style: Silence Clippy's complaint on nightly toolchain

Clippy, with the nightly toolchain, complains as follows:

     error: this `if` statement can be collapsed
      --> cli/bin/completions.rs:75:17
       |
    75 | /                 if let Some((arg_side, value_side)) = word.split_once("=") {
    76 | |                     if let Some(arg) = node.find_arg(arg_side) {
    77 | |                         // if left side of = is arg and it has choices, offer them
    78 | |                         if !arg.choices.is_empty() {
    ...  |
    90 | |                 }
       | |_________________^
       |
       = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#collapsible_if
       = note: `-D clippy::collapsible-if` implied by `-D warnings`
       = help: to override `-D warnings` add `#[allow(clippy::collapsible_if)]`
    help: collapse nested if block
       |
    75 ~                 if let Some((arg_side, value_side)) = word.split_once("=")
    76 ~                     && let Some(arg) = node.find_arg(arg_side) {
    77 |                         // if left side of = is arg and it has choices, offer them
    ...
    88 |                         }
    89 ~                     }
       |

However, applying the suggested fix leads to compiler errors with the
stable toolchain:

     error[E0658]: `let` expressions in this position are unstable
      --> cli/bin/completions.rs:75:20
       |
    75 |                 if let Some((arg_side, value_side)) = word.split_once("=")
       |                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
       |
       = note: see issue #53667 <rust-lang/rust#53667> for more information

    error[E0658]: `let` expressions in this position are unstable
      --> cli/bin/completions.rs:76:24
       |
    76 |                     && let Some(arg) = node.find_arg(arg_side)
       |                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
       |
       = note: see issue #53667 <rust-lang/rust#53667> for more information

    For more information about this error, try `rustc --explain E0658`.
    error: could not compile `dataplane-cli` (bin "cli" test) due to 2 previous errors

This is apparently better supported in beta and nightly, but not in the
stable version just yet. Just silence the warning for now.

Same happens at a few other locations.

We should remove the macros and "collapse" the "if"s once we have
switched to Rust v1.88 as stable.

Signed-off-by: Quentin Monnet <[email protected]>

Author: qmonnet

cli/bin/completions.rs

@@ -72,6 +72,7 @@ impl Completer for CmdCompleter {
         // FIXME
         if let Some(word) = left.front() {
             if word.contains("=") {
+                #[allow(clippy::collapsible_if)]
                 if let Some((arg_side, value_side)) = word.split_once("=") {
                     if let Some(arg) = node.find_arg(arg_side) {
                         // if left side of = is arg and it has choices, offer them

interface-manager/src/interface/vtep.rs

@@ -86,6 +86,7 @@ impl Update for Manager<VtepProperties> {
     where
         Self: 'a,
     {
+        #[allow(clippy::collapsible_if)]
         if let InterfaceProperties::Vtep(props) = &observation.properties {
             if requirement == props {
                 return Ok(());

mgmt/src/frr/frrmi/mod.rs

@@ -234,6 +234,7 @@ impl FrrMi {
 
         if let Some(sock) = &mut self.sock {
             /* send the request: if sending fails, we may disconnect */
+            #[allow(clippy::collapsible_if)]
             if let Err(e) = send_msg(sock, genid, msg.as_bytes()).await {
                 if matches!(e, FrrErr::PeerLeft | FrrErr::RxFail(_) | FrrErr::TxFail(_)) {
                     warn!("Got error: {e}. Disconnecting frrmi...");

mgmt/src/grpc/converter.rs

@@ -209,6 +209,7 @@ pub fn convert_ospf_config_from_grpc(
     let mut ospf = Ospf::new(router_id);
 
     // Set VRF name if present
+    #[allow(clippy::collapsible_if)]
     if let Some(vrf_name) = &ospf_config.vrf {
         if !vrf_name.is_empty() {
             ospf.set_vrf_name(vrf_name.clone());

mgmt/src/processor/gwconfigdb.rs

@@ -47,6 +47,7 @@ impl GwConfigDatabase {
         self.configs.get_mut(&generation)
     }
     pub fn unmark_current(&mut self, value: bool) {
+        #[allow(clippy::collapsible_if)]
         if let Some(genid) = &self.current {
             if let Some(config) = self.configs.get_mut(genid) {
                 config.set_applied(value);
@@ -127,6 +128,7 @@ impl GwConfigDatabase {
                 let previous = last.unwrap_or(ExternalConfig::BLANK_GENID);
                 info!("Rolling back to config '{}'...", previous);
                 let mut config = self.get_mut(previous);
+                #[allow(clippy::collapsible_if)]
                 if let Some(config) = &mut config {
                     if let Err(e) = config.apply(frrmi).await {
                         error!("Fatal: could not roll-back to previous config: {e}");

mgmt/src/processor/proc.rs

@@ -228,6 +228,7 @@ async fn start_grpc_server_unix(
     );
 
