[master] Upgrade Rust toolchain (Azure#6126)

Unifies toolchain files.

## Azure IoT Edge PR checklist:

mqtt/mqtt-bridge/src/messages.rs

@@ -161,9 +161,7 @@ where
                     return match self.store.push(&publication) {
                         Ok(_) => Ok(Handled::Fully),
                         Err(
-                            err
-                            @
-                            PersistError::RingBuffer(RingBufferError::InsufficientSpace {
+                            err @ PersistError::RingBuffer(RingBufferError::InsufficientSpace {
                                 ..
                             }),
                         ) => {

mqtt/mqtt-bridge/src/persist/waking_state/ring_buffer/mod.rs

@@ -981,12 +981,11 @@ mod tests {
 
             for (key, _) in batch.drain(..) {
                 let removed = rb.pop().expect("unable to pop publication");
-                if removed != key {
-                    panic!(
-                        "invalid publication removed {} but expected {}",
-                        removed, key
-                    );
-                }
+                assert_eq!(
+                    removed, key,
+                    "invalid publication removed {} but expected {}",
+                    removed, key
+                );
             }
 
             read = rb.metadata.file_pointers.read_begin;

mqtt/mqtt-broker/src/state_change.rs

@@ -62,7 +62,7 @@ impl<'a> TryFrom<StateChange<'a>> for proto::Publication {
                 let payload = subscriptions
                     .map(|subscriptions| serde_json::to_string(&subscriptions))
                     .transpose()?
-                    .map(|json| json.into())
+                    .map(Into::into)
                     .unwrap_or_default();
 
                 proto::Publication {

mqtt/mqtt-edgehub/src/auth/authentication/edgehub.rs

@@ -109,10 +109,10 @@ impl<'a> EdgeHubAuthRequest<'a> {
             version: API_VERSION,
             username: context.username(),
             password: context.password(),
-            certificate: context.certificate().map(|cert| cert.as_ref()),
+            certificate: context.certificate().map(AsRef::as_ref),
             certificate_chain: context
                 .cert_chain()
-                .map(|chain| chain.iter().map(|cert| cert.as_ref()).collect()),
+                .map(|chain| chain.iter().map(AsRef::as_ref).collect()),
         }
     }
 }

mqtt/mqtt3/src/client/mod.rs

@@ -328,9 +328,7 @@ where
                                     client_id,
                                     crate::proto::ClientId::ServerGenerated,
                                 ) {
-                                    id
-                                    @
-                                    (crate::proto::ClientId::ServerGenerated
+                                    id @ (crate::proto::ClientId::ServerGenerated
                                     | crate::proto::ClientId::IdWithCleanSession(_)) => id,
                                     crate::proto::ClientId::IdWithExistingSession(id) => {
                                         crate::proto::ClientId::IdWithCleanSession(id)

mqtt/mqtt3/src/proto/mod.rs

@@ -152,21 +152,12 @@ where
 /// These numbers are encoded with a variable-length scheme that uses the MSB of each byte as a continuation bit.
 ///
 /// Ref: 2.2.3 Remaining Length
-#[derive(Debug)]
+#[derive(Debug, Default)]
 pub struct RemainingLengthDecoder {
     result: usize,
     num_bytes_read: usize,
 }
 
-impl Default for RemainingLengthDecoder {
-    fn default() -> Self {
-        RemainingLengthDecoder {
-            result: 0,
-            num_bytes_read: 0,
-        }
-    }
-}
-
 impl tokio_util::codec::Decoder for RemainingLengthDecoder {
     type Item = usize;
     type Error = DecodeError;

mqtt/policy/src/validator.rs

@@ -25,7 +25,7 @@ impl PolicyValidator for DefaultValidator {
         let errors = definition
             .statements()
             .iter()
-            .flat_map(|statement| visit_statement(statement))
+            .flat_map(visit_statement)
             .collect::<Vec<_>>();
 
         if !errors.is_empty() {

rust-toolchain.toml

@@ -0,0 +1,2 @@
+[toolchain]
+channel = "1.58"

scripts/linux/generic-rust/install.sh

@@ -49,7 +49,7 @@ function install_rust()
     # but it's simpler to just always `update` whatever toolchain it is. `update` installs the toolchain
     # if it hasn't already been installed, so this also works for pinned versions.
     source $HOME/.cargo/env
-    rustup update "$(< "$PROJECT_ROOT/rust-toolchain")"
+    rustup update "$(rustup show active-toolchain | sed 's/ .*//')"
 }
 
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