chore: fix cargo clippy

Author: taisho6339

opentelemetry/src/context.rs

@@ -484,8 +484,11 @@ impl Drop for ContextGuard {
         if id > ContextStack::BASE_POS && id < ContextStack::MAX_POS {
             // Extract only the span to drop outside of borrow_mut to avoid panic
             // when the span's drop implementation calls Context::current()
+            #[cfg(feature = "trace")]
             let _to_drop =
                 CURRENT_CONTEXT.with(|context_stack| context_stack.borrow_mut().pop_id(id));
+            #[cfg(not(feature = "trace"))]
+            CURRENT_CONTEXT.with(|context_stack| context_stack.borrow_mut().pop_id(id));
             // Span (if any) is automatically dropped here, outside of borrow_mut scope
         }
     }
@@ -587,8 +590,6 @@ impl ContextStack {
             );
             #[cfg(feature = "trace")]
             return None;
-            #[cfg(not(feature = "trace"))]
-            return;
         }
         let len: u16 = self.stack.len() as u16;
         // Are we at the top of the [`ContextStack`]?
@@ -601,18 +602,19 @@ impl ContextStack {
             // empty context is always at the bottom of the stack if the
             // [`ContextStack`] is not empty.
             if let Some(Some(next_cx)) = self.stack.pop() {
-                let old_cx = std::mem::replace(&mut self.current_cx, next_cx);
                 // Extract and return only the span to avoid cloning the entire Context
                 #[cfg(feature = "trace")]
-                return old_cx.span;
-                #[cfg(not(feature = "trace"))]
-                return;
-            } else {
-                #[cfg(feature = "trace")]
-                return None;
+                {
+                    let old_cx = std::mem::replace(&mut self.current_cx, next_cx);
+                    return old_cx.span;
+                }
                 #[cfg(not(feature = "trace"))]
-                return;
+                {
+                    self.current_cx = next_cx;
+                }
             }
+            #[cfg(feature = "trace")]
+            return None;
         } else {
             // This is an out of order pop.
             if pos >= len {
@@ -625,16 +627,13 @@ impl ContextStack {
                 );
                 #[cfg(feature = "trace")]
                 return None;
-                #[cfg(not(feature = "trace"))]
-                return;
             }
             // Clear out the entry at the given id and extract its span
             #[cfg(feature = "trace")]
             return self.stack[pos as usize].take().and_then(|cx| cx.span);
             #[cfg(not(feature = "trace"))]
             {
                 self.stack[pos as usize] = None;
-                return;
             }
         }
     }