fix: new clippy/rust lints

Author: dpc

tracing-attributes/tests/instrument.rs

@@ -100,6 +100,7 @@ fn fields() {
 
 #[test]
 fn skip() {
+    #[allow(dead_code)]
     struct UnDebug(pub u32);
 
     #[instrument(target = "my_target", level = "debug", skip(_arg2, _arg3))]

tracing-core/src/dispatcher.rs

@@ -455,6 +455,7 @@ 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

@@ -1090,6 +1090,7 @@ mod test {
     use crate::stdlib::{borrow::ToOwned, string::String};
 
     // Make sure TEST_CALLSITE_* have non-zero size, so they can't be located at the same address.
+    #[allow(dead_code)]
     struct TestCallsite1(u8);
     static TEST_CALLSITE_1: TestCallsite1 = TestCallsite1(0);
     static TEST_META_1: Metadata<'static> = metadata! {
@@ -1111,6 +1112,7 @@ mod test {
         }
     }
 
+    #[allow(dead_code)]
     struct TestCallsite2(u8);
     static TEST_CALLSITE_2: TestCallsite2 = TestCallsite2(0);
     static TEST_META_2: Metadata<'static> = metadata! {

tracing/tests/instrument.rs

@@ -21,6 +21,7 @@ fn span_on_drop() {
         }
     }
 
+    #[allow(dead_code)]
     struct Fut(Option<AssertSpanOnDrop>);
 
     impl Future for Fut {