redundant-expr]
+ xarray/core/resample_cftime.py: note: In function "_get_time_bins":
+ xarray/core/resample_cftime.py:221: error: If condition is always false  [redundant-expr]
+ xarray/core/groupby.py: note: In function "_consolidate_slices":
+ xarray/core/groupby.py:143: error: If condition is always false  [redundant-expr]
+ xarray/core/groupby.py: note: In member "__post_init__" of class "ResolvedGrouper":
+ xarray/core/groupby.py:333: error: If condition is always false  [redundant-expr]
+ xarray/core/groupby.py: note: In function "_parse_group_and_groupers":
+ xarray/core/groupby.py:403: error: If condition is always false  [redundant-expr]
+ xarray/core/groupby.py:408: error: If condition is always false  [redundant-expr]
+ xarray/core/groupby.py: note: In function "_validate_groupby_squeeze":
+ xarray/core/groupby.py:453: error: If condition is always false  [redundant-expr]
+ xarray/core/groupby.py: note: At top level:
+ xarray/core/dataset.py: note: In member "head" of class "Dataset":
+ xarray/core/dataset.py:3110: error: If condition is always false  [redundant-expr]
+ xarray/core/dataset.py: note: In member "tail" of class "Dataset":
+ xarray/core/dataset.py:3198: error: If condition is always false  [redundant-expr]
+ xarray/core/dataset.py: note: In member "thin" of class "Dataset":
+ xarray/core/dataset.py:3284: error: If condition is always false  [redundant-expr]
+ xarray/core/dataset.py: note: In member "expand_dims" of class "Dataset":
+ xarray/core/dataset.py:4576: error: If condition is always true  [redundant-expr]
+ xarray/core/dataset.py: note: In member "set_xindex" of class "Dataset":
+ xarray/core/dataset.py:4986: error: If condition is always false  [redundant-expr]
+ xarray/core/dataset.py: note: In member "transpose" of class "Dataset":
+ xarray/core/dataset.py:6237: error: If condition is always false  [redundant-expr]
+ xarray/core/dataset.py: note: In member "dropna" of class "Dataset":
+ xarray/core/dataset.py:6378: error: If condition is always true  [redundant-expr]
+ xarray/core/dataset.py: note: In member "diff" of class "Dataset":
+ xarray/core/dataset.py:7838: error: If condition is always true  [redundant-expr]
+ xarray/core/dataset.py: note: In member "sortby" of class "Dataset":
+ xarray/core/dataset.py:8102: error: If condition is always true  [redundant-expr]
+ xarray/core/dataarray.py: note: In member "_inplace_binary_op" of class "DataArray":
+ xarray/core/dataarray.py:4910: error: If condition is always false  [redundant-expr]
+ xarray/core/dataarray.py: note: In member "dot" of class "DataArray":
+ xarray/core/dataarray.py:5184: error: If condition is always false  [redundant-expr]
+ xarray/core/dataarray.py:5184: error: If condition is always true  [redundant-expr]
+ xarray/core/dataarray.py:5188: error: If condition is always false  [redundant-expr]
+ xarray/groupers.py: note: In member "_init_properties" of class "TimeResampler":
+ xarray/groupers.py:524: error: If condition is always false  [redundant-expr]
+ xarray/indexes/nd_point_index.py: note: In member "from_variables" of class "NDPointIndex":
+ xarray/indexes/nd_point_index.py:270: error: If condition is always false  [redundant-expr]
+ xarray/core/parallel.py: note: In function "check_result_variables":
+ xarray/core/parallel.py:50: error: If condition is always true  [redundant-expr]
+ xarray/core/parallel.py: note: In function "dataset_to_dataarray":
+ xarray/core/parallel.py:69: error: If condition is always false  [redundant-expr]
+ xarray/core/parallel.py: note: At top level:
+ xarray/core/parallel.py: note: In function "infer_template":
+ xarray/core/parallel.py:133: error: If condition is always false  [redundant-expr]
+ xarray/core/parallel.py: note: At top level:
+ xarray/core/parallel.py: note: In function "map_blocks":
+ xarray/core/parallel.py:395: error: If condition is always false  [redundant-expr]
+ xarray/core/parallel.py:399: error: If condition is always false  [redundant-expr]
+ xarray/core/parallel.py:403: error: If condition is always false  [redundant-expr]
+ xarray/core/parallel.py: note: At top level:
