Port Status — CPython 3.11.16 to Windows 98 SE

Date: 2026-08-17 Baseline: CPython v3.11.16 Compiler: MSVC 6.0 (cl.exe 12.00.8804), from external MSVC600 Host test environment: Linux + Wine

Verified

CPython source checkout is at the requested v3.11.16 baseline.
The MSVC600 tool bundle is present locally and its VC98/bin/VCVARS32.BAT environment script runs under Wine.

MSVC6 reports:

Microsoft (R) 32-bit C/C++ Optimizing Compiler Version 12.00.8804 for 80x86

A direct compile probe reaches CPython 3.11 headers. The first unmodified probe fails before linking, proving the compiler is being invoked against the intended baseline.
A project-local compatibility inttypes.h has been added under compat/msvc600/ as the first isolated shim. It is not yet wired into CPython source or declared sufficient for the port.

Current first-blocker evidence

The probe command was equivalent to:

cl /nologo /I compat/msvc600 /I cpython/Include /I cpython/PC \
   /c cpython/Programs/python.c

The next errors include:

Py_uintptr_t / Py_intptr_t configuration failures in Include/pyport.h
unsupported C inline syntax in Include/object.h and other public headers
unsupported __declspec(deprecated) annotations
additional C99/C99-era declarations and compatibility assumptions

Before the compatibility header was supplied, VC6 stopped immediately on the missing inttypes.h include. The isolated header resolved only that first missing-header error; it is intentionally not presented as a complete fix.

Larger blockers to plan for

Build-system mismatch: CPython 3.11's Windows build expects Visual Studio 2017-era MSBuild/vcxproj tooling. VC6 cannot consume the build as-is. A dedicated minimal VC6 makefile/project set is required.
Compiler language gap: CPython 3.11 source and headers use C99-era and later MSVC features that VC6 does not implement. Compatibility macros and carefully scoped source backports are required.
Win9x API gap: CPython 3.11's Windows layer assumes NT-family Unicode, synchronization, process, filesystem, and networking APIs. Windows 98 has no wide-character file APIs and lacks multiple newer kernel APIs.
Runtime/library gap: SSL, SQLite, ctypes, multiprocessing, asyncio, Unicode filesystem behavior, and parts of subprocess will need explicit feature gates or Win9x-specific implementations.
Validation gap: final success requires booting the built executable on Windows 98 SE; Wine compilation alone is not proof of Win9x runtime compatibility.

Recommended next implementation slice

Do not attempt the complete CPython solution yet. First create a minimal VC6 build target for pythoncore plus Programs/python.c, then make the public headers compile under VC6 through a clearly isolated compatibility layer. Keep all changes small and testable. After the core links, address the Win9x API surface one subsystem at a time.

Scope boundary

This project does not vendor the 223 MB MSVC600 bundle into a distributable repository. It records the external tool as a local build prerequisite. No Microsoft compiler binaries or runtime files should be committed or published.

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