Auto merge of rust-lang#87569 - JohnTitor:rollup-7ydfetw, r=JohnTitor

Rollup of 10 pull requests

Successful merges:

 - rust-lang#81050 (Stabilize core::task::ready!)
 - rust-lang#81363 (Remove P: Unpin bound on impl Future for Pin)
 - rust-lang#86839 (Add doc aliases to fs.rs)
 - rust-lang#87435 (fix example code for E0617)
 - rust-lang#87451 (Add support for tuple struct field documentation)
 - rust-lang#87491 (Integrate context into the memorial to Anna)
 - rust-lang#87521 (Add long explanation for E0498)
 - rust-lang#87527 (Don't run MIR unsafeck at all when using `-Zthir-unsafeck`)
 - rust-lang#87550 (Add `CI_ONLY_WHEN_CHANNEL` and run `x86_64-gnu-stable` only on nightly)
 - rust-lang#87565 (Use backticks when referring to `core::future::Ready` in panic message)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

Author: bors

.github/workflows/ci.yml

@@ -263,6 +263,7 @@ jobs:
             env:
               IMAGE: x86_64-gnu
               RUST_CI_OVERRIDE_RELEASE_CHANNEL: stable
+              CI_ONLY_WHEN_CHANNEL: nightly
             os: ubuntu-latest-xl
           - name: x86_64-gnu-aux
             os: ubuntu-latest-xl

compiler/rustc_error_codes/src/error_codes.rs

@@ -248,6 +248,7 @@ E0493: include_str!("./error_codes/E0493.md"),
 E0495: include_str!("./error_codes/E0495.md"),
 E0496: include_str!("./error_codes/E0496.md"),
 E0497: include_str!("./error_codes/E0497.md"),
+E0498: include_str!("./error_codes/E0498.md"),
 E0499: include_str!("./error_codes/E0499.md"),
 E0500: include_str!("./error_codes/E0500.md"),
 E0501: include_str!("./error_codes/E0501.md"),
@@ -604,7 +605,6 @@ E0783: include_str!("./error_codes/E0783.md"),
 //  E0488, // lifetime of variable does not enclose its declaration
 //  E0489, // type/lifetime parameter not in scope here
     E0490, // a value of type `..` is borrowed for too long
-    E0498,  // malformed plugin attribute
     E0514, // metadata version mismatch
     E0519, // local crate and dependency have same (crate-name, disambiguator)
     // two dependencies have same (crate-name, disambiguator) but different SVH

compiler/rustc_error_codes/src/error_codes/E0498.md

@@ -0,0 +1,22 @@
+The `plugin` attribute was malformed.
+
+Erroneous code example:
+
+```compile_fail,E0498
+#![feature(plugin)]
+#![plugin(foo(args))] // error: invalid argument
+#![plugin(bar="test")] // error: invalid argument
+```
+
+The `#[plugin]` attribute should take a single argument: the name of the plugin.
+
+For example, for the plugin `foo`:
+
+```ignore (requires external plugin crate)
+#![feature(plugin)]
+#![plugin(foo)] // ok!
+```
+
+See the [`plugin` feature] section of the Unstable book for more details.
+
+[`plugin` feature]: https://doc.rust-lang.org/nightly/unstable-book/language-features/plugin.html

compiler/rustc_error_codes/src/error_codes/E0617.md

@@ -3,12 +3,13 @@ Attempted to pass an invalid type of variable into a variadic function.
 Erroneous code example:
 
 ```compile_fail,E0617
+# use std::os::raw::{c_char, c_int};
 extern "C" {
-    fn printf(c: *const i8, ...);
+    fn printf(format: *const c_char, ...) -> c_int;
 }
 
 unsafe {
-    printf(::std::ptr::null(), 0f32);
+    printf("%f\n\0".as_ptr() as _, 0f32);
     // error: cannot pass an `f32` to variadic function, cast to `c_double`
 }
 ```
@@ -21,10 +22,12 @@ to import from `std::os::raw`).
 In this case, `c_double` has the same size as `f64` so we can use it directly:
 
 ```no_run
+# use std::os::raw::{c_char, c_int};
 # extern "C" {
-#     fn printf(c: *const i8, ...);
+#     fn printf(format: *const c_char, ...) -> c_int;
 # }
+
 unsafe {
-    printf(::std::ptr::null(), 0f64); // ok!
+    printf("%f\n\0".as_ptr() as _, 0f64); // ok!
 }
 ```

