Merge from rustc

20 files changed, 113 insertions, 160 deletions

diff --git a/library/core/src/array/mod.rs b/library/core/src/array/mod.rs
index 4476e3f7923..221ca91e005 100644
--- a/library/core/src/array/mod.rs
+++ b/library/core/src/array/mod.rs
@@ -588,7 +588,7 @@ impl<T, const N: usize> [T; N] {
     /// Returns a mutable slice containing the entire array. Equivalent to
     /// `&mut s[..]`.
     #[stable(feature = "array_as_slice", since = "1.57.0")]
-    #[rustc_const_unstable(feature = "const_array_as_mut_slice", issue = "133333")]
+    #[rustc_const_stable(feature = "const_array_as_mut_slice", since = "CURRENT_RUSTC_VERSION")]
     pub const fn as_mut_slice(&mut self) -> &mut [T] {
         self
     }
diff --git a/library/core/src/convert/mod.rs b/library/core/src/convert/mod.rs
index c542a28beb8..d86dc24fb57 100644
--- a/library/core/src/convert/mod.rs
+++ b/library/core/src/convert/mod.rs
@@ -575,7 +575,7 @@ pub trait Into<T>: Sized {
 #[rustc_diagnostic_item = "From"]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[rustc_on_unimplemented(on(
-    all(_Self = "&str", T = "alloc::string::String"),
+    all(Self = "&str", T = "alloc::string::String"),
     note = "to coerce a `{T}` into a `{Self}`, use `&*` as a prefix",
 ))]
 #[doc(search_unbox)]
diff --git a/library/core/src/ffi/c_str.rs b/library/core/src/ffi/c_str.rs
index ac07c645c01..825402116e5 100644
--- a/library/core/src/ffi/c_str.rs
+++ b/library/core/src/ffi/c_str.rs
@@ -511,13 +511,8 @@ impl CStr {
     /// # Examples
     ///
     /// ```
-    /// use std::ffi::CStr;
-    ///
-    /// let cstr = CStr::from_bytes_with_nul(b"foo\0").unwrap();
-    /// assert_eq!(cstr.count_bytes(), 3);
-    ///
-    /// let cstr = CStr::from_bytes_with_nul(b"\0").unwrap();
-    /// assert_eq!(cstr.count_bytes(), 0);
+    /// assert_eq!(c"foo".count_bytes(), 3);
+    /// assert_eq!(c"".count_bytes(), 0);
     /// ```
     #[inline]
     #[must_use]
@@ -533,19 +528,8 @@ impl CStr {
     /// # Examples
     ///
     /// ```
-    /// use std::ffi::CStr;
-    /// # use std::ffi::FromBytesWithNulError;
-    ///
-    /// # fn main() { test().unwrap(); }
-    /// # fn test() -> Result<(), FromBytesWithNulError> {
-    /// let cstr = CStr::from_bytes_with_nul(b"foo\0")?;
-    /// assert!(!cstr.is_empty());
-    ///
-    /// let empty_cstr = CStr::from_bytes_with_nul(b"\0")?;
-    /// assert!(empty_cstr.is_empty());
+    /// assert!(!c"foo".is_empty());
     /// assert!(c"".is_empty());
-    /// # Ok(())
-    /// # }
     /// ```
     #[inline]
     #[stable(feature = "cstr_is_empty", since = "1.71.0")]
@@ -569,10 +553,7 @@ impl CStr {
     /// # Examples
     ///
     /// ```
-    /// use std::ffi::CStr;
-    ///
-    /// let cstr = CStr::from_bytes_with_nul(b"foo\0").expect("CStr::from_bytes_with_nul failed");
-    /// assert_eq!(cstr.to_bytes(), b"foo");
+    /// assert_eq!(c"foo".to_bytes(), b"foo");
     /// ```
     #[inline]
     #[must_use = "this returns the result of the operation, \
@@ -598,10 +579,7 @@ impl CStr {
     /// # Examples
     ///
     /// ```
-    /// use std::ffi::CStr;
-    ///
-    /// let cstr = CStr::from_bytes_with_nul(b"foo\0").expect("CStr::from_bytes_with_nul failed");
-    /// assert_eq!(cstr.to_bytes_with_nul(), b"foo\0");
+    /// assert_eq!(c"foo".to_bytes_with_nul(), b"foo\0");
     /// ```
     #[inline]
     #[must_use = "this returns the result of the operation, \
@@ -623,10 +601,8 @@ impl CStr {
     ///
     /// ```
     /// #![feature(cstr_bytes)]
-    /// use std::ffi::CStr;
     ///
-    /// let cstr = CStr::from_bytes_with_nul(b"foo\0").expect("CStr::from_bytes_with_nul failed");
-    /// assert!(cstr.bytes().eq(*b"foo"));
