Resolve dead_code and unused_variables warnings

Summary:
Rust 1.79's dead code scanner is more precise than previous versions. `pub` is no longer sufficient to hide a data structure field from the lint. It actually looks at whether an unused pub field is reachable from outside the crate.

In the following example, the field `field` is considered dead code by Rust 1.79 and not by 1.78.

```lang=rust
mod module {
    pub struct Struct {
        pub field: i32,
    }

    impl Struct {
        pub fn new() -> Self {
            Struct { field: 0 }
        }
    }
}

pub fn repro() {
    let _ = Struct::new();
}
```

Reviewed By: zertosh, JakobDegen

Differential Revision: D59623034

fbshipit-source-id: 6a4e2fb6e5be410d5127b451704df74ecdd42bf0

detcore/src/scheduler.rs

@@ -84,12 +84,15 @@ pub type Seconds = u32;
 #[derive(Debug, Clone)]
 pub struct Action {
     /// Id for the action
+    #[allow(dead_code)]
     pub action_id: ActionID,
 
     /// The action's side effects are completed.
+    #[allow(dead_code)]
     pub completion: Ivar<()>,
 
     /// Which action gets the lock after me.
+    #[allow(dead_code)]
     pub successors: HashMap<ResourceID, ActionID>,
 }
 
@@ -232,6 +235,7 @@ pub struct Scheduler {
     pub next_turns: BTreeMap<DetTid, ThreadNextTurn>,
 
     /// The current set of actions in the background.
+    #[allow(dead_code)]
     pub bg_action_pool: HashMap<ActionID, Action>,
 
     /// The logical, global time consumed by actions that have been committed already.
@@ -242,6 +246,7 @@ pub struct Scheduler {
 
     /// Ac table of "locks held": which action is using which resources.
     /// A given resource can be held by at most one action at a given time.
+    #[allow(dead_code)]
     pub resources: HashMap<ResourceID, ActionID>,
 
     /// Initially false, set to true when the first thread is running.
@@ -726,6 +731,7 @@ pub struct ConsumeResult {
     /// Should we print the stacktrace in the guest, as per --stacktrace-event
     pub print_stack: MaybePrintStack,
     /// The number of this event in the global total order of events.
+    #[allow(dead_code)]
     pub event_ix: u64,
 }
 

hermit-verify/src/common/env.rs

@@ -199,6 +199,7 @@ impl EnvPath {
 #[derive(Clone)]
 pub struct RunEnvironment {
     // Root directory for one run
+    #[allow(dead_code)]
     pub temp_dir: PathBuf,
 
     // Path to log file