Consolidate some duplicate code in the sys modules.

[ehuss]

This consolidates some modules which were duplicated throughout the sys module. The intent is to make it easier to update and maintain this code. This mainly affects the wasi, sgx, and "unsupported" targets.

I explicitly skipped hermit, cloudabi, and vxworks. These tier-3 targets have copied large sections of the sys tree. I don't think they should have, but I don't want to put effort into changing them. It also doesn't help that there aren't any scripts or instructions for building them.

There are still sections of duplicate code here and there, but this PR covers the easy parts where entire modules are the same.

[rust-highfive]

r? @sfackler

(rust_highfive has picked a reviewer for you, use r? to override)

[ehuss]

cc @alexcrichton modifies wasi
cc @jethrogb modifies sgx

[jethrogb]

Thanks for the ping! LGTM modulo one comment. Also I assume if we do ever implement (parts) of these APIs we can just (partially) undo this change.

[jethrogb]

It seems a little strange to pull the IoSlice types from somewhere with “unsupported” in the name, as these types are actually used and supported on this target.

[ehuss]

Yea, good point. I can't think of a good place to put this module, since there isn't a location for "basic implementation that is not Unix". Would it make sense to add a sys::basic module that contained code like this? The only other "functional" code in the unsupported tree is:

• cmath.rs (basic definitions from compiler-builtins)
• common.rs strlen (very simple pure-rust C-strlen implementation)

[bors]

☔ The latest upstream changes (presumably #75971) made this pull request unmergeable. Please resolve the merge conflicts.

[ehuss]

@sfackler do you think you'll be able to review this?

[Dylan-DPC-zz]

merging this given that there was one approval even though not from the reviewer.

@bors r=sfackler

[bors]

📌 Commit 90b941d05147a81a8236365bcf380e01f20a3ed1 has been approved by sfackler

[bors]

⌛ Testing commit 90b941d05147a81a8236365bcf380e01f20a3ed1 with merge 7ee2bd15797d69501f36b94f083f18031d11893c...

[bors]

💔 Test failed - checks-actions

[jethrogb]

error: couldn't read library/std/src/sys/wasm/../unsupported/path.rs: No such file or directory (os error 2)
--> library/std/src/sys/wasm/mod.rs:31:1
|
31 | pub mod path;
| ^^^^^^^^^^^^^

[ehuss]

Not sure how I missed that attribute, I thought I had tested it.

@bors r=alexcrichton

[bors]

📌 Commit 25cca07 has been approved by alexcrichton