compiler/rustc_mir/src/transform/mod.rs

@@ -259,10 +259,12 @@ fn mir_const<'tcx>(
     }
 
     // Unsafety check uses the raw mir, so make sure it is run.
-    if let Some(param_did) = def.const_param_did {
-        tcx.ensure().unsafety_check_result_for_const_arg((def.did, param_did));
-    } else {
-        tcx.ensure().unsafety_check_result(def.did);
+    if !tcx.sess.opts.debugging_opts.thir_unsafeck {
+        if let Some(param_did) = def.const_param_did {
+            tcx.ensure().unsafety_check_result_for_const_arg((def.did, param_did));
+        } else {
+            tcx.ensure().unsafety_check_result(def.did);
+        }
     }
 
     let mut body = tcx.mir_built(def).steal();

library/core/src/future/future.rs

@@ -111,11 +111,11 @@ impl<F: ?Sized + Future + Unpin> Future for &mut F {
 #[stable(feature = "futures_api", since = "1.36.0")]
 impl<P> Future for Pin<P>
 where
-    P: Unpin + ops::DerefMut<Target: Future>,
+    P: ops::DerefMut<Target: Future>,
 {
     type Output = <<P as ops::Deref>::Target as Future>::Output;
 
     fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
-        Pin::get_mut(self).as_mut().poll(cx)
+        <P::Target as Future>::poll(self.as_deref_mut(), cx)
     }
 }

library/core/src/future/ready.rs

@@ -20,7 +20,7 @@ impl<T> Future for Ready<T> {
 
     #[inline]
     fn poll(mut self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<T> {
-        Poll::Ready(self.0.take().expect("Ready polled after completion"))
+        Poll::Ready(self.0.take().expect("`Ready` polled after completion"))
     }
 }
 

library/core/src/lib.rs

@@ -128,6 +128,7 @@
 #![feature(exhaustive_patterns)]
 #![feature(no_core)]
 #![feature(auto_traits)]
+#![feature(pin_deref_mut)]
 #![feature(prelude_import)]
 #![feature(ptr_metadata)]
 #![feature(repr_simd, platform_intrinsics)]

library/core/src/pin.rs

@@ -802,6 +802,44 @@ impl<T: ?Sized> Pin<&'static T> {
     }
 }
 
+impl<'a, P: DerefMut> Pin<&'a mut Pin<P>> {
+    /// Gets a pinned mutable reference from this nested pinned pointer.
+    ///
+    /// This is a generic method to go from `Pin<&mut Pin<Pointer<T>>>` to `Pin<&mut T>`. It is
+    /// safe because the existence of a `Pin<Pointer<T>>` ensures that the pointee, `T`, cannot
+    /// move in the future, and this method does not enable the pointee to move. "Malicious"
+    /// implementations of `P::DerefMut` are likewise ruled out by the contract of
+    /// `Pin::new_unchecked`.
+    #[unstable(feature = "pin_deref_mut", issue = "86918")]
+    #[inline(always)]
+    pub fn as_deref_mut(self) -> Pin<&'a mut P::Target> {
+        // SAFETY: What we're asserting here is that going from
+        //
+        //     Pin<&mut Pin<P>>
+        //
+        // to
+        //
+        //     Pin<&mut P::Target>
+        //
+        // is safe.
+        //
+        // We need to ensure that two things hold for that to be the case:
+        //
+        // 1) Once we give out a `Pin<&mut P::Target>`, an `&mut P::Target` will not be given out.
+        // 2) By giving out a `Pin<&mut P::Target>`, we do not risk of violating `Pin<&mut Pin<P>>`
+        //
+        // The existence of `Pin<P>` is sufficient to guarantee #1: since we already have a
+        // `Pin<P>`, it must already uphold the pinning guarantees, which must mean that
+        // `Pin<&mut P::Target>` does as well, since `Pin::as_mut` is safe. We do not have to rely
+        // on the fact that P is _also_ pinned.
+        //
+        // For #2, we need to ensure that code given a `Pin<&mut P::Target>` cannot cause the
+        // `Pin<P>` to move? That is not possible, since `Pin<&mut P::Target>` no longer retains
+        // any access to the `P` itself, much less the `Pin<P>`.
+        unsafe { self.get_unchecked_mut() }.as_mut()
+    }
+}
+
 impl<T: ?Sized> Pin<&'static mut T> {
     /// Get a pinned mutable reference from a static mutable reference.
     ///

library/core/src/task/mod.rs

@@ -11,5 +11,5 @@ mod wake;
 pub use self::wake::{Context, RawWaker, RawWakerVTable, Waker};
 
 mod ready;
-#[unstable(feature = "ready_macro", issue = "70922")]
+#[stable(feature = "ready_macro", since = "1.56.0")]
 pub use ready::ready;