+    /// assert!(c"foo".bytes().eq(*b"foo"));
     /// ```
     #[inline]
     #[unstable(feature = "cstr_bytes", issue = "112115")]
@@ -645,10 +621,7 @@ impl CStr {
     /// # Examples
     ///
     /// ```
-    /// use std::ffi::CStr;
-    ///
-    /// let cstr = CStr::from_bytes_with_nul(b"foo\0").expect("CStr::from_bytes_with_nul failed");
-    /// assert_eq!(cstr.to_str(), Ok("foo"));
+    /// assert_eq!(c"foo".to_str(), Ok("foo"));
     /// ```
     #[stable(feature = "cstr_to_str", since = "1.4.0")]
     #[rustc_const_stable(feature = "const_cstr_methods", since = "1.72.0")]
diff --git a/library/core/src/fmt/mod.rs b/library/core/src/fmt/mod.rs
index 4f7f8a5b84d..5978cb660f6 100644
--- a/library/core/src/fmt/mod.rs
+++ b/library/core/src/fmt/mod.rs
@@ -856,10 +856,10 @@ impl Display for Arguments<'_> {
     on(
         crate_local,
         label = "`{Self}` cannot be formatted using `{{:?}}`",
-        note = "add `#[derive(Debug)]` to `{Self}` or manually `impl {Debug} for {Self}`"
+        note = "add `#[derive(Debug)]` to `{Self}` or manually `impl {This} for {Self}`"
     ),
-    message = "`{Self}` doesn't implement `{Debug}`",
-    label = "`{Self}` cannot be formatted using `{{:?}}` because it doesn't implement `{Debug}`"
+    message = "`{Self}` doesn't implement `{This}`",
+    label = "`{Self}` cannot be formatted using `{{:?}}` because it doesn't implement `{This}`"
 )]
 #[doc(alias = "{:?}")]
 #[rustc_diagnostic_item = "Debug"]
@@ -969,12 +969,12 @@ pub use macros::Debug;
 /// ```
 #[rustc_on_unimplemented(
     on(
-        any(_Self = "std::path::Path", _Self = "std::path::PathBuf"),
+        any(Self = "std::path::Path", Self = "std::path::PathBuf"),
         label = "`{Self}` cannot be formatted with the default formatter; call `.display()` on it",
         note = "call `.display()` or `.to_string_lossy()` to safely print paths, \
                 as they may contain non-Unicode data"
     ),
-    message = "`{Self}` doesn't implement `{Display}`",
+    message = "`{Self}` doesn't implement `{This}`",
     label = "`{Self}` cannot be formatted with the default formatter",
     note = "in format strings you may be able to use `{{:?}}` (or {{:#?}} for pretty-print) instead"
 )]
diff --git a/library/core/src/hint.rs b/library/core/src/hint.rs
index 6eefb304689..8ea9de7e9e5 100644
--- a/library/core/src/hint.rs
+++ b/library/core/src/hint.rs
@@ -231,7 +231,7 @@ pub const unsafe fn assert_unchecked(cond: bool) {
 ///
 /// # Examples
 ///
-/// ```
+/// ```ignore-wasm
 /// use std::sync::atomic::{AtomicBool, Ordering};
 /// use std::sync::Arc;
 /// use std::{hint, thread};
diff --git a/library/core/src/intrinsics/mod.rs b/library/core/src/intrinsics/mod.rs
index 23bafa778bc..e9fa3b1b3f6 100644
--- a/library/core/src/intrinsics/mod.rs
+++ b/library/core/src/intrinsics/mod.rs
@@ -2296,12 +2296,6 @@ pub fn round_ties_even_f16(x: f16) -> f16;
 #[rustc_nounwind]
 pub fn round_ties_even_f32(x: f32) -> f32;
 
-/// Provided for compatibility with stdarch. DO NOT USE.
-#[inline(always)]
-pub unsafe fn rintf32(x: f32) -> f32 {
-    round_ties_even_f32(x)
-}
-
 /// Returns the nearest integer to an `f64`. Rounds half-way cases to the number with an even
 /// least significant digit.
 ///
@@ -2311,12 +2305,6 @@ pub unsafe fn rintf32(x: f32) -> f32 {
 #[rustc_nounwind]
 pub fn round_ties_even_f64(x: f64) -> f64;
 
-/// Provided for compatibility with stdarch. DO NOT USE.
-#[inline(always)]
-pub unsafe fn rintf64(x: f64) -> f64 {
-    round_ties_even_f64(x)
-}
-
 /// Returns the nearest integer to an `f128`. Rounds half-way cases to the number with an even
 /// least significant digit.
