wasip3: `sockets-tcp-connect::test_explicit_bind_addrinuse` does not get `AddressInUse` on second bind

[cataggar]

Summary

The upstream wasi-testsuite fixture wasm32-wasip3/sockets-tcp-connect (tests/rust/wasm32-wasip3/src/bin/sockets-tcp-connect.rs's test_explicit_bind_addrinuse) panics on wasmtime 44.0.1 (the first stable release with -Sp3 support). The fixture creates two sockets, binds the first to localhost:0, then asks the kernel for the assigned port and tries to bind a second socket to the same address, expecting ErrorCode::AddressInUse. wasmtime returns something other than Err(AddressInUse) and the matches! assertion panics.

Reproduction

# In a wasi-testsuite checkout at d8c30a7 with wasmtime 44.0.1 on PATH
cd tests/rust/wasm32-wasip3 && make build && cd -
wasmtime -Wcomponent-model-async -Sp3,inherit-network \
    tests/rust/testsuite/wasm32-wasip3/sockets-tcp-connect.wasm

Output (trimmed):

thread '<unnamed>' (1) panicked at src/bin/sockets-tcp-connect.rs:154:5:
assertion failed: matches!(result, Err(ErrorCode::AddressInUse))
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
Error: failed to run main module `…/sockets-tcp-connect.wasm`
…
   12:   0xbbf1 - sockets_tcp_connect…!sockets_tcp_connect…::test_explicit_bind_addrinuse::{closure#0}
…
    1: wasm trap: wasm `unreachable` instruction executed

The asserting code (tests/wasi-testsuite tests/rust/wasm32-wasip3/src/bin/sockets-tcp-connect.rs):

async fn test_explicit_bind_addrinuse(family: IpAddressFamily) {
    let listener = {
        let bind_address = IpSocketAddress::localhost(family, 0);
        let listener = TcpSocket::create(family).unwrap();
        listener.bind(bind_address).unwrap();   // bind to ephemeral port
        listener
    };

    let listener_address = listener.get_local_address().unwrap();  // ask the kernel for the port
    let client = TcpSocket::create(family).unwrap();

    let result = client.bind(listener_address);   // second bind to the same port
    assert!(matches!(result, Err(ErrorCode::AddressInUse)));   // panics on wasmtime 44.0.1
}

Cross-runtime parity

The same fixture passes on the WAMR-Zig WASIp3 host (40 / 40 wasm32-wasip3 fixtures pass, this one included), which suggests the upstream WIT contract is for bind to return Err(AddressInUse) when a second socket tries to bind to a port still held by another socket. wasmtime 44 either lets the second bind succeed (perhaps because SO_REUSEADDR is set on the second socket) or maps the kernel EADDRINUSE to a different ErrorCode variant.

Why this matters

This is one of four wasm32-wasip3 fixtures that fail on a stock wasmtime 44.0.1 install but pass on the WAMR-Zig host; tracked in cataggar/wamr#583 C1 (the cross-runtime parity gate). Filing here so the parity gate can mark it as a documented wasmtime-side delta until a wasmtime fix lands.

Environment

• wasmtime 44.0.1 (f302ebd6b 2026-04-30) — from curl https://wasmtime.dev/install.sh | bash -s -- --version v44.0.1
• wasi-testsuite wasi-testsuite-rust-runners-1.0.0 (40c1f7d) tests/rust/testsuite/wasm32-wasip3/sockets-tcp-connect.wasm
• Linux 6.x aarch64