Auto merge of #66021 - tmandry:rollup-y13l6n9, r=tmandry

Rollup of 16 pull requests

Successful merges:

 - #65112 (Add lint and tests for unnecessary parens around types)
 - #65470 (Don't hide ICEs from previous incremental compiles)
 - #65471 (Add long error explanation for E0578)
 - #65857 (rustdoc: Resolve module-level doc references more locally)
 - #65902 (Make ItemContext available for better diagnositcs)
 - #65914 (Use structured suggestion for unnecessary bounds in type aliases)
 - #65946 (Make `promote_consts` emit the errors when required promotion fails)
 - #65960 (doc: reword iter module example and mention other methods)
 - #65963 (update submodules to rust-lang)
 - #65972 (Fix libunwind build: Define __LITTLE_ENDIAN__ for LE targets)
 - #65977 (Fix incorrect diagnostics for expected type in E0271 with an associated type)
 - #65995 (Add error code E0743 for "C-variadic has been used on a non-foreign function")
 - #65997 (Fix outdated rustdoc of Once::init_locking function)
 - #66002 (Stabilize float_to_from_bytes feature)
 - #66005 (vxWorks: remove code related unix socket)
 - #66018 (Revert PR 64324: dylibs export generics again (for now))

Failed merges:

r? @ghost

4 files changed, 41 insertions, 47 deletions

diff --git a/src/libcore/iter/mod.rs b/src/libcore/iter/mod.rs
index aba8e84d58b..fac6ff0f06b 100644
--- a/src/libcore/iter/mod.rs
+++ b/src/libcore/iter/mod.rs
@@ -118,26 +118,16 @@
 //!
 //! let mut counter = Counter::new();
 //!
-//! let x = counter.next().unwrap();
-//! println!("{}", x);
-//!
-//! let x = counter.next().unwrap();
-//! println!("{}", x);
-//!
-//! let x = counter.next().unwrap();
-//! println!("{}", x);
-//!
-//! let x = counter.next().unwrap();
-//! println!("{}", x);
-//!
-//! let x = counter.next().unwrap();
-//! println!("{}", x);
+//! assert_eq!(counter.next(), Some(1));
+//! assert_eq!(counter.next(), Some(2));
+//! assert_eq!(counter.next(), Some(3));
+//! assert_eq!(counter.next(), Some(4));
+//! assert_eq!(counter.next(), Some(5));
+//! assert_eq!(counter.next(), None);
 //! ```
 //!
-//! This will print `1` through `5`, each on their own line.
-//!
-//! Calling `next()` this way gets repetitive. Rust has a construct which can
-//! call `next()` on your iterator, until it reaches `None`. Let's go over that
+//! Calling [`next`] this way gets repetitive. Rust has a construct which can
+//! call [`next`] on your iterator, until it reaches `None`. Let's go over that
 //! next.
 //!
 //! Also note that `Iterator` provides a default implementation of methods such as `nth` and `fold`
@@ -253,20 +243,23 @@
 //! ```
 //!
 //! The idiomatic way to write a [`map`] for its side effects is to use a
-//! `for` loop instead:
+//! `for` loop or call the [`for_each`] method:
 //!
 //! ```
 //! let v = vec![1, 2, 3, 4, 5];
 //!
+//! v.iter().for_each(|x| println!("{}", x));
+//! // or
 //! for x in &v {
 //!     println!("{}", x);
 //! }
 //! ```
 //!
 //! [`map`]: trait.Iterator.html#method.map
+//! [`for_each`]: trait.Iterator.html#method.for_each
 //!
-//! The two most common ways to evaluate an iterator are to use a `for` loop
-//! like this, or using the [`collect`] method to produce a new collection.
+//! Another common way to evaluate an iterator is to use the [`collect`]
+//! method to produce a new collection.
 //!
 //! [`collect`]: trait.Iterator.html#method.collect
 //!
diff --git a/src/libcore/num/f32.rs b/src/libcore/num/f32.rs
index 22e7573eca6..5730088c4d9 100644
--- a/src/libcore/num/f32.rs
+++ b/src/libcore/num/f32.rs
@@ -466,11 +466,10 @@ impl f32 {
     /// # Examples
     ///
     /// ```
-    /// #![feature(float_to_from_bytes)]
     /// let bytes = 12.5f32.to_be_bytes();
     /// assert_eq!(bytes, [0x41, 0x48, 0x00, 0x00]);