+ xarray/core/parallel.py: note: In function "map_blocks":
+ xarray/core/parallel.py:522: error: If condition is always true  [redundant-expr]
+ xarray/core/datatree.py: note: In function "_to_new_dataset":
+ xarray/core/datatree.py:140: error: If condition is always true  [redundant-expr]
+ xarray/core/datatree.py: note: In member "__getitem__" of class "DataTree":
+ xarray/core/datatree.py:967: error: If condition is always true  [redundant-expr]
+ xarray/core/datatree.py: note: In member "__setitem__" of class "DataTree":
+ xarray/core/datatree.py:1015: error: If condition is always true  [redundant-expr]
+ xarray/core/datatree.py: note: In function "update":
+ xarray/core/datatree.py:1079: error: If condition is always true  [redundant-expr]
+ xarray/testing/assertions.py: note: In function "assert_isomorphic":
+ xarray/testing/assertions.py:81: error: If condition is always true  [redundant-expr]
+ xarray/testing/assertions.py: note: In function "_assert_dataarray_invariants":
+ xarray/testing/assertions.py:431: error: If condition is always true  [redundant-expr]
+ xarray/testing/assertions.py: note: In function "_assert_dataset_invariants":
+ xarray/testing/assertions.py:466: error: If condition is always true  [redundant-expr]
+ xarray/testing/assertions.py: note: In function "_assert_internal_invariants":
+ xarray/testing/assertions.py:490: error: If condition is always true  [redundant-expr]
+ xarray/backends/common.py: note: In function "ensure_dtype_not_object":
+ xarray/backends/common.py:682: error: If condition is always false  [redundant-expr]
+ xarray/backends/common.py:682: error: If condition is always true  [redundant-expr]
+ xarray/backends/plugins.py: note: In function "get_backend":
+ xarray/backends/plugins.py:227: error: If condition is always true  [redundant-expr]
+ xarray/backends/api.py: note: In function "open_mfdataset":
+ xarray/backends/api.py:1676: error: If condition is always true  [redundant-expr]
+ xarray/computation/weighted.py: note: In member "__init__" of class "Weighted":
+ xarray/computation/weighted.py:170: error: If condition is always false  [redundant-expr]
+ xarray/computation/weighted.py: note: At top level:
+ xarray/computation/weighted.py: note: In function "_weighted_quantile":
+ xarray/computation/weighted.py:342: error: If condition is always true  [redundant-expr]
+ xarray/computation/rolling.py: note: In member "_numbagg_reduce" of class "DataArrayRolling":
+ xarray/computation/rolling.py:627: error: If condition is always false  [redundant-expr]
+ xarray/computation/rolling.py: note: In member "construct" of class "Coarsen":
+ xarray/computation/rolling.py:1191: error: If condition is always true  [redundant-expr]
+ xarray/computation/rolling.py:1191: error: If condition is always false  [redundant-expr]
+ xarray/computation/rolling.py:1215: error: If condition is always true  [redundant-expr]
+ xarray/computation/rolling.py:1215: error: If condition is always false  [redundant-expr]
+ xarray/tests/arrays.py: note: In function "broadcast_to":
+ xarray/tests/arrays.py:122: error: If condition is always false  [redundant-expr]
+ xarray/tests/arrays.py: note: In function "full_like":
+ xarray/tests/arrays.py:136: error: If condition is always false  [redundant-expr]
+ xarray/tests/test_namedarray.py: note: In function "check_duck_array_typevar":
+ xarray/tests/test_namedarray.py:96: error: If condition is always true  [redundant-expr]
+ xarray/tests/test_indexing.py: note: In member "test_group_indexers_by_index" of class "TestIndexers":
+ xarray/tests/test_indexing.py:104: error: If condition is always false  [redundant-expr]
+ xarray/tests/test_indexing.py: note: At top level:
+ xarray/tests/test_backends.py: note: In member "check_dtypes_roundtripped" of class "DatasetIOBase":
+ xarray/tests/test_backends.py:520: error: If condition is always false  [redundant-expr]
+ xarray/tests/test_backends.py: note: At top level:
+ xarray/testing/strategies.py: note: In function "variables":
+ xarray/testing/strategies.py:342: error: If condition is always false  [redundant-expr]

