Compiler warnings in building Python 3.9 on Windows

[serhiy-storchaka]

BPO	43499
Nosy	@vstinner, @serhiy-storchaka, @ammaraskar
PRs	[3.9] bpo-43499: Silence compiler warnings about using legacy C API on Windows #24873 Restrict co_code to be under INT_MAX in codeobject #20628 bpo-39943: Fix MSVC warnings in sre extension #20508 bpo-41654: Fix compiler warning in MemoryError_dealloc() #22387 [3.9] bpo-43499: Restrict co_code to be under INT_MAX in codeobject (GH-20628) #24896

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2021-03-17.18:27:30.933>
created_at = <Date 2021-03-15.12:12:03.640>
labels = ['extension-modules', 'interpreter-core', '3.9']
title = 'Compiler warnings in building Python 3.9 on Windows'
updated_at = <Date 2021-03-17.18:27:30.932>
user = 'https://github.com/serhiy-storchaka'

bugs.python.org fields:

activity = <Date 2021-03-17.18:27:30.932>
actor = 'serhiy.storchaka'
assignee = 'none'
closed = True
closed_date = <Date 2021-03-17.18:27:30.933>
closer = 'serhiy.storchaka'
components = ['Extension Modules', 'Interpreter Core']
creation = <Date 2021-03-15.12:12:03.640>
creator = 'serhiy.storchaka'
dependencies = []
files = []
hgrepos = []
issue_num = 43499
keywords = ['patch']
message_count = 6.0
messages = ['388731', '388821', '388855', '388856', '388954', '388955']
nosy_count = 3.0
nosy_names = ['vstinner', 'serhiy.storchaka', 'ammar2']
pr_nums = ['24873', '20628', '20508', '22387', '24896']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue43499'
versions = ['Python 3.9']

[serhiy-storchaka]

Currently building Python 3.9 on Windows produce many compiler warnings. 3.8 and master are clean.

• Warnings in the _sre module caused by the bug in MSVC (complains about automatic conversion of "void **" to "const void *"). Fixed by backporting PR20508.

• Warnings in many files related to using legacy C API (e.g. PyUnicode_AsUnicode) in Windows specific code.

• ..\Objects\exceptions.c(2313): warning C4098: 'MemoryError_dealloc': 'void' function returning a value

• ..\Objects\frameobject.c(400): warning C4267: 'initializing': conversion from 'size_t' to 'int', possible loss of data

The last two may be hidden bugs.

[serhiy-storchaka]

New changeset 651fc30 by Serhiy Storchaka in branch '3.9':
bpo-43499: Silence compiler warnings about using legacy C API on Windows (GH-24873)
651fc30

[serhiy-storchaka]

Ammar Askar, do you mind to backport PR 20628 to 3.9? It is the only warning left, and it seems there is a potential bug.

[ammaraskar]

Sure thing, I'll work on the backport.

[serhiy-storchaka]

New changeset db73376 by Ammar Askar in branch '3.9':
[3.9] bpo-43499: Restrict co_code to be under INT_MAX in codeobject (GH-20628) (GH-24896)
db73376

[serhiy-storchaka]

Thank you Ammar.