 ///
diff --git a/library/core/src/iter/traits/collect.rs b/library/core/src/iter/traits/collect.rs
index 97bb21c8a36..3bc9cff8072 100644
--- a/library/core/src/iter/traits/collect.rs
+++ b/library/core/src/iter/traits/collect.rs
@@ -97,32 +97,32 @@ use super::TrustedLen;
 #[stable(feature = "rust1", since = "1.0.0")]
 #[rustc_on_unimplemented(
     on(
-        _Self = "&[{A}]",
+        Self = "&[{A}]",
         message = "a slice of type `{Self}` cannot be built since we need to store the elements somewhere",
         label = "try explicitly collecting into a `Vec<{A}>`",
     ),
     on(
-        all(A = "{integer}", any(_Self = "&[{integral}]",)),
+        all(A = "{integer}", any(Self = "&[{integral}]",)),
         message = "a slice of type `{Self}` cannot be built since we need to store the elements somewhere",
         label = "try explicitly collecting into a `Vec<{A}>`",
     ),
     on(
-        _Self = "[{A}]",
+        Self = "[{A}]",
         message = "a slice of type `{Self}` cannot be built since `{Self}` has no definite size",
         label = "try explicitly collecting into a `Vec<{A}>`",
     ),
     on(
-        all(A = "{integer}", any(_Self = "[{integral}]",)),
+        all(A = "{integer}", any(Self = "[{integral}]",)),
         message = "a slice of type `{Self}` cannot be built since `{Self}` has no definite size",
         label = "try explicitly collecting into a `Vec<{A}>`",
     ),
     on(
-        _Self = "[{A}; _]",
+        Self = "[{A}; _]",
         message = "an array of type `{Self}` cannot be built directly from an iterator",
         label = "try collecting into a `Vec<{A}>`, then using `.try_into()`",
     ),
     on(
-        all(A = "{integer}", any(_Self = "[{integral}; _]",)),
+        all(A = "{integer}", any(Self = "[{integral}; _]",)),
         message = "an array of type `{Self}` cannot be built directly from an iterator",
         label = "try collecting into a `Vec<{A}>`, then using `.try_into()`",
     ),
@@ -239,41 +239,38 @@ pub trait FromIterator<A>: Sized {
 #[rustc_diagnostic_item = "IntoIterator"]
 #[rustc_on_unimplemented(
     on(
-        _Self = "core::ops::range::RangeTo<Idx>",
+        Self = "core::ops::range::RangeTo<Idx>",
         label = "if you meant to iterate until a value, add a starting value",
         note = "`..end` is a `RangeTo`, which cannot be iterated on; you might have meant to have a \
               bounded `Range`: `0..end`"
     ),
     on(
-        _Self = "core::ops::range::RangeToInclusive<Idx>",
+        Self = "core::ops::range::RangeToInclusive<Idx>",
         label = "if you meant to iterate until a value (including it), add a starting value",
         note = "`..=end` is a `RangeToInclusive`, which cannot be iterated on; you might have meant \
               to have a bounded `RangeInclusive`: `0..=end`"
     ),
     on(
-        _Self = "[]",
+        Self = "[]",
         label = "`{Self}` is not an iterator; try calling `.into_iter()` or `.iter()`"
     ),
-    on(_Self = "&[]", label = "`{Self}` is not an iterator; try calling `.iter()`"),
+    on(Self = "&[]", label = "`{Self}` is not an iterator; try calling `.iter()`"),
     on(
-        _Self = "alloc::vec::Vec<T, A>",
+        Self = "alloc::vec::Vec<T, A>",
         label = "`{Self}` is not an iterator; try calling `.into_iter()` or `.iter()`"
     ),
+    on(Self = "&str", label = "`{Self}` is not an iterator; try calling `.chars()` or `.bytes()`"),
     on(
-        _Self = "&str",
+        Self = "alloc::string::String",
         label = "`{Self}` is not an iterator; try calling `.chars()` or `.bytes()`"
     ),
     on(
-        _Self = "alloc::string::String",
-        label = "`{Self}` is not an iterator; try calling `.chars()` or `.bytes()`"
-    ),
-    on(
-        _Self = "{integral}",
+        Self = "{integral}",
         note = "if you want to iterate between `start` until a value `end`, use the exclusive range \
               syntax `start..end` or the inclusive range syntax `start..=end`"
     ),
     on(
-        _Self = "{float}",
+        Self = "{float}",
         note = "if you want to iterate between `start` until a value `end`, use the exclusive range \
               syntax `start..end` or the inclusive range syntax `start..=end`"
     ),
diff --git a/library/core/src/iter/traits/iterator.rs b/library/core/src/iter/traits/iterator.rs
index d1e71f0e60f..cf85bdb1352 100644
--- a/library/core/src/iter/traits/iterator.rs
+++ b/library/core/src/iter/traits/iterator.rs
@@ -22,11 +22,11 @@ fn _assert_is_dyn_compatible(_: &dyn Iterator<Item = ()>) {}