... (truncated 4 lines) ...

scikit-build-core (https://github.com/scikit-build/scikit-build-core)
+ src/scikit_build_core/settings/skbuild_overrides.py:219: error: If condition is always false  [redundant-expr]
+ src/scikit_build_core/_vendor/pyproject_metadata/pyproject.py:77: error: If condition is always true  [redundant-expr]
+ src/scikit_build_core/_vendor/pyproject_metadata/pyproject.py:86: error: If condition is always false  [redundant-expr]
+ src/scikit_build_core/_vendor/pyproject_metadata/pyproject.py:100: error: If condition is always false  [redundant-expr]
+ src/scikit_build_core/_vendor/pyproject_metadata/pyproject.py:105: error: If condition is always false  [redundant-expr]
+ src/scikit_build_core/_vendor/pyproject_metadata/pyproject.py:168: error: If condition is always true  [redundant-expr]
+ src/scikit_build_core/_vendor/pyproject_metadata/pyproject.py:249: error: If condition is always true  [redundant-expr]
+ src/scikit_build_core/_vendor/pyproject_metadata/pyproject.py:333: error: If condition is always false  [redundant-expr]
+ src/scikit_build_core/_vendor/pyproject_metadata/pyproject.py:341: error: If condition is always false  [redundant-expr]
+ src/scikit_build_core/_vendor/pyproject_metadata/pyproject.py:351: error: If condition is always false  [redundant-expr]
+ src/scikit_build_core/_vendor/pyproject_metadata/pyproject.py:383: error: If condition is always false  [redundant-expr]
+ src/scikit_build_core/_vendor/pyproject_metadata/pyproject.py:396: error: If condition is always false  [redundant-expr]
+ src/scikit_build_core/_vendor/pyproject_metadata/pyproject.py:408: error: If condition is always false  [redundant-expr]
+ src/scikit_build_core/_vendor/pyproject_metadata/__init__.py:369: error: If condition is always false  [redundant-expr]
+ src/scikit_build_core/setuptools/build_cmake.py:250: error: If condition is always false  [redundant-expr]
+ src/scikit_build_core/hatch/plugin.py:73: error: If condition is always false  [redundant-expr]
+ src/scikit_build_core/build/wheel.py:398: error: If condition is always true  [redundant-expr]
+ src/scikit_build_core/build/__main__.py:45: error: If condition is always true  [redundant-expr]

boostedblob (https://github.com/hauntsaninja/boostedblob)
+ boostedblob/boost.py:312: error: If condition is always false  [redundant-expr]
+ boostedblob/boost.py:578: error: If condition is always true  [redundant-expr]
+ boostedblob/boost.py:590: error: If condition is always true  [redundant-expr]
+ boostedblob/boost.py:603: error: If condition is always true  [redundant-expr]
+ boostedblob/path.py:88: error: If condition is always false  [redundant-expr]
+ boostedblob/path.py:168: error: If condition is always false  [redundant-expr]
+ boostedblob/path.py:237: error: If condition is always false  [redundant-expr]

nox (https://github.com/wntrblm/nox)
+ nox/sessions.py:613: error: If condition is always false  [redundant-expr]

[tyralla]

A few looks into the primer results (from bottom to top; without obvious repetitions):

nox

Mypy issues (in this case already under discussion in #11764).

x: str | None,
if callable(x):  # error: If condition is always false
    ...  # type: ignore[unreachable]

boostedblob

Additional runtime type checking.

def f(x: str | int) -> None:
    if not isinstance(x, str | int):  # error: If condition is always false
        raise ValueError

def g(x: str | int) -> None:
    if isinstance(x, str):
        return
    if isinstance(x, int):  # error: If condition is always true
       return
    raise AssertionError

scikit-build-core

Really redundant code (or at least one that needs explanations):

def f(env: dict[str, str] | None):
    if env:
        for key, value in env.items():
            if isinstance(value, bool):  # error: If condition is always false
                ...

import dataclasses

@dataclasses.dataclass
class Settings1:
    cmake: bool = False

@dataclasses.dataclass
class Settings2:
    cmake: bool = False

def f(s1: Settings1, s2: Settings2) -> None:
    if not s1.cmake or s2.cmake:
        ...
    if s2.cmake:  # error: If condition is always false
        ...

Based on these few examples, this PR seems correct. However, it somehow collides with exhaustiveness checking.