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Merged
merged 8 commits into from
Oct 4, 2025
Merged

Support error codes from plugins in options #19719

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3ebd792
Support error codes from plugins in options
sigvef Aug 23, 2025
9130edf
refactor error callback (#1)
belm0 Oct 3, 2025
60ab748
[pre-commit.ci] auto fixes from pre-commit.com hooks
pre-commit-ci[bot] Oct 3, 2025
53a65f2
fix type check
belm0 Oct 3, 2025
5d72e39
Update main.py
ilevkivskyi Oct 4, 2025
892ad6e
Update options.py
ilevkivskyi Oct 4, 2025
5de7da2
Update build.py
ilevkivskyi Oct 4, 2025
7691315
Update cmdline.test
ilevkivskyi Oct 4, 2025
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3 changes: 3 additions & 0 deletions mypy/build.py
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Original file line number Diff line number Diff line change
Expand Up @@ -504,6 +504,9 @@ def load_plugins(
"""
custom_plugins, snapshot = load_plugins_from_config(options, errors, stdout)

if options._on_plugins_loaded is not None:
options._on_plugins_loaded()

custom_plugins += extra_plugins

default_plugin: Plugin = DefaultPlugin(options)
Expand Down
19 changes: 4 additions & 15 deletions mypy/config_parser.py
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Original file line number Diff line number Diff line change
Expand Up @@ -8,8 +8,6 @@
import sys
from io import StringIO

from mypy.errorcodes import error_codes

if sys.version_info >= (3, 11):
import tomllib
else:
Expand Down Expand Up @@ -87,15 +85,6 @@ def complain(x: object, additional_info: str = "") -> Never:
complain(v)


def validate_codes(codes: list[str]) -> list[str]:
invalid_codes = set(codes) - set(error_codes.keys())
if invalid_codes:
raise argparse.ArgumentTypeError(
f"Invalid error code(s): {', '.join(sorted(invalid_codes))}"
)
return codes


def validate_package_allow_list(allow_list: list[str]) -> list[str]:
for p in allow_list:
msg = f"Invalid allow list entry: {p}"
Expand Down Expand Up @@ -209,8 +198,8 @@ def split_commas(value: str) -> list[str]:
[p.strip() for p in split_commas(s)]
),
"enable_incomplete_feature": lambda s: [p.strip() for p in split_commas(s)],
"disable_error_code": lambda s: validate_codes([p.strip() for p in split_commas(s)]),
"enable_error_code": lambda s: validate_codes([p.strip() for p in split_commas(s)]),
"disable_error_code": lambda s: [p.strip() for p in split_commas(s)],
"enable_error_code": lambda s: [p.strip() for p in split_commas(s)],
"package_root": lambda s: [p.strip() for p in split_commas(s)],
"cache_dir": expand_path,
"python_executable": expand_path,
Expand All @@ -234,8 +223,8 @@ def split_commas(value: str) -> list[str]:
"always_false": try_split,
"untyped_calls_exclude": lambda s: validate_package_allow_list(try_split(s)),
"enable_incomplete_feature": try_split,
"disable_error_code": lambda s: validate_codes(try_split(s)),
"enable_error_code": lambda s: validate_codes(try_split(s)),
"disable_error_code": lambda s: try_split(s),
"enable_error_code": lambda s: try_split(s),
"package_root": try_split,
"exclude": str_or_array_as_list,
"packages": try_split,
Expand Down
9 changes: 8 additions & 1 deletion mypy/main.py
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Expand Up @@ -1456,9 +1456,16 @@ def set_strict_flags() -> None:
validate_package_allow_list(options.untyped_calls_exclude)
validate_package_allow_list(options.deprecated_calls_exclude)

options.process_error_codes(error_callback=parser.error)
options.process_incomplete_features(error_callback=parser.error, warning_callback=print)

def on_plugins_loaded() -> None:
# Processing error codes after plugins have loaded since plugins may
# register custom error codes that we don't know about until plugins
# have loaded.
options.process_error_codes(error_callback=parser.error)

options._on_plugins_loaded = on_plugins_loaded
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I don't like this pattern (callback that stores another callback). Instead you should simply use another way to create a blocker error, e.g. use raise CompileError(...) as a error_callback to process_error_codes() after the plugins are loaded.

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I made a refactor for this, but I don't have permission to commit to the PR.

@sigvef would you merge sigvef#1 or else grant me write permission on your fork?

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Nice! I added you as a collaborator on the fork, feel free to modify as you see fit!

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thank you-- committed callback refactor

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@belm0 belm0 Oct 3, 2025 •
edited
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@ilevkivskyi raising CompileError rather than calling parser.error() has a subtly different result, since only the latter will output CLI usage with the error. Are you sure about this change?

