Auto merge of #62253 - Centril:rollup-115uuuq, r=Centril

Rollup of 8 pull requests

Successful merges:

 - #62062 (Use a more efficient iteration order for forward dataflow)
 - #62063 (Use a more efficient iteration order for backward dataflow)
 - #62224 (rustdoc: remove unused derives and variants)
 - #62228 (Extend the #[must_use] lint to boxed types)
 - #62235 (Extend the `#[must_use]` lint to arrays)
 - #62239 (Fix a typo)
 - #62241 (Always parse 'async unsafe fn' + properly ban in 2015)
 - #62248 (before_exec actually will only get deprecated with 1.37)

Failed merges:

r? @ghost

src/test/ui/async-await/async-await.rs

@@ -134,11 +134,15 @@ trait Bar {
 }
 
 impl Foo {
-    async fn async_method(x: u8) -> u8 {
+    async fn async_assoc_item(x: u8) -> u8 {
         unsafe {
             unsafe_async_fn(x).await
         }
     }
+
+    async unsafe fn async_unsafe_assoc_item(x: u8) -> u8 {
+        unsafe_async_fn(x).await
+    }
 }
 
 fn test_future_yields_once_then_returns<F, Fut>(f: F)
@@ -180,12 +184,17 @@ fn main() {
         async_fn,
         generic_async_fn,
         async_fn_with_internal_borrow,
-        Foo::async_method,
+        Foo::async_assoc_item,
         |x| {
             async move {
                 unsafe { unsafe_async_fn(x).await }
             }
         },
+        |x| {
+            async move {
+                unsafe { Foo::async_unsafe_assoc_item(x).await }
+            }
+        },
     }
     test_with_borrow! {
         async_block_with_borrow_named_lifetime,

src/test/ui/async-await/edition-deny-async-fns-2015.rs

@@ -28,6 +28,12 @@ fn main() {
         async fn foo() {} //~ ERROR `async fn` is not permitted in the 2015 edition
     }
 
+    accept_item! {
+        impl Foo {
+            async fn bar() {} //~ ERROR `async fn` is not permitted in the 2015 edition
+        }
+    }
+
     let inside_closure = || {
         async fn bar() {} //~ ERROR `async fn` is not permitted in the 2015 edition
     };

src/test/ui/async-await/edition-deny-async-fns-2015.stderr

@@ -23,7 +23,19 @@ LL | async fn async_baz() {
    | ^^^^^
 
 error[E0670]: `async fn` is not permitted in the 2015 edition
-  --> $DIR/edition-deny-async-fns-2015.rs:32:9
+  --> $DIR/edition-deny-async-fns-2015.rs:16:5
+   |
+LL |     async fn foo() {}
+   |     ^^^^^
+
+error[E0670]: `async fn` is not permitted in the 2015 edition
+  --> $DIR/edition-deny-async-fns-2015.rs:20:5
+   |
+LL |     async fn foo() {}
+   |     ^^^^^
+
+error[E0670]: `async fn` is not permitted in the 2015 edition
+  --> $DIR/edition-deny-async-fns-2015.rs:38:9
    |
 LL |         async fn bar() {}
    |         ^^^^^
@@ -35,10 +47,10 @@ LL |         async fn foo() {}
    |         ^^^^^
 
 error[E0670]: `async fn` is not permitted in the 2015 edition
-  --> $DIR/edition-deny-async-fns-2015.rs:16:5
+  --> $DIR/edition-deny-async-fns-2015.rs:33:13
    |
-LL |     async fn foo() {}
-   |     ^^^^^
+LL |             async fn bar() {}
+   |             ^^^^^
 
 error[E0706]: trait fns cannot be declared `async`
   --> $DIR/edition-deny-async-fns-2015.rs:20:5
@@ -46,12 +58,6 @@ error[E0706]: trait fns cannot be declared `async`
 LL |     async fn foo() {}
    |     ^^^^^^^^^^^^^^^^^
 
-error[E0670]: `async fn` is not permitted in the 2015 edition
-  --> $DIR/edition-deny-async-fns-2015.rs:20:5
-   |
-LL |     async fn foo() {}
-   |     ^^^^^
-
-error: aborting due to 9 previous errors
+error: aborting due to 10 previous errors
 
 For more information about this error, try `rustc --explain E0670`.

src/test/ui/async-await/no-unsafe-async.rs

@@ -0,0 +1,11 @@
+// edition:2018
+
+struct S;
+
+impl S {
+    #[cfg(FALSE)]
+    unsafe async fn g() {} //~ ERROR expected one of `extern` or `fn`, found `async`
+}
+
+#[cfg(FALSE)]
+unsafe async fn f() {} //~ ERROR expected one of `extern`, `fn`, or `{`, found `async`

src/test/ui/async-await/no-unsafe-async.stderr

@@ -0,0 +1,14 @@
+error: expected one of `extern` or `fn`, found `async`
+  --> $DIR/no-unsafe-async.rs:7:12
+   |
+LL |     unsafe async fn g() {}
+   |            ^^^^^ expected one of `extern` or `fn` here
+
+error: expected one of `extern`, `fn`, or `{`, found `async`
+  --> $DIR/no-unsafe-async.rs:11:8
+   |
+LL | unsafe async fn f() {}
+   |        ^^^^^ expected one of `extern`, `fn`, or `{` here
+
+error: aborting due to 2 previous errors
+

