Fixes in various places

compiler/rustc_codegen_cranelift/example/mini_core_hello_world.rs

@@ -578,6 +578,7 @@ pub enum E2<X> {
     V4,
 }
 
+#[allow(unreachable_patterns)]
 fn check_niche_behavior() {
     if let E1::V2 { .. } = (E1::V1 { f: true }) {
         intrinsics::abort();

compiler/rustc_codegen_gcc/example/mini_core_hello_world.rs

@@ -432,6 +432,7 @@ pub enum E2<X> {
     V4,
 }
 
+#[allow(unreachable_patterns)]
 fn check_niche_behavior () {
     if let E1::V2 { .. } = (E1::V1 { f: true }) {
         intrinsics::abort();

src/tools/clippy/tests/ui/single_match_else.fixed

@@ -90,7 +90,7 @@ fn main() {
 
     // lint here
     use std::convert::Infallible;
-    if let Ok(a) = Result::<i32, Infallible>::Ok(1) { println!("${:?}", a) } else {
+    if let Ok(a) = Result::<i32, &Infallible>::Ok(1) { println!("${:?}", a) } else {
         println!("else block");
         return;
     }

src/tools/clippy/tests/ui/single_match_else.rs

@@ -99,7 +99,7 @@ fn main() {
 
     // lint here
     use std::convert::Infallible;
-    match Result::<i32, Infallible>::Ok(1) {
+    match Result::<i32, &Infallible>::Ok(1) {
         Ok(a) => println!("${:?}", a),
         Err(_) => {
             println!("else block");

src/tools/clippy/tests/ui/single_match_else.stderr

@@ -64,7 +64,7 @@ LL +     }
 error: you seem to be trying to use `match` for destructuring a single pattern. Consider using `if let`
   --> tests/ui/single_match_else.rs:102:5
    |
-LL | /     match Result::<i32, Infallible>::Ok(1) {
+LL | /     match Result::<i32, &Infallible>::Ok(1) {
 LL | |         Ok(a) => println!("${:?}", a),
 LL | |         Err(_) => {
 LL | |             println!("else block");
@@ -75,7 +75,7 @@ LL | |     }
    |
 help: try
    |
-LL ~     if let Ok(a) = Result::<i32, Infallible>::Ok(1) { println!("${:?}", a) } else {
+LL ~     if let Ok(a) = Result::<i32, &Infallible>::Ok(1) { println!("${:?}", a) } else {
 LL +         println!("else block");
 LL +         return;
 LL +     }

src/tools/miri/src/eval.rs

@@ -441,6 +441,7 @@ pub fn eval_entry<'tcx>(
     let res = match res {
         Err(res) => res,
         // `Ok` can never happen
+        #[cfg(bootstrap)]
         Ok(never) => match never {},
     };
 

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

@@ -43,6 +43,7 @@ fn discriminant_overflow() {
     }
 }
 
+#[allow(unreachable_patterns)]
 fn more_discriminant_overflow() {
     pub enum Infallible {}