     /// ```
-    #[unstable(feature = "float_to_from_bytes", issue = "60446")]
+    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
     #[inline]
     pub fn to_be_bytes(self) -> [u8; 4] {
         self.to_bits().to_be_bytes()
@@ -482,11 +481,10 @@ impl f32 {
     /// # Examples
     ///
     /// ```
-    /// #![feature(float_to_from_bytes)]
     /// let bytes = 12.5f32.to_le_bytes();
     /// assert_eq!(bytes, [0x00, 0x00, 0x48, 0x41]);
     /// ```
-    #[unstable(feature = "float_to_from_bytes", issue = "60446")]
+    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
     #[inline]
     pub fn to_le_bytes(self) -> [u8; 4] {
         self.to_bits().to_le_bytes()
@@ -504,7 +502,6 @@ impl f32 {
     /// # Examples
     ///
     /// ```
-    /// #![feature(float_to_from_bytes)]
     /// let bytes = 12.5f32.to_ne_bytes();
     /// assert_eq!(
     ///     bytes,
@@ -515,7 +512,7 @@ impl f32 {
     ///     }
     /// );
     /// ```
-    #[unstable(feature = "float_to_from_bytes", issue = "60446")]
+    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
     #[inline]
     pub fn to_ne_bytes(self) -> [u8; 4] {
         self.to_bits().to_ne_bytes()
@@ -526,11 +523,10 @@ impl f32 {
     /// # Examples
     ///
     /// ```
-    /// #![feature(float_to_from_bytes)]
     /// let value = f32::from_be_bytes([0x41, 0x48, 0x00, 0x00]);
     /// assert_eq!(value, 12.5);
     /// ```
-    #[unstable(feature = "float_to_from_bytes", issue = "60446")]
+    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
     #[inline]
     pub fn from_be_bytes(bytes: [u8; 4]) -> Self {
         Self::from_bits(u32::from_be_bytes(bytes))
@@ -541,11 +537,10 @@ impl f32 {
     /// # Examples
     ///
     /// ```
-    /// #![feature(float_to_from_bytes)]
     /// let value = f32::from_le_bytes([0x00, 0x00, 0x48, 0x41]);
     /// assert_eq!(value, 12.5);
     /// ```
-    #[unstable(feature = "float_to_from_bytes", issue = "60446")]
+    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
     #[inline]
     pub fn from_le_bytes(bytes: [u8; 4]) -> Self {
         Self::from_bits(u32::from_le_bytes(bytes))
@@ -563,7 +558,6 @@ impl f32 {
     /// # Examples
     ///
     /// ```
-    /// #![feature(float_to_from_bytes)]
     /// let value = f32::from_ne_bytes(if cfg!(target_endian = "big") {
     ///     [0x41, 0x48, 0x00, 0x00]
     /// } else {
@@ -571,7 +565,7 @@ impl f32 {
     /// });
     /// assert_eq!(value, 12.5);
     /// ```
-    #[unstable(feature = "float_to_from_bytes", issue = "60446")]
+    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
     #[inline]
     pub fn from_ne_bytes(bytes: [u8; 4]) -> Self {
         Self::from_bits(u32::from_ne_bytes(bytes))
diff --git a/src/libcore/num/f64.rs b/src/libcore/num/f64.rs
index bbe1d040780..2bdeda340dc 100644
--- a/src/libcore/num/f64.rs
+++ b/src/libcore/num/f64.rs
@@ -479,11 +479,10 @@ impl f64 {
     /// # Examples
     ///
     /// ```
-    /// #![feature(float_to_from_bytes)]
     /// let bytes = 12.5f64.to_be_bytes();
     /// assert_eq!(bytes, [0x40, 0x29, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00]);
     /// ```
-    #[unstable(feature = "float_to_from_bytes", issue = "60446")]
+    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
     #[inline]
     pub fn to_be_bytes(self) -> [u8; 8] {
         self.to_bits().to_be_bytes()
@@ -495,11 +494,10 @@ impl f64 {
     /// # Examples
     ///
     /// ```
-    /// #![feature(float_to_from_bytes)]
     /// let bytes = 12.5f64.to_le_bytes();
     /// assert_eq!(bytes, [0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x29, 0x40]);
     /// ```
-    #[unstable(feature = "float_to_from_bytes", issue = "60446")]
+    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
