Auto merge of #118257 - mu001999:dead_code/trait, r=cjgillot

Make traits / trait methods detected by the dead code lint

Fixes #118139 and #41883

tests/fail/dyn-call-trait-mismatch.rs

@@ -1,4 +1,5 @@
 trait T1 {
+    #[allow(dead_code)]
     fn method1(self: Box<Self>);
 }
 trait T2 {

tests/fail/dyn-upcast-trait-mismatch.rs

@@ -2,30 +2,36 @@
 #![allow(incomplete_features)]
 
 trait Foo: PartialEq<i32> + std::fmt::Debug + Send + Sync {
+    #[allow(dead_code)]
     fn a(&self) -> i32 {
         10
     }
 
+    #[allow(dead_code)]
     fn z(&self) -> i32 {
         11
     }
 
+    #[allow(dead_code)]
     fn y(&self) -> i32 {
         12
     }
 }
 
 trait Bar: Foo {
+    #[allow(dead_code)]
     fn b(&self) -> i32 {
         20
     }
 
+    #[allow(dead_code)]
     fn w(&self) -> i32 {
         21
     }
 }
 
 trait Baz: Bar {
+    #[allow(dead_code)]
     fn c(&self) -> i32 {
         30
     }

tests/pass/cast-rfc0401-vtable-kinds.rs

@@ -9,6 +9,7 @@ trait Foo<T> {
     }
 }
 
+#[allow(dead_code)]
 trait Bar {
     fn bar(&self) {
         println!("Bar!");

tests/pass/dyn-upcast.rs

@@ -383,14 +383,17 @@ fn struct_() {
 
 fn replace_vptr() {
     trait A {
+        #[allow(dead_code)]
         fn foo_a(&self);
     }
 
     trait B {
+        #[allow(dead_code)]
         fn foo_b(&self);
     }
 
     trait C: A + B {
+        #[allow(dead_code)]
         fn foo_c(&self);
     }
 

tests/pass/weak_memory/weak.rs

@@ -11,6 +11,7 @@ use std::sync::atomic::Ordering::*;
 use std::sync::atomic::{fence, AtomicUsize};
 use std::thread::spawn;
 
+#[allow(dead_code)]
 #[derive(Copy, Clone)]
 struct EvilSend<T>(pub T);