cannot be compiled on Windows

[chuacw]

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• This is not a support question.

Description of bug

Polkadot SDK cannot be compiled on Windows

Steps to reproduce

git clone https://github.com/paritytech/polkadot-sdk.git
cd polkadot-sdk
cargo build --release

error[E0433]: failed to resolve: could not find `sys` in `nix`
  --> polkadot\node\core\pvf\common\src\worker\mod.rs:27:25
   |
27 | use nix::{errno::Errno, sys::resource::Usage};
   |                         ^^^ could not find `sys` in `nix`
error[E0432]: unresolved import `nix::errno`
  --> polkadot\node\core\pvf\common\src\worker\mod.rs:27:11
   |
27 | use nix::{errno::Errno, sys::resource::Usage};
   |           ^^^^^ could not find `errno` in `nix`

error[E0433]: failed to resolve: could not find `unix` in `os`
  --> polkadot\node\core\pvf\common\src\worker\mod.rs:35:3
   |
35 |         unix::net::UnixStream,
   |         ^^^^ could not find `unix` in `os`
error[E0432]: unresolved import `std::os::fd`
   --> polkadot\node\core\pvf\common\src\worker\mod.rs:34:3
    |
34  |         fd::{AsRawFd, FromRawFd, RawFd},
    |         ^^ could not find `fd` in `os`
error[E0425]: cannot find function `pipe2` in crate `libc`
   --> polkadot\node\core\pvf\common\src\worker\mod.rs:200:27
    |
200 |     let res = unsafe { libc::pipe2(fds.as_mut_ptr(), libc::O_CLOEXEC) };
    |                              ^^^^^ help: a function with a similar name exists: `pipe`

error[E0425]: cannot find value `O_CLOEXEC` in crate `libc`
   --> polkadot\node\core\pvf\common\src\worker\mod.rs:200:57
    |
200 |     let res = unsafe { libc::pipe2(fds.as_mut_ptr(), libc::O_CLOEXEC) };
    |                                                            ^^^^^^^^^ not found in `libc`

error[E0425]: cannot find function `getppid` in crate `libc`
   --> polkadot\node\core\pvf\common\src\worker\mod.rs:533:20
    |
533 |         let ppid = libc::getppid();
    |                          ^^^^^^^ help: a function with a similar name exists: `getpid`
    |
491 |     pub fn getpid() -> ::c_int;
    |     -------------------------- similarly named function `getpid` defined here

error[E0425]: cannot find function `kill` in crate `libc`
   --> polkadot\node\core\pvf\common\src\worker\mod.rs:535:10
    |
535 |             libc::kill(ppid, libc::SIGTERM);
    |                   ^^^^ not found in `libc`

[bkchr]

We don't officially support Windows. I know that some people are using the Linux subsystem to run Substrate based chains.

[chuacw]

"We don't officially support Windows."

Not supporting it doesn't mean it shouldn't compile.
AFAICT, the issue is functions which are not implemented in the used crate, libc.

[nazar-pc]

Not supporting it doesn't mean it shouldn't compile.

I guess it was an invitation to contribute corresponding fix 🙂

Substrate (at least up to 1.13) does successfully compile and run on Windows (we also run CI on Windows), but we (at Subspace) do not use Polkadot-specific crates, so you might want to contribute corresponding changes if you need to run it on Windows natively for whatever reason.

[bkchr]

I guess it was an invitation to contribute corresponding fix 🙂

Exactly ;) I don't have a Windows machine to compile and fix these issues. So, if you have one, I will happily approve any pr.

[chuacw]

The issue is with the libc crate used. I'm closing this and have started investigating and contributing fixes to libc as a result.

[bkchr]

I don't think that the issue is in libc and more in our codebase that we don't feature gated the usage correctly.

[chuacw]

"don't have a Windows machine to compile and fix these issues. "

You don't need a Windows machine to compile for the Windows target.

rustc is a cross-compiler.

[nazar-pc]

rustc is a cross-compiler.

If you actually try it in practice you'll notice it is not as simple as having a compiler capable of cross-compilation. I wish it was though.

[chuacw]

@bkchr
"don't think that the issue is in libc"

I found libc::kill doesn't exist on Windows, so I've created a PR for it.