     #[inline]
     pub fn to_le_bytes(self) -> [u8; 8] {
         self.to_bits().to_le_bytes()
@@ -517,7 +515,6 @@ impl f64 {
     /// # Examples
     ///
     /// ```
-    /// #![feature(float_to_from_bytes)]
     /// let bytes = 12.5f64.to_ne_bytes();
     /// assert_eq!(
     ///     bytes,
@@ -528,7 +525,7 @@ impl f64 {
     ///     }
     /// );
     /// ```
-    #[unstable(feature = "float_to_from_bytes", issue = "60446")]
+    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
     #[inline]
     pub fn to_ne_bytes(self) -> [u8; 8] {
         self.to_bits().to_ne_bytes()
@@ -539,11 +536,10 @@ impl f64 {
     /// # Examples
     ///
     /// ```
-    /// #![feature(float_to_from_bytes)]
     /// let value = f64::from_be_bytes([0x40, 0x29, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00]);
     /// assert_eq!(value, 12.5);
     /// ```
-    #[unstable(feature = "float_to_from_bytes", issue = "60446")]
+    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
     #[inline]
     pub fn from_be_bytes(bytes: [u8; 8]) -> Self {
         Self::from_bits(u64::from_be_bytes(bytes))
@@ -554,11 +550,10 @@ impl f64 {
     /// # Examples
     ///
     /// ```
-    /// #![feature(float_to_from_bytes)]
     /// let value = f64::from_le_bytes([0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x29, 0x40]);
     /// assert_eq!(value, 12.5);
     /// ```
-    #[unstable(feature = "float_to_from_bytes", issue = "60446")]
+    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
     #[inline]
     pub fn from_le_bytes(bytes: [u8; 8]) -> Self {
         Self::from_bits(u64::from_le_bytes(bytes))
@@ -576,7 +571,6 @@ impl f64 {
     /// # Examples
     ///
     /// ```
-    /// #![feature(float_to_from_bytes)]
     /// let value = f64::from_ne_bytes(if cfg!(target_endian = "big") {
     ///     [0x40, 0x29, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00]
     /// } else {
@@ -584,7 +578,7 @@ impl f64 {
     /// });
     /// assert_eq!(value, 12.5);
     /// ```
-    #[unstable(feature = "float_to_from_bytes", issue = "60446")]
+    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
     #[inline]
     pub fn from_ne_bytes(bytes: [u8; 8]) -> Self {
         Self::from_bits(u64::from_ne_bytes(bytes))
diff --git a/src/libcore/ops/try.rs b/src/libcore/ops/try.rs
index 76fec1020f1..e8f35f8cf24 100644
--- a/src/libcore/ops/try.rs
+++ b/src/libcore/ops/try.rs
@@ -5,7 +5,7 @@
 /// extracting those success or failure values from an existing instance and
 /// creating a new instance from a success or failure value.
 #[unstable(feature = "try_trait", issue = "42327")]
-#[rustc_on_unimplemented(
+#[cfg_attr(bootstrap, rustc_on_unimplemented(
    on(all(
        any(from_method="from_error", from_method="from_ok"),
        from_desugaring="QuestionMark"),
@@ -17,7 +17,20 @@
       message="the `?` operator can only be applied to values \
                that implement `{Try}`",
       label="the `?` operator cannot be applied to type `{Self}`")
-)]
+))]
+#[cfg_attr(not(bootstrap), rustc_on_unimplemented(
+on(all(
+any(from_method="from_error", from_method="from_ok"),
+from_desugaring="QuestionMark"),
+message="the `?` operator can only be used in {ItemContext} \
+               that returns `Result` or `Option` \
+               (or another type that implements `{Try}`)",
+label="cannot use the `?` operator in {ItemContext} that returns `{Self}`"),
+on(all(from_method="into_result", from_desugaring="QuestionMark"),
+message="the `?` operator can only be applied to values \
+               that implement `{Try}`",
+label="the `?` operator cannot be applied to type `{Self}`")
+))]
 #[doc(alias = "?")]
 pub trait Try {
     /// The type of this value when viewed as successful.