add support for static override on Windows

[Noxybot]

No description provided.

[daanx]

I don't think this can really work? Nowadays, one should link with the universal C runtime library which is a DLL so there is no way to statically override the allocator (unless I guess we link to a static CRT -- is that the use case that you envision?).

[Noxybot]

Nowadays, one should link with the universal C runtime library which is a DLL

There are multiple reasons why one would want to link CRT statically.

1. Security (harder to do DLL injection)
2. Perf (sometime not having to load DLL might make your process to start up faster)
3. Consistency
4. Not having to use mimalloc-redirrect.dll and avoid shipping arm64 version for Windows (this is actually a big one. Static overrides would work for x86 binaries on Arm64EC)

Having said this, I can also confirm that we using this patch internally for our app that links CRT statically and it works fine / robust :)

[Noxybot]

@microsoft-github-policy-service agree company="Roblox"

[mat-gas]

Hi,
what's the status on this PR?
We also link the CRT statically and would be very much interested in this

[daanx]

Hi @Noxybot -- apologies for the late merge! it is merged now though. In my testing though it only worked well if always linking with the static C runtime /MT even in debug mode. If I link with /MTd I get duplicate symbol errors for _expand ? I will test a bit more before updating the documentation -- but it seems to work and I can see the use cases for those that are aware of the implications of statically linking the C runtime.
Thanks so much, hope you are doing well. Best, Daan