 #[stable(feature = "rust1", since = "1.0.0")]
 #[rustc_on_unimplemented(
     on(
-        _Self = "core::ops::range::RangeTo<Idx>",
+        Self = "core::ops::range::RangeTo<Idx>",
         note = "you might have meant to use a bounded `Range`"
     ),
     on(
-        _Self = "core::ops::range::RangeToInclusive<Idx>",
+        Self = "core::ops::range::RangeToInclusive<Idx>",
         note = "you might have meant to use a bounded `RangeInclusive`"
     ),
     label = "`{Self}` is not an iterator",
diff --git a/library/core/src/lib.rs b/library/core/src/lib.rs
index b76213fdd41..c49513f7a6d 100644
--- a/library/core/src/lib.rs
+++ b/library/core/src/lib.rs
@@ -158,7 +158,6 @@
 #![feature(intra_doc_pointers)]
 #![feature(intrinsics)]
 #![feature(lang_items)]
-#![feature(let_chains)]
 #![feature(link_llvm_intrinsics)]
 #![feature(macro_metavar_expr)]
 #![feature(marker_trait_attr)]
diff --git a/library/core/src/marker.rs b/library/core/src/marker.rs
index f33b8d188d8..700fb0f386e 100644
--- a/library/core/src/marker.rs
+++ b/library/core/src/marker.rs
@@ -550,72 +550,72 @@ pub trait BikeshedGuaranteedNoDrop {}
 #[lang = "sync"]
 #[rustc_on_unimplemented(
     on(
-        _Self = "core::cell::once::OnceCell<T>",
+        Self = "core::cell::once::OnceCell<T>",
         note = "if you want to do aliasing and mutation between multiple threads, use `std::sync::OnceLock` instead"
     ),
     on(
-        _Self = "core::cell::Cell<u8>",
+        Self = "core::cell::Cell<u8>",
         note = "if you want to do aliasing and mutation between multiple threads, use `std::sync::RwLock` or `std::sync::atomic::AtomicU8` instead",
     ),
     on(
-        _Self = "core::cell::Cell<u16>",
+        Self = "core::cell::Cell<u16>",
         note = "if you want to do aliasing and mutation between multiple threads, use `std::sync::RwLock` or `std::sync::atomic::AtomicU16` instead",
     ),
     on(
-        _Self = "core::cell::Cell<u32>",
+        Self = "core::cell::Cell<u32>",
         note = "if you want to do aliasing and mutation between multiple threads, use `std::sync::RwLock` or `std::sync::atomic::AtomicU32` instead",
     ),
     on(
-        _Self = "core::cell::Cell<u64>",
+        Self = "core::cell::Cell<u64>",
         note = "if you want to do aliasing and mutation between multiple threads, use `std::sync::RwLock` or `std::sync::atomic::AtomicU64` instead",
     ),
     on(
-        _Self = "core::cell::Cell<usize>",
+        Self = "core::cell::Cell<usize>",
         note = "if you want to do aliasing and mutation between multiple threads, use `std::sync::RwLock` or `std::sync::atomic::AtomicUsize` instead",
     ),
     on(
-        _Self = "core::cell::Cell<i8>",
+        Self = "core::cell::Cell<i8>",
         note = "if you want to do aliasing and mutation between multiple threads, use `std::sync::RwLock` or `std::sync::atomic::AtomicI8` instead",
     ),
     on(
-        _Self = "core::cell::Cell<i16>",
+        Self = "core::cell::Cell<i16>",
         note = "if you want to do aliasing and mutation between multiple threads, use `std::sync::RwLock` or `std::sync::atomic::AtomicI16` instead",
     ),
     on(
-        _Self = "core::cell::Cell<i32>",
+        Self = "core::cell::Cell<i32>",
         note = "if you want to do aliasing and mutation between multiple threads, use `std::sync::RwLock` or `std::sync::atomic::AtomicI32` instead",
     ),
     on(
-        _Self = "core::cell::Cell<i64>",
+        Self = "core::cell::Cell<i64>",
         note = "if you want to do aliasing and mutation between multiple threads, use `std::sync::RwLock` or `std::sync::atomic::AtomicI64` instead",
     ),
     on(
-        _Self = "core::cell::Cell<isize>",
+        Self = "core::cell::Cell<isize>",
         note = "if you want to do aliasing and mutation between multiple threads, use `std::sync::RwLock` or `std::sync::atomic::AtomicIsize` instead",
     ),
     on(
-        _Self = "core::cell::Cell<bool>",
+        Self = "core::cell::Cell<bool>",
         note = "if you want to do aliasing and mutation between multiple threads, use `std::sync::RwLock` or `std::sync::atomic::AtomicBool` instead",
     ),
     on(
         all(
-            _Self = "core::cell::Cell<T>",
-            not(_Self = "core::cell::Cell<u8>"),
-            not(_Self = "core::cell::Cell<u16>"),
-            not(_Self = "core::cell::Cell<u32>"),
-            not(_Self = "core::cell::Cell<u64>"),
-            not(_Self = "core::cell::Cell<usize>"),
-            not(_Self = "core::cell::Cell<i8>"),
