New submission from STINNER Victor <vstin...@python.org>:

The Visual Studio project of Python, PCBuild\ directory, disables compiler 
optimizations when Python is built in debug mode. It seems to be the default in 
Visual Studio.

Disabling compiler optimizations cause two kinds of issues:

* It increases the stack memory: tests using a deep call stack are more likely 
to crash (test_pickle, test_marshal, test_exceptions).

* Running the Python test suite take 19 min 41 sec instead of 12 min 19 sec on 
Windows x64: 1.6x slower. Because of that, we cannot use a debug build in the 
GitHub Action pre-commit CI, and we miss bugs which are catched "too late", in 
Windows buildbots. See my latest attempt to use a debug build in GitHub 
Actions: https://github.com/python/cpython/pull/24914

Example of test_marshal:

        # The max stack depth should match the value in Python/marshal.c.
        # BUG: https://bugs.python.org/issue33720
        # Windows always limits the maximum depth on release and debug builds
        #if os.name == 'nt' and hasattr(sys, 'gettotalrefcount'):
        if os.name == 'nt':
            MAX_MARSHAL_STACK_DEPTH = 1000
        else:
            MAX_MARSHAL_STACK_DEPTH = 2000

I propose to only change the compiler options for the pythoncore project which 
builds most important files for the Python "core". See attached PR.

----------
components: Windows
messages: 401141
nosy: paul.moore, steve.dower, tim.golden, vstinner, zach.ware
priority: normal
severity: normal
status: open
title: Windows: enable compiler optimizations when building Python in debug mode
versions: Python 3.11

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<https://bugs.python.org/issue45115>
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