     // Remove existing socket file if present
+    #[allow(clippy::collapsible_if)]
     if socket_path.exists() {
         if let Err(e) = std::fs::remove_file(socket_path) {
             error!("Failed to remove existing socket file: {}", e);
@@ -236,6 +237,7 @@ async fn start_grpc_server_unix(
     }
 
     // Create parent directory if it doesn't exist
+    #[allow(clippy::collapsible_if)]
     if let Some(parent) = socket_path.parent() {
         if !parent.exists() {
             if let Err(e) = std::fs::create_dir_all(parent) {
@@ -270,6 +272,7 @@ async fn start_grpc_server_unix(
         .await;
 
     // Clean up the socket file after server shutdown
+    #[allow(clippy::collapsible_if)]
     if socket_path.exists() {
         if let Err(e) = std::fs::remove_file(socket_path) {
             error!("Failed to remove socket file: {}", e);

routing/src/interface.rs

@@ -258,6 +258,7 @@ impl IfTable {
     //////////////////////////////////////////////////////////////////
     pub fn detach_vrf_interfaces(&mut self, vrf: &Arc<RwLock<Vrf>>) {
         for iface in self.0.values_mut() {
+            #[allow(clippy::collapsible_if)]
             if let Some(if_vrf) = &iface.vrf {
                 if Arc::ptr_eq(if_vrf, vrf) {
                     iface.detach();

routing/src/nexthop.rs

@@ -279,6 +279,7 @@ impl NhopStore {
     pub(crate) fn del_nhop(&mut self, key: &NhopKey) {
         let target = Nhop::new_from_key(key);
         let mut remove: bool = false;
+        #[allow(clippy::collapsible_if)]
         if let Some(existing) = self.0.get(&target) {
             if Arc::strong_count(existing) == 1 {
                 remove = true;

routing/src/rmac.rs

@@ -47,6 +47,7 @@ impl RmacStore {
     /// Delete an rmac entry. The mac address must match (sanity)
     pub fn del_rmac(&mut self, vni: Vni, address: IpAddr, mac: Mac) {
         let key = (address, vni);
+        #[allow(clippy::collapsible_if)]
         if let Entry::Occupied(o) = self.0.entry(key) {
             if o.get().mac == mac {
                 self.0.remove_entry(&key);
@@ -57,6 +58,7 @@ impl RmacStore {
     /// Identical to[`add_rmac`], but getting the entry as param
     pub fn del_rmac_entry(&mut self, entry: RmacEntry) {
         let key = (entry.address, entry.vni);
+        #[allow(clippy::collapsible_if)]
         if let Entry::Occupied(o) = self.0.entry(key) {
             if o.get().mac == entry.mac {
                 self.0.remove_entry(&key);

routing/src/routingdb.rs

@@ -47,6 +47,7 @@ impl VrfTable {
         };
 
         /* Forbid VRF addition if one exists with same vni */
+        #[allow(clippy::collapsible_if)]
         if let Some(vni) = vni_checked {
             if self.by_vni.contains_key(&vni) {
                 return Err(RouterError::VniInUse(vni.as_u32()));
@@ -78,6 +79,7 @@ impl VrfTable {
     pub fn remove_vrf(&mut self, vrfid: VrfId, iftable: &mut IfTable) -> Result<(), RouterError> {
         if let Some(vrf) = self.by_id.remove(&vrfid) {
             iftable.detach_vrf_interfaces(&vrf);
+            #[allow(clippy::collapsible_if)]
             if let Ok(vrf) = vrf.read() {
                 if let Some(vni) = vrf.vni {
                     self.by_vni.remove(&vni);

routing/src/rpc_adapt.rs

@@ -45,6 +45,7 @@ impl From<ForwardAction> for FwAction {
 impl From<&NextHop> for RouteNhop {
     fn from(nh: &NextHop) -> Self {
         let mut encap = nh.encap.as_ref().map(Encapsulation::from);
+        #[allow(clippy::collapsible_if)]
         if let Some(Encapsulation::Vxlan(vxlan)) = &mut encap {
             if let Some(address) = nh.address {
                 vxlan.remote = address;