-            not(_Self = "core::cell::Cell<i16>"),
-            not(_Self = "core::cell::Cell<i32>"),
-            not(_Self = "core::cell::Cell<i64>"),
-            not(_Self = "core::cell::Cell<isize>"),
-            not(_Self = "core::cell::Cell<bool>")
+            Self = "core::cell::Cell<T>",
+            not(Self = "core::cell::Cell<u8>"),
+            not(Self = "core::cell::Cell<u16>"),
+            not(Self = "core::cell::Cell<u32>"),
+            not(Self = "core::cell::Cell<u64>"),
+            not(Self = "core::cell::Cell<usize>"),
+            not(Self = "core::cell::Cell<i8>"),
+            not(Self = "core::cell::Cell<i16>"),
+            not(Self = "core::cell::Cell<i32>"),
+            not(Self = "core::cell::Cell<i64>"),
+            not(Self = "core::cell::Cell<isize>"),
+            not(Self = "core::cell::Cell<bool>")
         ),
         note = "if you want to do aliasing and mutation between multiple threads, use `std::sync::RwLock`",
     ),
     on(
-        _Self = "core::cell::RefCell<T>",
+        Self = "core::cell::RefCell<T>",
         note = "if you want to do aliasing and mutation between multiple threads, use `std::sync::RwLock` instead",
     ),
     message = "`{Self}` cannot be shared between threads safely",
diff --git a/library/core/src/ops/arith.rs b/library/core/src/ops/arith.rs
index 54d79beca95..098ce4531f0 100644
--- a/library/core/src/ops/arith.rs
+++ b/library/core/src/ops/arith.rs
@@ -67,8 +67,8 @@
 #[stable(feature = "rust1", since = "1.0.0")]
 #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
 #[rustc_on_unimplemented(
-    on(all(_Self = "{integer}", Rhs = "{float}"), message = "cannot add a float to an integer",),
-    on(all(_Self = "{float}", Rhs = "{integer}"), message = "cannot add an integer to a float",),
+    on(all(Self = "{integer}", Rhs = "{float}"), message = "cannot add a float to an integer",),
+    on(all(Self = "{float}", Rhs = "{integer}"), message = "cannot add an integer to a float",),
     message = "cannot add `{Rhs}` to `{Self}`",
     label = "no implementation for `{Self} + {Rhs}`",
     append_const_msg
diff --git a/library/core/src/ops/function.rs b/library/core/src/ops/function.rs
index e9014458b48..df48c104410 100644
--- a/library/core/src/ops/function.rs
+++ b/library/core/src/ops/function.rs
@@ -62,7 +62,7 @@ use crate::marker::Tuple;
         note = "wrap the `{Self}` in a closure with no arguments: `|| {{ /* code */ }}`"
     ),
     on(
-        _Self = "unsafe fn",
+        Self = "unsafe fn",
         note = "unsafe function cannot be called generically without an unsafe block",
         // SAFETY: tidy is not smart enough to tell that the below unsafe block is a string
         label = "call the function in a closure: `|| unsafe {{ /* code */ }}`"
@@ -149,7 +149,7 @@ pub trait Fn<Args: Tuple>: FnMut<Args> {
         note = "wrap the `{Self}` in a closure with no arguments: `|| {{ /* code */ }}`"
     ),
     on(
-        _Self = "unsafe fn",
+        Self = "unsafe fn",
         note = "unsafe function cannot be called generically without an unsafe block",
         // SAFETY: tidy is not smart enough to tell that the below unsafe block is a string
         label = "call the function in a closure: `|| unsafe {{ /* code */ }}`"
@@ -228,7 +228,7 @@ pub trait FnMut<Args: Tuple>: FnOnce<Args> {
         note = "wrap the `{Self}` in a closure with no arguments: `|| {{ /* code */ }}`"
     ),
     on(
-        _Self = "unsafe fn",
+        Self = "unsafe fn",
         note = "unsafe function cannot be called generically without an unsafe block",
         // SAFETY: tidy is not smart enough to tell that the below unsafe block is a string
         label = "call the function in a closure: `|| unsafe {{ /* code */ }}`"
diff --git a/library/core/src/ops/index.rs b/library/core/src/ops/index.rs
index 46e19bed43a..8092fa9eb2f 100644
--- a/library/core/src/ops/index.rs
+++ b/library/core/src/ops/index.rs
@@ -144,17 +144,17 @@ pub trait Index<Idx: ?Sized> {
 #[lang = "index_mut"]
 #[rustc_on_unimplemented(
     on(
-        _Self = "&str",
+        Self = "&str",
         note = "you can use `.chars().nth()` or `.bytes().nth()`
 see chapter in The Book <https://doc.rust-lang.org/book/ch08-02-strings.html#indexing-into-strings>"
     ),
     on(
-        _Self = "str",
+        Self = "str",
         note = "you can use `.chars().nth()` or `.bytes().nth()`
 see chapter in The Book <https://doc.rust-lang.org/book/ch08-02-strings.html#indexing-into-strings>"
     ),
     on(
-        _Self = "alloc::string::String",
+        Self = "alloc::string::String",
