add wasm32-wasip2 support

This adds support for the new `wasm32-wasip2` target platform, which includes
more extensive support for sockets than `wasm32-wasip1` (formerly known as
`wasm32-wasi`).

The bulk of the changes are in tokio-rs/mio#1836.  This
patch just tweaks a few `cfg` directives to indicate `wasm32-wasip2`'s
additional capabilities.

In the future, we could consider adding support for `ToSocketAddrs`.  WASIp2
natively supports asynchronous DNS lookups and is single threaded, whereas Tokio
currently assumes DNS lookups are blocking and require multithreading to emulate
async lookups.  A WASIp2-specific implementation could do the lookup directly
without multithreading.

I've tested this end-to-end using https://github.com/dicej/wasi-sockets-tests,
which includes smoke tests for `mio`, `tokio`, `tokio-postgres`, etc.  I'd also
be happy to add tests to this repo if appropriate; it would require adding a
dev-dependency on e.g. `wasmtime` to actually run the test cases.

Signed-off-by: Joel Dice <[email protected]>

Author: dicej

tokio/Cargo.toml

@@ -27,18 +27,18 @@ default = []
 
 # enable everything
 full = [
-  "fs",
-  "io-util",
-  "io-std",
-  "macros",
-  "net",
-  "parking_lot",
-  "process",
-  "rt",
-  "rt-multi-thread",
-  "signal",
-  "sync",
-  "time",
+    "fs",
+    "io-util",
+    "io-std",
+    "macros",
+    "net",
+    "parking_lot",
+    "process",
+    "rt",
+    "rt-multi-thread",
+    "signal",
+    "sync",
+    "time",
 ]
 
 fs = []
@@ -47,39 +47,39 @@ io-util = ["bytes"]
 io-std = []
 macros = ["tokio-macros"]
 net = [
-  "libc",
-  "mio/os-poll",
-  "mio/os-ext",
-  "mio/net",
-  "socket2",
-  "windows-sys/Win32_Foundation",
-  "windows-sys/Win32_Security",
-  "windows-sys/Win32_Storage_FileSystem",
-  "windows-sys/Win32_System_Pipes",
-  "windows-sys/Win32_System_SystemServices",
+    "libc",
+    "mio/os-poll",
+    "mio/os-ext",
+    "mio/net",
+    "socket2",
+    "windows-sys/Win32_Foundation",
+    "windows-sys/Win32_Security",
+    "windows-sys/Win32_Storage_FileSystem",
+    "windows-sys/Win32_System_Pipes",
+    "windows-sys/Win32_System_SystemServices",
 ]
 process = [
-  "bytes",
-  "libc",
-  "mio/os-poll",
-  "mio/os-ext",
-  "mio/net",
-  "signal-hook-registry",
-  "windows-sys/Win32_Foundation",
-  "windows-sys/Win32_System_Threading",
-  "windows-sys/Win32_System_WindowsProgramming",
+    "bytes",
+    "libc",
+    "mio/os-poll",
+    "mio/os-ext",
+    "mio/net",
+    "signal-hook-registry",
+    "windows-sys/Win32_Foundation",
+    "windows-sys/Win32_System_Threading",
+    "windows-sys/Win32_System_WindowsProgramming",
 ]
 # Includes basic task execution capabilities
 rt = []
 rt-multi-thread = ["rt"]
 signal = [
-  "libc",
-  "mio/os-poll",
-  "mio/net",
-  "mio/os-ext",
-  "signal-hook-registry",
-  "windows-sys/Win32_Foundation",
-  "windows-sys/Win32_System_Console",
+    "libc",
+    "mio/os-poll",
+    "mio/net",
+    "mio/os-ext",
+    "signal-hook-registry",
+    "windows-sys/Win32_Foundation",
+    "windows-sys/Win32_System_Console",
 ]
 sync = []
 test-util = ["rt", "sync", "time"]
@@ -92,7 +92,8 @@ pin-project-lite = "0.2.11"
 
 # Everything else is optional...
 bytes = { version = "1.2.1", optional = true }
-mio = { version = "1.0.1", optional = true, default-features = false }
+# TODO dicej: switch to upstream once WASIp2 support is merged:
+mio = { git = "https://github.com/dicej/mio", branch = "wasip2", optional = true, default-features = false }
 parking_lot = { version = "0.12.0", optional = true }
 
