Make MMIO buildable for WASI (exclude ShellCommand.swift)

[MaxDesiatov]

Neither Dispatch nor Process are available on WASI. To make this module buildable, code in ShellCommand.swift needs to be excluded.

Checklist

• I've followed the code style of the rest of the project
• I've read the Contribution Guidelines

- [ ] I've updated the documentation if necessary
- [ ] I've added at least one test that validates that my change is working, if appropriate

[rauhul]

Aside from the abysmal issue of dispatch on linux crashing all the time, I'd like to make sure we have ci for any new platforms this repo intends to support, what might that look like for wasi?

[MaxDesiatov]

Since there's no 1st-party Swift SDK for WASI, we can't set up a CI for it and support for WASI can only be tested locally.

[rauhul]

Since there's no 1st-party Swift SDK for WASI, we can't set up a CI for it and support for WASI can only be tested locally.

how does one test it locally?

[MaxDesiatov]

The only way I know of is to get a Swift SDK from SwiftWasm and build with that.

[rauhul]

What SDK content do you expect would be need? the primary MMIO library has no libc dependency, unless I accidentally re-introduced one.

[MaxDesiatov]

IIUC no Swift SDK for WASI content is needed for MMIO per se. But packages built for WASI depending on MMIO would have to build MMIO for WASI too, because currently there can be only one target platform for the whole build graph in SwiftPM.

[rauhul]

Since sh is only used in test code I wonder if theres another option that splits MMIOUtils into two modules?

[rauhul]

@MaxDesiatov is this still needed? I've moved ShellCommand out of MMIOUtilities.

[MaxDesiatov]

Even if it were moved out to a separate module, swift build invocation would still fail with this code not conditionally excluded.

[rauhul]

This code is only in test targets that doesn't run on the embedded targets anyways now