         note = "you can use `.chars().nth()` or `.bytes().nth()`
 see chapter in The Book <https://doc.rust-lang.org/book/ch08-02-strings.html#indexing-into-strings>"
     ),
diff --git a/library/core/src/ops/try_trait.rs b/library/core/src/ops/try_trait.rs
index 3ba2957526f..bac8ffb074b 100644
--- a/library/core/src/ops/try_trait.rs
+++ b/library/core/src/ops/try_trait.rs
@@ -117,12 +117,12 @@ use crate::ops::ControlFlow;
     on(
         all(from_desugaring = "TryBlock"),
         message = "a `try` block must return `Result` or `Option` \
-                    (or another type that implements `{Try}`)",
+                    (or another type that implements `{This}`)",
         label = "could not wrap the final value of the block as `{Self}` doesn't implement `Try`",
     ),
     on(
         all(from_desugaring = "QuestionMark"),
-        message = "the `?` operator can only be applied to values that implement `{Try}`",
+        message = "the `?` operator can only be applied to values that implement `{This}`",
         label = "the `?` operator cannot be applied to type `{Self}`"
     )
 )]
@@ -226,7 +226,7 @@ pub trait Try: FromResidual {
     on(
         all(
             from_desugaring = "QuestionMark",
-            _Self = "core::result::Result<T, E>",
+            Self = "core::result::Result<T, E>",
             R = "core::option::Option<core::convert::Infallible>",
         ),
         message = "the `?` operator can only be used on `Result`s, not `Option`s, \
@@ -237,7 +237,7 @@ pub trait Try: FromResidual {
     on(
         all(
             from_desugaring = "QuestionMark",
-            _Self = "core::result::Result<T, E>",
+            Self = "core::result::Result<T, E>",
         ),
         // There's a special error message in the trait selection code for
         // `From` in `?`, so this is not shown for result-in-result errors,
@@ -250,7 +250,7 @@ pub trait Try: FromResidual {
     on(
         all(
             from_desugaring = "QuestionMark",
-            _Self = "core::option::Option<T>",
+            Self = "core::option::Option<T>",
             R = "core::result::Result<T, E>",
         ),
         message = "the `?` operator can only be used on `Option`s, not `Result`s, \
@@ -261,7 +261,7 @@ pub trait Try: FromResidual {
     on(
         all(
             from_desugaring = "QuestionMark",
-            _Self = "core::option::Option<T>",
+            Self = "core::option::Option<T>",
         ),
         // `Option`-in-`Option` always works, as there's only one possible
         // residual, so this can also be phrased strongly.
@@ -273,7 +273,7 @@ pub trait Try: FromResidual {
     on(
         all(
             from_desugaring = "QuestionMark",
-            _Self = "core::ops::control_flow::ControlFlow<B, C>",
+            Self = "core::ops::control_flow::ControlFlow<B, C>",
             R = "core::ops::control_flow::ControlFlow<B, C>",
         ),
         message = "the `?` operator in {ItemContext} that returns `ControlFlow<B, _>` \
@@ -285,7 +285,7 @@ pub trait Try: FromResidual {
     on(
         all(
             from_desugaring = "QuestionMark",
-            _Self = "core::ops::control_flow::ControlFlow<B, C>",
+            Self = "core::ops::control_flow::ControlFlow<B, C>",
             // `R` is not a `ControlFlow`, as that case was matched previously
         ),
         message = "the `?` operator can only be used on `ControlFlow`s \
@@ -297,7 +297,7 @@ pub trait Try: FromResidual {
         all(from_desugaring = "QuestionMark"),
         message = "the `?` operator can only be used in {ItemContext} \
                     that returns `Result` or `Option` \
-                    (or another type that implements `{FromResidual}`)",
+                    (or another type that implements `{This}`)",
         label = "cannot use the `?` operator in {ItemContext} that returns `{Self}`",
         parent_label = "this function should return `Result` or `Option` to accept `?`"
     ),
diff --git a/library/core/src/option.rs b/library/core/src/option.rs
index aed5a043c11..1d264b26076 100644
--- a/library/core/src/option.rs
+++ b/library/core/src/option.rs
@@ -120,20 +120,22 @@
 //!
 //! Rust guarantees to optimize the following types `T` such that
 //! [`Option<T>`] has the same size, alignment, and [function call ABI] as `T`. In some
-//! of these cases, Rust further guarantees that
-//! `transmute::<_, Option<T>>([0u8; size_of::<T>()])` is sound and
-//! produces `Option::<T>::None`. These cases are identified by the
-//! second column:
-//!
