Merge from rustc

Author: The Miri Cronjob Bot

alloc/src/collections/btree/map.rs

@@ -1416,18 +1416,18 @@ impl<K, V, A: Allocator + Clone> BTreeMap<K, V, A> {
     ///
     /// # Examples
     ///
-    /// Splitting a map into even and odd keys, reusing the original map:
-    ///
     /// ```
     /// #![feature(btree_extract_if)]
     /// use std::collections::BTreeMap;
     ///
+    /// // Splitting a map into even and odd keys, reusing the original map:
     /// let mut map: BTreeMap<i32, i32> = (0..8).map(|x| (x, x)).collect();
     /// let evens: BTreeMap<_, _> = map.extract_if(.., |k, _v| k % 2 == 0).collect();
     /// let odds = map;
     /// assert_eq!(evens.keys().copied().collect::<Vec<_>>(), [0, 2, 4, 6]);
     /// assert_eq!(odds.keys().copied().collect::<Vec<_>>(), [1, 3, 5, 7]);
     ///
+    /// // Splitting a map into low and high halves, reusing the original map:
     /// let mut map: BTreeMap<i32, i32> = (0..8).map(|x| (x, x)).collect();
     /// let low: BTreeMap<_, _> = map.extract_if(0..4, |_k, _v| true).collect();
     /// let high = map;

alloc/src/collections/btree/set.rs

@@ -1201,21 +1201,21 @@ impl<T, A: Allocator + Clone> BTreeSet<T, A> {
     /// [`retain`]: BTreeSet::retain
     /// # Examples
     ///
-    /// Splitting a set into even and odd values, reusing the original set:
-    ///
     /// ```
     /// #![feature(btree_extract_if)]
     /// use std::collections::BTreeSet;
     ///
+    /// // Splitting a set into even and odd values, reusing the original set:
     /// let mut set: BTreeSet<i32> = (0..8).collect();
     /// let evens: BTreeSet<_> = set.extract_if(.., |v| v % 2 == 0).collect();
     /// let odds = set;
     /// assert_eq!(evens.into_iter().collect::<Vec<_>>(), vec![0, 2, 4, 6]);
     /// assert_eq!(odds.into_iter().collect::<Vec<_>>(), vec![1, 3, 5, 7]);
     ///
-    /// let mut map: BTreeSet<i32> = (0..8).collect();
-    /// let low: BTreeSet<_> = map.extract_if(0..4, |_v| true).collect();
-    /// let high = map;
+    /// // Splitting a set into low and high halves, reusing the original set:
+    /// let mut set: BTreeSet<i32> = (0..8).collect();
+    /// let low: BTreeSet<_> = set.extract_if(0..4, |_v| true).collect();
+    /// let high = set;
     /// assert_eq!(low.into_iter().collect::<Vec<_>>(), [0, 1, 2, 3]);
     /// assert_eq!(high.into_iter().collect::<Vec<_>>(), [4, 5, 6, 7]);
     /// ```

core/src/convert/num.rs

@@ -175,7 +175,6 @@ impl_from!(u8 => f16, #[stable(feature = "lossless_float_conv", since = "1.6.0")
 impl_from!(u8 => f32, #[stable(feature = "lossless_float_conv", since = "1.6.0")]);
 impl_from!(u8 => f64, #[stable(feature = "lossless_float_conv", since = "1.6.0")]);
 impl_from!(u8 => f128, #[stable(feature = "lossless_float_conv", since = "1.6.0")]);
-impl_from!(u16 => f16, #[stable(feature = "lossless_float_conv", since = "1.6.0")]);
 impl_from!(u16 => f32, #[stable(feature = "lossless_float_conv", since = "1.6.0")]);
 impl_from!(u16 => f64, #[stable(feature = "lossless_float_conv", since = "1.6.0")]);
 impl_from!(u16 => f128, #[stable(feature = "lossless_float_conv", since = "1.6.0")]);

core/src/fmt/mod.rs

@@ -928,6 +928,20 @@ pub use macros::Debug;
 /// [tostring]: ../../std/string/trait.ToString.html
 /// [tostring_function]: ../../std/string/trait.ToString.html#tymethod.to_string
 ///
+/// # Completeness and parseability
+///
+/// `Display` for a type might not necessarily be a lossless or complete representation of the type.
+/// It may omit internal state, precision, or other information the type does not consider important
+/// for user-facing output, as determined by the type. As such, the output of `Display` might not be
+/// possible to parse, and even if it is, the result of parsing might not exactly match the original
+/// value.
+///
+/// However, if a type has a lossless `Display` implementation whose output is meant to be
+/// conveniently machine-parseable and not just meant for human consumption, then the type may wish
+/// to accept the same format in `FromStr`, and document that usage. Having both `Display` and
+/// `FromStr` implementations where the result of `Display` cannot be parsed with `FromStr` may
+/// surprise users.
+///
 /// # Internationalization
 ///
 /// Because a type can only have one `Display` implementation, it is often preferable

