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Work around concurrent import bug on free-threaded Python #22120

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Merged
ilevkivskyi merged 1 commit into from
Oct 6, 2026
+12 −6
Merged

Work around concurrent import bug on free-threaded Python #22120

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12 changes: 8 additions & 4 deletions mypy/parse.py
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Original file line number Diff line number Diff line change
Expand Up @@ -32,12 +32,14 @@ def parse(
parse contents from path `fnam` if `source` is `None`.
"""
if options.native_parser:
import mypy.nativeparse
# Use import from as workaround for cpython#149728 - accessing mypy.nativeparse
# after importing it may fail when this function is called concurrently.
from mypy import nativeparse

ignore_errors = options.ignore_errors or fnam in errors.ignored_files
# If errors are ignored, we can drop many function bodies to speed up type checking.
strip_function_bodies = ignore_errors and not options.preserve_asts
tree, _, _ = mypy.nativeparse.native_parse(
tree, _, _ = nativeparse.native_parse(
fnam, options, source, skip_function_bodies=strip_function_bodies
)
# Set is_stub based on file extension
Expand Down Expand Up @@ -120,9 +122,11 @@ def report_parse_error(error: ParseError, errors: Errors) -> None:

def parse_type_string(expr: StrExpr, options: Options) -> ProperType:
if options.native_parser:
import mypy.nativeparse
# Use a import from as workaround for cpython#149728 - accessing mypy.nativeparse
# after importing it may fail when this function is called concurrently.
from mypy import nativeparse

return mypy.nativeparse.native_parse_type_string(
return nativeparse.native_parse_type_string(
expr.value,
expr.line,
expr.column,
Expand Down
6 changes: 4 additions & 2 deletions mypy/test/testcmdline.py
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Original file line number Diff line number Diff line change
Expand Up @@ -13,7 +13,8 @@
import sys
import sysconfig

from mypy.test.config import PREFIX, test_temp_dir
import mypy
from mypy.test.config import test_temp_dir
from mypy.test.data import DataDrivenTestCase, DataSuite
from mypy.test.helpers import (
assert_string_arrays_equal,
Expand Down Expand Up @@ -72,7 +73,8 @@ def test_python_cmdline(testcase: DataDrivenTestCase, step: int) -> None:
env = os.environ.copy()
env.pop("COLUMNS", None)
extra_path = os.path.join(os.path.abspath(test_temp_dir), "pypath")
env["PYTHONPATH"] = PREFIX
# Use the same mypy installation as pytest, including the compiled wheel in CI.
env["PYTHONPATH"] = os.path.dirname(os.path.abspath(mypy.__path__[0]))
if os.path.isdir(extra_path):
env["PYTHONPATH"] += os.pathsep + extra_path
cwd = os.path.join(test_temp_dir, custom_cwd or "")
Expand Down
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