Add support for mingw targets

[seritools]

As requested in #23.

Any progress?

[seritools]

There have been no contributions on this, no.

[cher-nov]

I'm open to contributions there, but won't be implementing it myself.

Could you then please outline some kind of roadmap for this? I'd like to try my hand at making this happen, but would like to know where to start. The Rust codebase is a pretty non-obvious thing after all, y'know. :)

[seritools]

@cher-nov I am unfamiliar with the mingw targets and hacks necessary, but roughly it'll be

1. add targets for rust9x + mingw (see the relevant commit on the rust9x branch)
2. fix things until they build
3. fix things until they link
4. fix things until they run
5. fix things until they run correctly

Please note that I've also started work on a rust9x update/rebase for ~1.83, which changes a few things.

[cher-nov]

Please note that I've also started work on a rust9x update/rebase for ~1.83, which changes a few things.

This is great, endless thanks. One question: will the rustc itself continue to work on Windows 7 as host system, or rust9x project is only about target platforms? Because starting from 1.78.x the mainline became incompatible with it.
https://blog.rust-lang.org/2024/02/26/Windows-7.html

[seritools]

Rustc itself might work with rust9x, however that is not supported by me. In particular external deps of rustc, cargo, ... might use incompatible APIs and would need patching.

For the update I'm also aiming to use more conditional compilation so that my changes do not affect the normal pc-windows-msvc targets (at least as much, we'll see).

[ssokolow]

I suppose the question for Win7 host support boils down to checking how far that Tier 3 x86_64-win7-windows-msvc target is from getting its Host checkmark.

(Failing that, my own options for experimenting with targeting my retro-hobby PCs using Rust9x are either trying to run the prebuilt x86_64 offering in Wine or figuring out what I need to cross-compile from Linux. Unless I try swtching one of the "RasPi 4, but x86"-class mini-PCs I received as a hand-me-down back from Debian to the Windows 10 they came with, the newest Windows I've got is Win7.)

[Fenex]

This is great, endless thanks. One question: will the rustc itself continue to work on Windows 7 as host system, or rust9x project is only about target platforms? Because starting from 1.78.x the mainline became incompatible with it.

I have built Rust 1.91 (and some earlier) as host tools for windows 7 use rust-lang/rust source code without any changes, thus I believe we can compile modern version of rustc with host x86_64-win7-windows-msvc and targets *-rust9x-windows-msvc with no hard challenges.

Related PR that adds note to docs about success compiling host tools for windows 7: rust-lang#148362.

[Aerocatia]

FWIW, you can make win9x compatible executable using this mingw release https://github.com/redpanda-cpp/mingw-lite mingw32_686-msvcrt_win98-15.2.0-r7 and upstream i686-pc-windows-gnu provided it's nostd

So I assume on top of this you need to handle not using too-new win32 APIs in std as usual, and do something about using x87 floating point math instead of sse.