Test expectations fail as follows:

Expected:
  usage: mypy [-h] [-v] [-V] [more options; see below] (diff)
              [-m MODULE] [-p PACKAGE] [-c PROGRAM_TEXT] [files ...] (diff)
  mypy: error: Invalid error code(s): YOLO (diff)
  == Return code: 2
Actual:
  Invalid error code(s): YOLO (diff)
  == Return code: 2

Personally, I think parser.error() is the best for consistency with other parsing error cases. I wouldn't expect a different behavior only because a check needs to be deferred.

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It is fine (and probably even good) to not have the usage: ... part in this error. But I would add the mypy: error: prefix.

But also what you did is not what I wanted, the whole "double-callback" logic is pointless, you can simply call options.process_error_codes() directly in build.py.


# Compute absolute path for custom typeshed (if present).
if options.custom_typeshed_dir is not None:
options.abs_custom_typeshed_dir = os.path.abspath(options.custom_typeshed_dir)
Expand Down
2 changes: 2 additions & 0 deletions mypy/options.py
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Original file line number Diff line number Diff line change
Expand Up @@ -416,6 +416,8 @@ def __init__(self) -> None:
# preserving manual tweaks to generated C file)
self.mypyc_skip_c_generation = False

self._on_plugins_loaded: Callable[[], None] | None = None

def use_lowercase_names(self) -> bool:
warnings.warn(
"options.use_lowercase_names() is deprecated and will be removed in a future version",
Expand Down
35 changes: 24 additions & 11 deletions mypy/test/teststubtest.py
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Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,8 @@
from collections.abc import Iterator
from typing import Any, Callable

from pytest import raises

import mypy.stubtest
from mypy import build, nodes
from mypy.modulefinder import BuildSource
Expand Down Expand Up @@ -171,7 +173,12 @@ def build_helper(source: str) -> build.BuildResult:


def run_stubtest_with_stderr(
stub: str, runtime: str, options: list[str], config_file: str | None = None
stub: str,
runtime: str,
options: list[str],
config_file: str | None = None,
output: io.StringIO | None = None,
outerr: io.StringIO | None = None,
) -> tuple[str, str]:
with use_tmp_dir(TEST_MODULE_NAME) as tmp_dir:
with open("builtins.pyi", "w") as f:
Expand All @@ -188,8 +195,8 @@ def run_stubtest_with_stderr(
with open(f"{TEST_MODULE_NAME}_config.ini", "w") as f:
f.write(config_file)
options = options + ["--mypy-config-file", f"{TEST_MODULE_NAME}_config.ini"]
output = io.StringIO()
outerr = io.StringIO()
output = io.StringIO() if output is None else output
outerr = io.StringIO() if outerr is None else outerr
with contextlib.redirect_stdout(output), contextlib.redirect_stderr(outerr):
test_stubs(parse_options([TEST_MODULE_NAME] + options), use_builtins_fixtures=True)
filtered_output = remove_color_code(
Expand Down Expand Up @@ -2888,14 +2895,20 @@ def test_config_file_error_codes_invalid(self) -> None:
runtime = "temp = 5\n"
stub = "temp: int\n"
config_file = "[mypy]\ndisable_error_code = not-a-valid-name\n"
output, outerr = run_stubtest_with_stderr(
stub=stub, runtime=runtime, options=[], config_file=config_file
)
assert output == "Success: no issues found in 1 module\n"
assert outerr == (
"test_module_config.ini: [mypy]: disable_error_code: "
"Invalid error code(s): not-a-valid-name\n"
)
output = io.StringIO()
outerr = io.StringIO()
with raises(SystemExit):
run_stubtest_with_stderr(
stub=stub,
runtime=runtime,
options=[],
config_file=config_file,
output=output,
outerr=outerr,
)

assert output.getvalue() == "error: Invalid error code(s): not-a-valid-name\n"
assert outerr.getvalue() == ""

def test_config_file_wrong_incomplete_feature(self) -> None:
runtime = "x = 1\n"
Expand Down
32 changes: 32 additions & 0 deletions test-data/unit/check-plugin-error-codes.test
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@@ -0,0 +1,32 @@
[case testCustomErrorCodeFromPluginIsTargetable]
# flags: --config-file tmp/mypy.ini --show-error-codes

def main() -> None:
return
main() # E: Custom error [custom]

[file mypy.ini]
\[mypy]
plugins=<ROOT>/test-data/unit/plugins/custom_errorcode.py

[case testCustomErrorCodeCanBeDisabled]
# flags: --config-file tmp/mypy.ini --show-error-codes --disable-error-code=custom

def main() -> None:
return
main() # no output expected when disabled

[file mypy.ini]
\[mypy]
plugins=<ROOT>/test-data/unit/plugins/custom_errorcode.py

[case testCustomErrorCodeCanBeReenabled]
# flags: --config-file tmp/mypy.ini --show-error-codes --disable-error-code=custom --enable-error-code=custom

def main() -> None:
return
main() # E: Custom error [custom]

[file mypy.ini]
\[mypy]
plugins=<ROOT>/test-data/unit/plugins/custom_errorcode.py
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