-//! | `T`                                                                 | `transmute::<_, Option<T>>([0u8; size_of::<T>()])` sound? |
-//! |---------------------------------------------------------------------|----------------------------------------------------------------------|
-//! | [`Box<U>`] (specifically, only `Box<U, Global>`)                    | when `U: Sized`                                                      |
-//! | `&U`                                                                | when `U: Sized`                                                      |
-//! | `&mut U`                                                            | when `U: Sized`                                                      |
-//! | `fn`, `extern "C" fn`[^extern_fn]                                   | always                                                               |
-//! | [`num::NonZero*`]                                                   | always                                                               |
-//! | [`ptr::NonNull<U>`]                                                 | when `U: Sized`                                                      |
-//! | `#[repr(transparent)]` struct around one of the types in this list. | when it holds for the inner type                                     |
+//! of these cases, Rust further guarantees the following:
+//! - `transmute::<_, Option<T>>([0u8; size_of::<T>()])` is sound and produces
+//!   `Option::<T>::None`
+//! - `transmute::<_, [u8; size_of::<T>()]>(Option::<T>::None)` is sound and produces
+//!   `[0u8; size_of::<T>()]`
+//! These cases are identified by the second column:
+//!
+//! | `T`                                                                 | Transmuting between `[0u8; size_of::<T>()]` and `Option::<T>::None` sound? |
+//! |---------------------------------------------------------------------|----------------------------------------------------------------------------|
+//! | [`Box<U>`] (specifically, only `Box<U, Global>`)                    | when `U: Sized`                                                            |
+//! | `&U`                                                                | when `U: Sized`                                                            |
+//! | `&mut U`                                                            | when `U: Sized`                                                            |
+//! | `fn`, `extern "C" fn`[^extern_fn]                                   | always                                                                     |
+//! | [`num::NonZero*`]                                                   | always                                                                     |
+//! | [`ptr::NonNull<U>`]                                                 | when `U: Sized`                                                            |
+//! | `#[repr(transparent)]` struct around one of the types in this list. | when it holds for the inner type                                           |
 //!
 //! [^extern_fn]: this remains true for any argument/return types and any other ABI: `extern "abi" fn` (_e.g._, `extern "system" fn`)
 //!
diff --git a/library/core/src/ptr/const_ptr.rs b/library/core/src/ptr/const_ptr.rs
index f6109cafe86..19ed7599a51 100644
--- a/library/core/src/ptr/const_ptr.rs
+++ b/library/core/src/ptr/const_ptr.rs
@@ -76,15 +76,13 @@ impl<T: ?Sized> *const T {
     /// ```rust
     /// #![feature(pointer_try_cast_aligned)]
     ///
-    /// let aligned: *const u8 = 0x1000 as _;
+    /// let x = 0u64;
     ///
-    /// // i32 has at most 4-byte alignment, so this will succeed
-    /// assert!(aligned.try_cast_aligned::<i32>().is_some());
+    /// let aligned: *const u64 = &x;
+    /// let unaligned = unsafe { aligned.byte_add(1) };
     ///
-    /// let unaligned: *const u8 = 0x1001 as _;
-    ///
-    /// // i32 has at least 2-byte alignment, so this will fail
-    /// assert!(unaligned.try_cast_aligned::<i32>().is_none());
+    /// assert!(aligned.try_cast_aligned::<u32>().is_some());
+    /// assert!(unaligned.try_cast_aligned::<u32>().is_none());
     /// ```
     #[unstable(feature = "pointer_try_cast_aligned", issue = "141221")]
     #[must_use = "this returns the result of the operation, \
diff --git a/library/core/src/ptr/mut_ptr.rs b/library/core/src/ptr/mut_ptr.rs
index 2662a4fdc31..53aa3ab4938 100644
--- a/library/core/src/ptr/mut_ptr.rs
+++ b/library/core/src/ptr/mut_ptr.rs
@@ -58,15 +58,13 @@ impl<T: ?Sized> *mut T {
     /// ```rust
     /// #![feature(pointer_try_cast_aligned)]
     ///
-    /// let aligned: *mut u8 = 0x1000 as _;
