Excessive stack usage for clang-cl debug builds on W... | python/cpython

描述

test.test_call.TestRecursion.test_margin_is_sufficient fails on the AMD64 Windows Server 2025 Clang 3.14 buildbot.

The table lists safe_margin before it is multiplied, because 3.14 and main use different extra percents
https://github.com/python/cpython/blob/5b343636bae9b89cb5632ca07b01e1570e24653d/Lib/test/test_call.py#L1105-L1107
and _testinternalcapi.get_stack_margin(), which is actually just _PyOS_STACK_MARGIN_BYTES.

branch	compiler	build	safe_margin	_PyOS_STACK_MARGIN_BYTES
main	MSC v.1951	debug	20080	32768
main	clang-cl 22.1.3	debug	26032	32768
main	clang-cl 22.1.3	release	1200	16384
3.14	MSC v.1944	debug	23168	32768
3.14	clang-cl 22.1.3	debug	33920	32768
3.14	clang-cl 22.1.3	release	992	16384
3.14	clang-cl 22.1.3	debug with -Og	1536	32768

Using -Og drastically improves stack usage.

Excessive stack usage for clang-cl debug builds on Windows