[wanxiankai]

Description

Fixes #3157.

Parser failures currently reach the CLI as a string, so the report prefix separates the file path from the line and column (cannot format path: Cannot parse: line:column). This prevents editors and problem matchers from recognizing a standard source location.

This change keeps structured context, line, column, and diagnostic details on InvalidInput while preserving its existing string representation for API consumers such as blackd. CLI reports now render parser failures as error: cannot parse: path:line:column, while non-parser failures retain the existing cannot format output. The structured attributes are also covered by a pickle round trip because multi-file formatting passes exceptions back from worker processes.

Checklist - did you ...

• Implement any code style changes under the --preview style, following the stability policy? (No code style change.)
• Add an entry in CHANGES.md if necessary?
• Add / update tests if necessary?
• Add new / update outdated documentation? (No documentation change is needed for this error-output fix.)

Test results

• 471 passed, 3 skipped, 8 subtests passed
• pre-commit: isort, flake8, mypy, end-of-file, trailing-whitespace, and changelog checks passed

[github-actions]

diff-shades results comparing this PR (cd56ef3) to main (928f503):

--preview style: no changes

--stable style: no changes

---

What is this? | Workflow run | diff-shades documentation

[cobaltt7]

Please check the failing test!

[wanxiankai]

Thanks for the heads-up! I found the failing job was mypyc wheels cp310-manylinux_x86_64: the compiled wheel was losing the InvalidInput location/details attributes after the pickle round trip used by the worker path.

I pushed 3f87374, which initializes those fields through InvalidInput.__init__() and preserves them through __reduce__() so the mypyc-compiled package keeps lineno, column, context, and details after unpickling.

Local checks run:

• .venv/bin/python -m pytest tests/test_black.py::BlackTestCase::test_lib2to3_parse tests/test_black.py::test_invalid_input_error_includes_path_location tests/test_black.py::TestCaching::test_failed_formatting_does_not_get_cached -n auto (3 passed)
• .venv/bin/python -m mypy src/black/parsing.py src/black/report.py
• git diff --check

[cobaltt7]

Please also update the sample errors in the docs (the_basics.md, you can search for "Cannot parse"). Thank you!

[wanxiankai]

Thanks for the review! I pushed 4515b2a addressing the requested changes:

• Updated the sample parse errors in docs/usage_and_configuration/the_basics.md.
• Changed Report.failed() to accept exceptions only and updated the report tests to pass Exception("boom") instead of strings.
• Moved the lowercase parser context and the leading details newline into parsing.py.
• Replaced InvalidInput.from_syntax_error() / reduce with direct constructor usage. The constructor now passes the structured fields through ValueError so pickle preserves them, while str keeps the displayed message clean.
• Kept the ParseError details construction formatted across multiple lines.

Checks run:

• .venv/bin/python -m pytest tests/test_black.py::test_invalid_input_error_includes_path_location tests/test_black.py::BlackTestCase::test_report_verbose tests/test_black.py::BlackTestCase::test_report_quiet tests/test_black.py::BlackTestCase::test_report_normal tests/test_black.py::BlackTestCase::test_lib2to3_parse tests/test_black.py::BlackTestCase::test_format_file_contents tests/test_black.py::BlackTestCase::test_for_handled_unexpected_eof_error tests/test_format.py::test_patma_invalid tests/test_blackd.py::BlackDTestCase::test_blackd_request_syntax_error -q (9 passed)
• .venv/bin/python -m mypy src/black/parsing.py src/black/report.py
• .venv/bin/pre-commit run flake8 --files src/black/parsing.py src/black/report.py tests/test_black.py tests/test_format.py tests/test_blackd.py
• .venv/bin/python -m black --check src/black/parsing.py src/black/report.py tests/test_black.py tests/test_format.py tests/test_blackd.py
• git diff --check

[cobaltt7]

Thank you!