[GGRei]

Summary

Complete the manual Windows CRT prelude with the missing declarations for _wfreopen, _fseeki64, fgetpos, _wpopen, and _pclose.

Add Windows TinyCC runtime regressions covering:

• os.File.reopen
• the _wpopen / _pclose command-pipe lifecycle
• the existing embed_issue_12035 full generated-C path

Additional note

Strict Windows TCC validation also exposed a missing freopen_s declaration in the generated C prelude. This PR now includes the correct declaration and a regression test covering Windows GUI builds with -subsystem windows.

The existing declarations and behavior remain unchanged. The complete targeted Windows TCC smoke passed.

Cause

V's generated C uses a manual CRT prelude. Some Windows CRT functions used by the compiled modules were not visible to TinyCC through that prelude, causing implicit-function-declaration failures with -no-retry-compilation.

The symbols already exist in the Windows CRT and tccbin exports. This was a generated-C declaration visibility issue, not a pkg-config or linker-library issue.

Validation

Native Windows TinyCC smoke passed with no fallback:

• File.reopen compile, link, and runtime
• _wpopen / _pclose runtime
• embed_issue_12035 -prod -no-skip-unused
• complete coutput_test.v
• direct generated-C collector with zero implicit symbols

[GGRei]

Ready Alex Thanks!

PS: The Windows TCC job now gets much further. It still fails on missing strict declarations for CancelIoEx and freopen_s in the Windows amd64 TCC/V path. I will address those separately later.

[GGRei]

@codex review

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. Hooray!

Reviewed commit: e0b816e324

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