Allow lint in miri tests.

Author: cjgillot

src/tools/miri/tests/pass/async-fn.rs

@@ -1,4 +1,5 @@
 #![feature(never_type)]
+#![allow(unreachable_code)]
 
 use std::future::Future;
 
@@ -41,7 +42,6 @@ async fn includes_never(crash: bool, x: u32) -> u32 {
 }
 
 async fn partial_init(x: u32) -> u32 {
-    #[allow(unreachable_code)]
     let _x: (String, !) = (String::new(), return async { x + x }.await);
 }
 

src/tools/miri/tests/pass/generator.rs

@@ -1,6 +1,7 @@
 //@revisions: stack tree
 //@[tree]compile-flags: -Zmiri-tree-borrows
 #![feature(generators, generator_trait, never_type)]
+#![allow(unreachable_code)]
 
 use std::fmt::Debug;
 use std::mem::ManuallyDrop;
@@ -104,14 +105,12 @@ fn basic() {
         }
         #[allow(unused)]
         let x = never();
-        #[allow(unreachable_code)]
         yield 2;
         drop(x);
     });
 
     finish(3, || {
         yield 1;
-        #[allow(unreachable_code)]
         let _x: (String, !) = (String::new(), {
             yield 2;
             return;
@@ -176,7 +175,6 @@ fn smoke_resume_arg() {
         )
     });
 
-    #[allow(unreachable_code)]
     expect_drops(2, || drain(&mut |a| yield return a, vec![(DropMe, Complete(DropMe))]));
 
     expect_drops(2, || {