core/src/primitive_docs.rs

@@ -1428,6 +1428,18 @@ mod prim_i64 {}
 #[rustc_doc_primitive = "i128"]
 //
 /// The 128-bit signed integer type.
+///
+/// # ABI compatibility
+///
+/// Rust's `i128` is expected to be ABI-compatible with C's `__int128` on platforms where the type
+/// is available, which includes most 64-bit architectures. If any platforms that do not specify
+/// `__int128` are updated to introduce it, the Rust `i128` ABI on relevant targets will be changed
+/// to match.
+///
+/// It is important to note that in C, `__int128` is _not_ the same as `_BitInt(128)`, and the two
+/// types are allowed to have different ABIs. In particular, on x86, `__int128` and `_BitInt(128)`
+/// do not use the same alignment. `i128` is intended to always match `__int128` and does not
+/// attempt to match `_BitInt(128)` on platforms without `__int128`.
 #[stable(feature = "i128", since = "1.26.0")]
 mod prim_i128 {}
 
@@ -1458,6 +1470,8 @@ mod prim_u64 {}
 #[rustc_doc_primitive = "u128"]
 //
 /// The 128-bit unsigned integer type.
+///
+/// Please see [the documentation for `i128`](prim@i128) for information on ABI compatibility.
 #[stable(feature = "i128", since = "1.26.0")]
 mod prim_u128 {}
 

core/src/str/traits.rs

@@ -756,6 +756,20 @@ unsafe impl SliceIndex<str> for ops::RangeToInclusive<usize> {
 /// parse an `i32` with `FromStr`, but not a `&i32`. You can parse a struct that
 /// contains an `i32`, but not one that contains an `&i32`.
 ///
+/// # Input format and round-tripping
+///
+/// The input format expected by a type's `FromStr` implementation depends on the type. Check the
+/// type's documentation for the input formats it knows how to parse. Note that the input format of
+/// a type's `FromStr` implementation might not necessarily accept the output format of its
+/// `Display` implementation, and even if it does, the `Display` implementation may not be lossless
+/// so the round-trip may lose information.
+///
+/// However, if a type has a lossless `Display` implementation whose output is meant to be
+/// conveniently machine-parseable and not just meant for human consumption, then the type may wish
+/// to accept the same format in `FromStr`, and document that usage. Having both `Display` and
+/// `FromStr` implementations where the result of `Display` cannot be parsed with `FromStr` may
+/// surprise users.
+///
 /// # Examples
 ///
 /// Basic implementation of `FromStr` on an example `Point` type:

coretests/tests/lib.rs

@@ -30,6 +30,7 @@
 #![feature(duration_constructors)]
 #![feature(duration_constructors_lite)]
 #![feature(error_generic_member_access)]
+#![feature(exact_div)]
 #![feature(exact_size_is_empty)]
 #![feature(extend_one)]
 #![feature(extern_types)]

