Rust crate does not work with MSVC

[Rigidity]

The Rust crate blst does not compile when using MSVC as the compiler.

I'm not a C developer, but I did a little digging to figure out the root cause, and it appears that __STDC_VERSION__ was not defined. Following suggestions in the similar issue #103, I tried adding CFLAGS=/std:c11, but I got the same error.

I tried preprocessing a C file with these variables using C11 and it output the other condition that can cause the no_asm file to error, which is __STDC_NO_VLA__ being set to 1.

Apparently MSVC does not support Variable Length Arrays, which appears to be an optional extension. I did some research and it seems that they are generally not recommended for a variety of reasons, e.g. security, performance, and portability.

I'm using Windows 11 with Visual Studio 2022.

[dot-asm]

The Rust crate blst does not compile when using MSVC as the compiler.

This is a bit misleading, as the problem is not as general. It doesn't work specifically with 32-bit MSVC as the compiler.

If you have to build for 32-bit Windows (why?), add clang in the Visual Studio installer and execute cargo at x86 Tools Command Prompt. For reference, the prompt gives you 32-bit clang-cl on your %PATH%. This, 32-bit clang-cl on %PATH%, can be achieved by any other means.

[Rigidity]

I'm just trying to cargo run some code using BLS locally, not build an executable for 32 bit Windows. I'm on a 64 bit machine (Ryzen 5600X).

I'm using PowerShell inside of VSCode, which is a pretty typical development environment. Not sure why the shell I'm using plays any role in whether or not blst will compile?

[dot-asm]

I'm just trying to cargo run

Then your Rust installation is configured with i686-pc-windows-msvc as default target, instead of apparently expected x86_64-pc-windows-msvc. I naturally don't know how you installed and configured Rust on your computer, but you have the keyword now. Either ensure that x86_64 is the default, or pass --target=x86_64-pc-windows-msvc on cargo command line :-)

[Rigidity]

Weird, I'm on a 64-bit version of the OS on 64-bit hardware, so I'm really not sure why it decided to default to i686. Setting the target did indeed work.

Thanks for the help.