fix: macOS/Windows build for ttrpc TAP cfg gates

Revert TapHandle to cfg(unix) since it's just a data type carrying an
OwnedFd. Use unconditional Backend::Tap match arm with cfg blocks inside
the body to avoid all-diverging-arms warnings on macOS.

Author: jstarks

openvmm/openvmm_entry/src/ttrpc/mod.rs

@@ -704,6 +704,10 @@ impl VmService {
     }
 }
 
+#[cfg_attr(
+    not(any(windows, target_os = "linux")),
+    allow(unreachable_code, unused_variables)
+)]
 fn parse_nic_config(
     nic: vmservice::NicConfig,
 ) -> anyhow::Result<(DeviceVtl, Resource<VmbusDeviceHandleKind>)> {
@@ -724,10 +728,17 @@ fn parse_nic_config(
             },
         }
         .into_resource(),
-        #[cfg(target_os = "linux")]
         Backend::Tap(tap) => {
-            let fd = net_tap::tap::open_tap(&tap.name).context("failed to open TAP device")?;
-            net_backend_resources::tap::TapHandle { fd }.into_resource()
+            #[cfg(target_os = "linux")]
+            {
+                let fd = net_tap::tap::open_tap(&tap.name).context("failed to open TAP device")?;
+                net_backend_resources::tap::TapHandle { fd }.into_resource()
+            }
+            #[cfg(not(target_os = "linux"))]
+            {
+                let _ = tap;
+                anyhow::bail!("TAP backend is only supported on Linux")
+            }
         }
         _ => anyhow::bail!("unsupported backend"),
     };

petri/burette/src/tests/network.rs

@@ -408,13 +408,18 @@ impl NetworkTest {
         std::thread::sleep(std::time::Duration::from_millis(500));
 
         // Run guest iperf3 client.
-        run_guest_iperf3_client(&state.agent, host_ip, port, &mode, metric_name, state.use_chroot)
-            .await?;
+        run_guest_iperf3_client(
+            &state.agent,
+            host_ip,
+            port,
+            &mode,
+            metric_name,
+            state.use_chroot,
+        )
+        .await?;
 
         // Collect JSON from the helper.
-        let json = json_future
-            .await
-            .context("iperf3 helper RPC failed")?;
+        let json = json_future.await.context("iperf3 helper RPC failed")?;
 
         if !json.is_empty() {
             tracing::debug!(metric = metric_name, json = %json, "raw iperf3 output");
@@ -494,8 +499,7 @@ mod tap {
     /// Add a VMBus synthnic backed by a TAP fd to the VM config.
     fn add_tap_nic(config: &mut openvmm_defs::config::Config, tap_fd: std::os::fd::OwnedFd) {
         let endpoint = net_backend_resources::tap::TapHandle { fd: tap_fd }.into_resource();
-        const TAP_NETVSP_INSTANCE: guid::Guid =
-            guid::guid!("a1b2c3d4-e5f6-7890-abcd-ef1234567890");
+        const TAP_NETVSP_INSTANCE: guid::Guid = guid::guid!("a1b2c3d4-e5f6-7890-abcd-ef1234567890");
 
         config.vmbus_devices.push((
             DeviceVtl::Vtl0,
@@ -510,10 +514,7 @@ mod tap {
     }
 
     /// Add a virtio-net NIC backed by a TAP fd to the VM config (PCIe).
-    fn add_virtio_tap_nic(
-        config: &mut openvmm_defs::config::Config,
-        tap_fd: std::os::fd::OwnedFd,
-    ) {
+    fn add_virtio_tap_nic(config: &mut openvmm_defs::config::Config, tap_fd: std::os::fd::OwnedFd) {
         let endpoint = net_backend_resources::tap::TapHandle { fd: tap_fd }.into_resource();
 
         config.pcie_devices.push(PcieDeviceConfig {

vm/devices/net/net_backend_resources/src/lib.rs

@@ -72,7 +72,7 @@ pub mod dio {
 }
 
 /// Linux TAP backend.
-#[cfg(target_os = "linux")]
+#[cfg(unix)]
 pub mod tap {
     use mesh::MeshPayload;
     use vm_resource::ResourceId;