coretests/tests/num/int_macros.rs

@@ -683,5 +683,43 @@ macro_rules! int_module {
                 assert_eq_const_safe!($T: <$T>::unbounded_shr(17, SHIFT_AMOUNT_OVERFLOW3), 0);
             }
         }
+
+        const EXACT_DIV_SUCCESS_DIVIDEND1: $T = 42;
+        const EXACT_DIV_SUCCESS_DIVISOR1: $T = 6;
+        const EXACT_DIV_SUCCESS_QUOTIENT1: $T = 7;
+        const EXACT_DIV_SUCCESS_DIVIDEND2: $T = 18;
+        const EXACT_DIV_SUCCESS_DIVISOR2: $T = 3;
+        const EXACT_DIV_SUCCESS_QUOTIENT2: $T = 6;
+        const EXACT_DIV_SUCCESS_DIVIDEND3: $T = -91;
+        const EXACT_DIV_SUCCESS_DIVISOR3: $T = 13;
+        const EXACT_DIV_SUCCESS_QUOTIENT3: $T = -7;
+        const EXACT_DIV_SUCCESS_DIVIDEND4: $T = -57;
+        const EXACT_DIV_SUCCESS_DIVISOR4: $T = -3;
+        const EXACT_DIV_SUCCESS_QUOTIENT4: $T = 19;
+
+        test_runtime_and_compiletime! {
+            fn test_exact_div() {
+                // 42 / 6
+                assert_eq_const_safe!(Option<$T>: <$T>::checked_exact_div(EXACT_DIV_SUCCESS_DIVIDEND1, EXACT_DIV_SUCCESS_DIVISOR1), Some(EXACT_DIV_SUCCESS_QUOTIENT1));
+                assert_eq_const_safe!($T: <$T>::exact_div(EXACT_DIV_SUCCESS_DIVIDEND1, EXACT_DIV_SUCCESS_DIVISOR1), EXACT_DIV_SUCCESS_QUOTIENT1);
+
+                // 18 / 3
+                assert_eq_const_safe!(Option<$T>: <$T>::checked_exact_div(EXACT_DIV_SUCCESS_DIVIDEND2, EXACT_DIV_SUCCESS_DIVISOR2), Some(EXACT_DIV_SUCCESS_QUOTIENT2));
+                assert_eq_const_safe!($T: <$T>::exact_div(EXACT_DIV_SUCCESS_DIVIDEND2, EXACT_DIV_SUCCESS_DIVISOR2), EXACT_DIV_SUCCESS_QUOTIENT2);
+
+                // -91 / 13
+                assert_eq_const_safe!(Option<$T>: <$T>::checked_exact_div(EXACT_DIV_SUCCESS_DIVIDEND3, EXACT_DIV_SUCCESS_DIVISOR3), Some(EXACT_DIV_SUCCESS_QUOTIENT3));
+                assert_eq_const_safe!($T: <$T>::exact_div(EXACT_DIV_SUCCESS_DIVIDEND3, EXACT_DIV_SUCCESS_DIVISOR3), EXACT_DIV_SUCCESS_QUOTIENT3);
+
+                // -57 / -3
+                assert_eq_const_safe!(Option<$T>: <$T>::checked_exact_div(EXACT_DIV_SUCCESS_DIVIDEND4, EXACT_DIV_SUCCESS_DIVISOR4), Some(EXACT_DIV_SUCCESS_QUOTIENT4));
+                assert_eq_const_safe!($T: <$T>::exact_div(EXACT_DIV_SUCCESS_DIVIDEND4, EXACT_DIV_SUCCESS_DIVISOR4), EXACT_DIV_SUCCESS_QUOTIENT4);
+
+                // failures
+                assert_eq_const_safe!(Option<$T>: <$T>::checked_exact_div(1, 2), None);
+                assert_eq_const_safe!(Option<$T>: <$T>::checked_exact_div(<$T>::MIN, -1), None);
+                assert_eq_const_safe!(Option<$T>: <$T>::checked_exact_div(0, 0), None);
+            }
+        }
     };
 }

coretests/tests/num/uint_macros.rs

@@ -516,5 +516,28 @@ macro_rules! uint_module {
                 assert_eq_const_safe!($T: <$T>::unbounded_shr(17, SHIFT_AMOUNT_OVERFLOW3), 0);
             }
         }
+
+        const EXACT_DIV_SUCCESS_DIVIDEND1: $T = 42;
+        const EXACT_DIV_SUCCESS_DIVISOR1: $T = 6;
+        const EXACT_DIV_SUCCESS_QUOTIENT1: $T = 7;
+        const EXACT_DIV_SUCCESS_DIVIDEND2: $T = 18;
+        const EXACT_DIV_SUCCESS_DIVISOR2: $T = 3;
+        const EXACT_DIV_SUCCESS_QUOTIENT2: $T = 6;
+
+        test_runtime_and_compiletime! {
+            fn test_exact_div() {
+                // 42 / 6
+                assert_eq_const_safe!(Option<$T>: <$T>::checked_exact_div(EXACT_DIV_SUCCESS_DIVIDEND1, EXACT_DIV_SUCCESS_DIVISOR1), Some(EXACT_DIV_SUCCESS_QUOTIENT1));
+                assert_eq_const_safe!($T: <$T>::exact_div(EXACT_DIV_SUCCESS_DIVIDEND1, EXACT_DIV_SUCCESS_DIVISOR1), EXACT_DIV_SUCCESS_QUOTIENT1);
+
+                // 18 / 3
+                assert_eq_const_safe!(Option<$T>: <$T>::checked_exact_div(EXACT_DIV_SUCCESS_DIVIDEND2, EXACT_DIV_SUCCESS_DIVISOR2), Some(EXACT_DIV_SUCCESS_QUOTIENT2));
+                assert_eq_const_safe!($T: <$T>::exact_div(EXACT_DIV_SUCCESS_DIVIDEND2, EXACT_DIV_SUCCESS_DIVISOR2), EXACT_DIV_SUCCESS_QUOTIENT2);
+
+                // failures
+                assert_eq_const_safe!(Option<$T>: <$T>::checked_exact_div(1, 2), None);
+                assert_eq_const_safe!(Option<$T>: <$T>::checked_exact_div(0, 0), None);
+            }
+        }
     };
 }

std/src/ffi/os_str.rs

@@ -137,7 +137,8 @@ impl OsString {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[must_use]
     #[inline]
-    pub fn new() -> OsString {
+    #[rustc_const_unstable(feature = "const_pathbuf_osstring_new", issue = "141520")]
+    pub const fn new() -> OsString {
         OsString { inner: Buf::from_string(String::new()) }
     }