src/test/ui/lint/must_use-array.rs

@@ -0,0 +1,47 @@
+#![deny(unused_must_use)]
+
+#[must_use]
+struct S;
+
+struct A;
+
+#[must_use]
+trait T {}
+
+impl T for A {}
+
+fn empty() -> [S; 0] {
+    []
+}
+
+fn singleton() -> [S; 1] {
+    [S]
+}
+
+fn many() -> [S; 4] {
+    [S, S, S, S]
+}
+
+fn array_of_impl_trait() -> [impl T; 2] {
+    [A, A]
+}
+
+fn impl_array() -> [(u8, Box<dyn T>); 2] {
+    [(0, Box::new(A)), (0, Box::new(A))]
+}
+
+fn array_of_arrays_of_arrays() -> [[[S; 1]; 2]; 1] {
+    [[[S], [S]]]
+}
+
+fn main() {
+    empty(); // ok
+    singleton(); //~ ERROR unused array of `S` that must be used
+    many(); //~ ERROR unused array of `S` that must be used
+    ([S], 0, ()); //~ ERROR unused array of `S` in tuple element 0 that must be used
+    array_of_impl_trait(); //~ ERROR unused array of implementers of `T` that must be used
+    impl_array();
+    //~^ ERROR unused array of boxed `T` trait objects in tuple element 1 that must be used
+    array_of_arrays_of_arrays();
+    //~^ ERROR unused array of arrays of arrays of `S` that must be used
+}

src/test/ui/lint/must_use-array.stderr

@@ -0,0 +1,44 @@
+error: unused array of `S` that must be used
+  --> $DIR/must_use-array.rs:39:5
+   |
+LL |     singleton();
+   |     ^^^^^^^^^^^^
+   |
+note: lint level defined here
+  --> $DIR/must_use-array.rs:1:9
+   |
+LL | #![deny(unused_must_use)]
+   |         ^^^^^^^^^^^^^^^
+
+error: unused array of `S` that must be used
+  --> $DIR/must_use-array.rs:40:5
+   |
+LL |     many();
+   |     ^^^^^^^
+
+error: unused array of `S` in tuple element 0 that must be used
+  --> $DIR/must_use-array.rs:41:6
+   |
+LL |     ([S], 0, ());
+   |      ^^^
+
+error: unused array of implementers of `T` that must be used
+  --> $DIR/must_use-array.rs:42:5
+   |
+LL |     array_of_impl_trait();
+   |     ^^^^^^^^^^^^^^^^^^^^^^
+
+error: unused array of boxed `T` trait objects in tuple element 1 that must be used
+  --> $DIR/must_use-array.rs:43:5
+   |
+LL |     impl_array();
+   |     ^^^^^^^^^^^^^
+
+error: unused array of arrays of arrays of `S` that must be used
+  --> $DIR/must_use-array.rs:45:5
+   |
+LL |     array_of_arrays_of_arrays();
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 6 previous errors
+

src/test/ui/lint/must_use-trait.rs

@@ -17,6 +17,23 @@ fn get_critical() -> impl NotSoCritical + Critical + DecidedlyUnimportant {
     Anon {}
 }
 
+fn get_boxed_critical() -> Box<dyn Critical> {
+    Box::new(Anon {})
+}
+
+fn get_nested_boxed_critical() -> Box<Box<dyn Critical>> {
+    Box::new(Box::new(Anon {}))
+}
+
+fn get_critical_tuple() -> (u32, Box<dyn Critical>, impl Critical, ()) {
+    (0, get_boxed_critical(), get_critical(), ())
+}
+
 fn main() {
     get_critical(); //~ ERROR unused implementer of `Critical` that must be used
+    get_boxed_critical(); //~ ERROR unused boxed `Critical` trait object that must be used
+    get_nested_boxed_critical();
+    //~^ ERROR unused boxed boxed `Critical` trait object that must be used
+    get_critical_tuple(); //~ ERROR unused boxed `Critical` trait object in tuple element 1
+    //~^ ERROR unused implementer of `Critical` in tuple element 2
 }

src/test/ui/lint/must_use-trait.stderr

@@ -1,5 +1,5 @@
 error: unused implementer of `Critical` that must be used
-  --> $DIR/must_use-trait.rs:21:5
+  --> $DIR/must_use-trait.rs:33:5
    |
 LL |     get_critical();
    |     ^^^^^^^^^^^^^^^
@@ -10,5 +10,29 @@ note: lint level defined here
 LL | #![deny(unused_must_use)]
    |         ^^^^^^^^^^^^^^^
 
-error: aborting due to previous error
+error: unused boxed `Critical` trait object that must be used
+  --> $DIR/must_use-trait.rs:34:5
+   |
+LL |     get_boxed_critical();
+   |     ^^^^^^^^^^^^^^^^^^^^^
+
+error: unused boxed boxed `Critical` trait object that must be used
+  --> $DIR/must_use-trait.rs:35:5
+   |
+LL |     get_nested_boxed_critical();
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: unused boxed `Critical` trait object in tuple element 1 that must be used
+  --> $DIR/must_use-trait.rs:37:5
+   |
+LL |     get_critical_tuple();
+   |     ^^^^^^^^^^^^^^^^^^^^^
+
+error: unused implementer of `Critical` in tuple element 2 that must be used
+  --> $DIR/must_use-trait.rs:37:5
+   |
+LL |     get_critical_tuple();
+   |     ^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 5 previous errors