 [target.'cfg(not(target_family = "wasm"))'.dependencies]
@@ -101,7 +102,9 @@ socket2 = { version = "0.5.5", optional = true, features = ["all"] }
 # Currently unstable. The API exposed by these features may be broken at any time.
 # Requires `--cfg tokio_unstable` to enable.
 [target.'cfg(tokio_unstable)'.dependencies]
-tracing = { version = "0.1.29", default-features = false, features = ["std"], optional = true } # Not in full
+tracing = { version = "0.1.29", default-features = false, features = [
+    "std",
+], optional = true } # Not in full
 
 # Currently unstable. The API exposed by these features may be broken at any time.
 # Requires `--cfg tokio_unstable` to enable.
@@ -114,18 +117,19 @@ signal-hook-registry = { version = "1.1.1", optional = true }
 
 [target.'cfg(unix)'.dev-dependencies]
 libc = { version = "0.2.168" }
-nix = { version = "0.29.0", default-features = false, features = ["aio", "fs", "socket"] }
+nix = { version = "0.29.0", default-features = false, features = [
+    "aio",
+    "fs",
+    "socket",
+] }
 
 [target.'cfg(windows)'.dependencies.windows-sys]
 version = "0.52"
 optional = true
 
 [target.'cfg(windows)'.dev-dependencies.windows-sys]
 version = "0.52"
-features = [
-  "Win32_Foundation",
-  "Win32_Security_Authorization",
-]
+features = ["Win32_Foundation", "Win32_Security_Authorization"]
 
 [dev-dependencies]
 tokio-test = { version = "0.4.0", path = "../tokio-test" }
@@ -157,7 +161,14 @@ tracing-mock = "= 0.1.0-beta.1"
 [package.metadata.docs.rs]
 all-features = true
 # enable unstable features in the documentation
-rustdoc-args = ["--cfg", "docsrs", "--cfg", "tokio_unstable", "--cfg", "tokio_taskdump"]
+rustdoc-args = [
+    "--cfg",
+    "docsrs",
+    "--cfg",
+    "tokio_unstable",
+    "--cfg",
+    "tokio_taskdump",
+]
 # it's necessary to _also_ pass `--cfg tokio_unstable` and `--cfg tokio_taskdump`
 # to rustc, or else dependencies will not be enabled, and the docs build will fail.
 rustc-args = ["--cfg", "tokio_unstable", "--cfg", "tokio_taskdump"]
@@ -169,9 +180,9 @@ features = ["full", "test-util"]
 # The following are types that are allowed to be exposed in Tokio's public API.
 # The standard library is allowed by default.
 allowed_external_types = [
-  "bytes::buf::buf_impl::Buf",
-  "bytes::buf::buf_mut::BufMut",
-  "tokio_macros::*",
+    "bytes::buf::buf_impl::Buf",
+    "bytes::buf::buf_mut::BufMut",
+    "tokio_macros::*",
 ]
 
 [lints]

tokio/src/macros/cfg.rs

@@ -594,6 +594,15 @@ macro_rules! cfg_not_wasi {
     }
 }
 
+macro_rules! cfg_not_wasip1 {
+    ($($item:item)*) => {
+        $(
+            #[cfg(any(not(target_os = "wasi"), target_env = "p2"))]
+            $item
+        )*
+    }
+}
+
 macro_rules! cfg_is_wasm_not_wasi {
     ($($item:item)*) => {
         $(

tokio/src/net/mod.rs

@@ -29,7 +29,7 @@
 //! [`AsyncFd`]: crate::io::unix::AsyncFd
 
 mod addr;
-cfg_not_wasi! {
+cfg_not_wasip1! {
     #[cfg(feature = "net")]
     pub(crate) use addr::to_socket_addrs;
 }

tokio/src/net/tcp/stream.rs

@@ -1,7 +1,10 @@
 cfg_not_wasi! {
+    use std::time::Duration;
+}
+
+cfg_not_wasip1! {
     use crate::net::{to_socket_addrs, ToSocketAddrs};
     use std::future::poll_fn;
-    use std::time::Duration;
 }
 
 use crate::io::{AsyncRead, AsyncWrite, Interest, PollEvented, ReadBuf, Ready};
@@ -72,7 +75,7 @@ cfg_net! {
 }
 
 impl TcpStream {
-    cfg_not_wasi! {
+    cfg_not_wasip1! {
         /// Opens a TCP connection to a remote host.
         ///
         /// `addr` is an address of the remote host. Anything which implements the