refactor: apply some clippy suggestions

tracing-attributes/src/expand.rs

@@ -4,9 +4,9 @@ use proc_macro2::TokenStream;
 use quote::{quote, quote_spanned, ToTokens};
 use syn::visit_mut::VisitMut;
 use syn::{
-    punctuated::Punctuated, spanned::Spanned, Block, Expr, ExprAsync, ExprCall, FieldPat, FnArg,
-    Ident, Item, ItemFn, Pat, PatIdent, PatReference, PatStruct, PatTuple, PatTupleStruct, PatType,
-    Path, ReturnType, Signature, Stmt, Token, Type, TypePath,
+    punctuated::Punctuated, spanned::Spanned, Expr, ExprAsync, ExprCall, FieldPat, FnArg, Ident,
+    Item, ItemFn, Pat, PatIdent, PatReference, PatStruct, PatTuple, PatTupleStruct, PatType, Path,
+    ReturnType, Signature, Stmt, Token, Type, TypePath,
 };
 
 use crate::{
@@ -794,20 +794,6 @@ impl<'a> VisitMut for IdentAndTypesRenamer<'a> {
     }
 }
 
-// A visitor struct that replace an async block by its patched version
-struct AsyncTraitBlockReplacer<'a> {
-    block: &'a Block,
-    patched_block: Block,
-}
-
-impl<'a> VisitMut for AsyncTraitBlockReplacer<'a> {
-    fn visit_block_mut(&mut self, i: &mut Block) {
-        if i == self.block {
-            *i = self.patched_block.clone();
-        }
-    }
-}
-
 // Replaces any `impl Trait` with `_` so it can be used as the type in
 // a `let` statement's LHS.
 struct ImplTraitEraser;

tracing-attributes/tests/instrument.rs

@@ -100,7 +100,7 @@ fn fields() {
 
 #[test]
 fn skip() {
-    struct UnDebug(pub u32);
+    struct UnDebug;
 
     #[instrument(target = "my_target", level = "debug", skip(_arg2, _arg3))]
     fn my_fn(arg1: usize, _arg2: UnDebug, _arg3: UnDebug) {}
@@ -134,8 +134,8 @@ fn skip() {
         .run_with_handle();
 
     with_default(collector, || {
-        my_fn(2, UnDebug(0), UnDebug(1));
-        my_fn(3, UnDebug(0), UnDebug(1));
+        my_fn(2, UnDebug, UnDebug);
+        my_fn(3, UnDebug, UnDebug);
     });
 
     handle.assert_finished();

tracing-core/src/callsite.rs

@@ -169,7 +169,6 @@ mod inner {
     use super::*;
     use once_cell::sync::Lazy;
     use std::sync::RwLock;
-    use std::vec::Vec;
 
     type Dispatchers = Vec<dispatch::Registrar>;
 

tracing-core/src/dispatch.rs

@@ -510,6 +510,7 @@ pub(crate) fn get_global() -> &'static Dispatch {
     unsafe {
         // This is safe given the invariant that setting the global dispatcher
         // also sets `GLOBAL_INIT` to `INITIALIZED`.
+        #[allow(static_mut_refs)]
         &GLOBAL_DISPATCH
     }
 }

tracing-core/src/field.rs

@@ -966,8 +966,8 @@ mod test {
     use crate::metadata::{Kind, Level, Metadata};
 
     // Make sure TEST_CALLSITE_* have non-zero size, so they can't be located at the same address.
-    struct TestCallsite1(u8);
-    static TEST_CALLSITE_1: TestCallsite1 = TestCallsite1(0);
+    struct TestCallsite1;
+    static TEST_CALLSITE_1: TestCallsite1 = TestCallsite1;
     static TEST_META_1: Metadata<'static> = metadata! {
         name: "field_test1",
         target: module_path!(),
@@ -987,8 +987,8 @@ mod test {
         }
     }
 
-    struct TestCallsite2(u8);
-    static TEST_CALLSITE_2: TestCallsite2 = TestCallsite2(0);
+    struct TestCallsite2;
+    static TEST_CALLSITE_2: TestCallsite2 = TestCallsite2;
     static TEST_META_2: Metadata<'static> = metadata! {
         name: "field_test2",
         target: module_path!(),

tracing-futures/src/executor/futures_01.rs

@@ -35,7 +35,7 @@ where
 }
 
 #[cfg(feature = "tokio")]
-#[allow(unreachable_pub)] // https://github.com/rust-lang/rust/issues/57411
+#[allow(unreachable_pub,unused_imports)] // https://github.com/rust-lang/rust/issues/57411
 pub use self::tokio::*;
 
 #[cfg(feature = "tokio")]

tracing-futures/src/executor/mod.rs

@@ -9,4 +9,5 @@ pub use self::futures_preview::*;
 #[cfg(feature = "futures-03")]
 mod futures_03;
 #[cfg(feature = "futures-03")]
+#[allow(unreachable_pub,unused_imports)]
 pub use self::futures_03::*;

tracing-futures/tests/std_future.rs

@@ -55,6 +55,7 @@ fn span_on_drop() {
         }
     }
 
+    #[allow(dead_code)] // We use it to test drop behavior.
     struct Fut(Option<AssertSpanOnDrop>);
 
     impl Future for Fut {

tracing-subscriber/src/fmt/time/chrono_crate.rs

@@ -108,20 +108,15 @@ impl FormatTime for ChronoUtc {
 /// the supported syntax.
 ///
 /// [`chrono::format::strftime`]: https://docs.rs/chrono/0.4.9/chrono/format/strftime/index.html
-#[derive(Debug, Clone, Eq, PartialEq)]
+#[derive(Debug, Clone, Eq, PartialEq, Default)]
 enum ChronoFmtType {
+    #[default]
     /// Format according to the RFC 3339 convention.
     Rfc3339,
     /// Format according to a custom format string.
     Custom(String),
 }
 
-impl Default for ChronoFmtType {
-    fn default() -> Self {
-        ChronoFmtType::Rfc3339
-    }
-}
-
 #[cfg(test)]
 mod tests {
     use crate::fmt::format::Writer;

tracing-subscriber/src/registry/sharded.rs

@@ -592,6 +592,7 @@ mod tests {
         closed: Vec<(&'static str, Weak<()>)>,
     }
 
+    #[allow(dead_code)] // Used in test.
     struct SetRemoved(Arc<()>);
 
     impl<C> Subscribe<C> for CloseSubscriber

tracing/src/instrument.rs

@@ -1,7 +1,6 @@
 use crate::span::Span;
 use core::{
     future::Future,
-    marker::Sized,
     mem::ManuallyDrop,
     pin::Pin,
     task::{Context, Poll},

tracing/tests/instrument.rs

@@ -21,6 +21,7 @@ fn span_on_drop() {
         }
     }
 
+    #[allow(dead_code)] // We use it to test drop behavior.
     struct Fut(Option<AssertSpanOnDrop>);
 
     impl Future for Fut {