+    /// let mut x = 0u64;
     ///
-    /// // i32 has at most 4-byte alignment, so this will succeed
-    /// assert!(aligned.try_cast_aligned::<i32>().is_some());
+    /// let aligned: *mut u64 = &mut x;
+    /// let unaligned = unsafe { aligned.byte_add(1) };
     ///
-    /// let unaligned: *mut u8 = 0x1001 as _;
-    ///
-    /// // i32 has at least 2-byte alignment, so this will fail
-    /// assert!(unaligned.try_cast_aligned::<i32>().is_none());
+    /// assert!(aligned.try_cast_aligned::<u32>().is_some());
+    /// assert!(unaligned.try_cast_aligned::<u32>().is_none());
     /// ```
     #[unstable(feature = "pointer_try_cast_aligned", issue = "141221")]
     #[must_use = "this returns the result of the operation, \
diff --git a/library/core/src/ptr/non_null.rs b/library/core/src/ptr/non_null.rs
index bb344c6a0d3..7c9b898f8e9 100644
--- a/library/core/src/ptr/non_null.rs
+++ b/library/core/src/ptr/non_null.rs
@@ -501,15 +501,13 @@ impl<T: ?Sized> NonNull<T> {
     /// #![feature(pointer_try_cast_aligned)]
     /// use std::ptr::NonNull;
     ///
-    /// let aligned: NonNull<u8> = NonNull::new(0x1000 as _).unwrap();
+    /// let mut x = 0u64;
     ///
-    /// // i32 has at most 4-byte alignment, so this will succeed
-    /// assert!(aligned.try_cast_aligned::<i32>().is_some());
+    /// let aligned = NonNull::from_mut(&mut x);
+    /// let unaligned = unsafe { aligned.byte_add(1) };
     ///
-    /// let unaligned: NonNull<u8> = NonNull::new(0x1001 as _).unwrap();
-    ///
-    /// // i32 has at least 2-byte alignment, so this will fail
-    /// assert!(unaligned.try_cast_aligned::<i32>().is_none());
+    /// assert!(aligned.try_cast_aligned::<u32>().is_some());
+    /// assert!(unaligned.try_cast_aligned::<u32>().is_none());
     /// ```
     #[unstable(feature = "pointer_try_cast_aligned", issue = "141221")]
     #[must_use = "this returns the result of the operation, \
diff --git a/library/core/src/slice/index.rs b/library/core/src/slice/index.rs
index aafa19c0dd3..409bad9f061 100644
--- a/library/core/src/slice/index.rs
+++ b/library/core/src/slice/index.rs
@@ -161,7 +161,7 @@ mod private_slice_index {
 #[rustc_on_unimplemented(
     on(T = "str", label = "string indices are ranges of `usize`",),
     on(
-        all(any(T = "str", T = "&str", T = "alloc::string::String"), _Self = "{integer}"),
+        all(any(T = "str", T = "&str", T = "alloc::string::String"), Self = "{integer}"),
         note = "you can use `.chars().nth()` or `.bytes().nth()`\n\
                 for more information, see chapter 8 in The Book: \
                 <https://doc.rust-lang.org/book/ch08-02-strings.html#indexing-into-strings>"
diff --git a/library/core/src/sync/atomic.rs b/library/core/src/sync/atomic.rs
index 84c7f1aafe1..bd5a58d74ba 100644
--- a/library/core/src/sync/atomic.rs
+++ b/library/core/src/sync/atomic.rs
@@ -193,7 +193,7 @@
 //!
 //! A simple spinlock:
 //!
-//! ```
+//! ```ignore-wasm
 //! use std::sync::Arc;
 //! use std::sync::atomic::{AtomicUsize, Ordering};
 //! use std::{hint, thread};
@@ -622,7 +622,7 @@ impl AtomicBool {
     ///
     /// # Examples
     ///
-    /// ```
+    /// ```ignore-wasm
     /// #![feature(atomic_from_mut)]
     /// use std::sync::atomic::{AtomicBool, Ordering};
     ///
@@ -653,7 +653,7 @@ impl AtomicBool {
     ///
     /// # Examples
     ///
-    /// ```
+    /// ```rust,ignore-wasm
     /// #![feature(atomic_from_mut)]
     /// use std::sync::atomic::{AtomicBool, Ordering};
     ///
@@ -1548,7 +1548,7 @@ impl<T> AtomicPtr<T> {
     ///
     /// # Examples
     ///
-    /// ```
+    /// ```ignore-wasm
     /// #![feature(atomic_from_mut)]
     /// use std::ptr::null_mut;
     /// use std::sync::atomic::{AtomicPtr, Ordering};
@@ -1585,7 +1585,7 @@ impl<T> AtomicPtr<T> {
     ///
     /// # Examples
     ///
-    /// ```
+    /// ```ignore-wasm
     /// #![feature(atomic_from_mut)]
     /// use std::ptr::null_mut;
     /// use std::sync::atomic::{AtomicPtr, Ordering};
@@ -2692,7 +2692,7 @@ macro_rules! atomic_int {
             ///
             /// # Examples
             ///
-            /// ```
+            /// ```ignore-wasm
             /// #![feature(atomic_from_mut)]
             #[doc = concat!($extra_feature, "use std::sync::atomic::{", stringify!($atomic_type), ", Ordering};")]
             ///
@@ -2725,7 +2725,7 @@ macro_rules! atomic_int {
             ///
             /// # Examples
             ///
-            /// ```
+            /// ```ignore-wasm
             /// #![feature(atomic_from_mut)]
             #[doc = concat!($extra_feature, "use std::sync::atomic::{", stringify!($atomic_type), ", Ordering};")]
             ///