Auto merge of rust-lang#130631 - GuillaumeGomez:rollup-jpgy1iv, r=Gui…

…llaumeGomez

Rollup of 7 pull requests

Successful merges:

 - rust-lang#128209 (Remove macOS 10.10 dynamic linker bug workaround)
 - rust-lang#130526 (Begin experimental support for pin reborrowing)
 - rust-lang#130611 (Address diagnostics regression for `const_char_encode_utf8`.)
 - rust-lang#130614 (Add arm64e-apple-tvos target)
 - rust-lang#130617 (bail if there are too many non-region infer vars in the query response)
 - rust-lang#130619 (Fix scraped examples height)
 - rust-lang#130624 (Add `Vec::as_non_null`)

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

alloc/src/vec/mod.rs

@@ -1584,7 +1584,8 @@ impl<T, A: Allocator> Vec<T, A> {
     ///
     /// This method guarantees that for the purpose of the aliasing model, this method
     /// does not materialize a reference to the underlying slice, and thus the returned pointer
-    /// will remain valid when mixed with other calls to [`as_ptr`] and [`as_mut_ptr`].
+    /// will remain valid when mixed with other calls to [`as_ptr`], [`as_mut_ptr`],
+    /// and [`as_non_null`].
     /// Note that calling other methods that materialize mutable references to the slice,
     /// or mutable references to specific elements you are planning on accessing through this pointer,
     /// as well as writing to those elements, may still invalidate this pointer.
@@ -1621,6 +1622,7 @@ impl<T, A: Allocator> Vec<T, A> {
     ///
     /// [`as_mut_ptr`]: Vec::as_mut_ptr
     /// [`as_ptr`]: Vec::as_ptr
+    /// [`as_non_null`]: Vec::as_non_null
     #[stable(feature = "vec_as_ptr", since = "1.37.0")]
     #[rustc_never_returns_null_ptr]
     #[inline]
@@ -1640,7 +1642,8 @@ impl<T, A: Allocator> Vec<T, A> {
     ///
     /// This method guarantees that for the purpose of the aliasing model, this method
     /// does not materialize a reference to the underlying slice, and thus the returned pointer
-    /// will remain valid when mixed with other calls to [`as_ptr`] and [`as_mut_ptr`].
+    /// will remain valid when mixed with other calls to [`as_ptr`], [`as_mut_ptr`],
+    /// and [`as_non_null`].
     /// Note that calling other methods that materialize references to the slice,
     /// or references to specific elements you are planning on accessing through this pointer,
     /// may still invalidate this pointer.
@@ -1680,6 +1683,7 @@ impl<T, A: Allocator> Vec<T, A> {
     ///
     /// [`as_mut_ptr`]: Vec::as_mut_ptr
     /// [`as_ptr`]: Vec::as_ptr
+    /// [`as_non_null`]: Vec::as_non_null
     #[stable(feature = "vec_as_ptr", since = "1.37.0")]
     #[rustc_never_returns_null_ptr]
     #[inline]
@@ -1689,6 +1693,69 @@ impl<T, A: Allocator> Vec<T, A> {
         self.buf.ptr()
     }
 
+    /// Returns a `NonNull` pointer to the vector's buffer, or a dangling
+    /// `NonNull` pointer valid for zero sized reads if the vector didn't allocate.
+    ///
+    /// The caller must ensure that the vector outlives the pointer this
+    /// function returns, or else it will end up dangling.
+    /// Modifying the vector may cause its buffer to be reallocated,
+    /// which would also make any pointers to it invalid.
+    ///
+    /// This method guarantees that for the purpose of the aliasing model, this method
+    /// does not materialize a reference to the underlying slice, and thus the returned pointer
+    /// will remain valid when mixed with other calls to [`as_ptr`], [`as_mut_ptr`],
+    /// and [`as_non_null`].
+    /// Note that calling other methods that materialize references to the slice,
+    /// or references to specific elements you are planning on accessing through this pointer,
+    /// may still invalidate this pointer.
+    /// See the second example below for how this guarantee can be used.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(box_vec_non_null)]
+    ///
+    /// // Allocate vector big enough for 4 elements.
+    /// let size = 4;
+    /// let mut x: Vec<i32> = Vec::with_capacity(size);
+    /// let x_ptr = x.as_non_null();
+    ///
+    /// // Initialize elements via raw pointer writes, then set length.
+    /// unsafe {
+    ///     for i in 0..size {
+    ///         x_ptr.add(i).write(i as i32);
+    ///     }
+    ///     x.set_len(size);
+    /// }
+    /// assert_eq!(&*x, &[0, 1, 2, 3]);
+    /// ```
+    ///
+    /// Due to the aliasing guarantee, the following code is legal:
+    ///
+    /// ```rust
+    /// #![feature(box_vec_non_null)]
+    ///
+    /// unsafe {
+    ///     let mut v = vec![0];
+    ///     let ptr1 = v.as_non_null();
+    ///     ptr1.write(1);
+    ///     let ptr2 = v.as_non_null();
+    ///     ptr2.write(2);
+    ///     // Notably, the write to `ptr2` did *not* invalidate `ptr1`:
+    ///     ptr1.write(3);
+    /// }
+    /// ```
+    ///
+    /// [`as_mut_ptr`]: Vec::as_mut_ptr
+    /// [`as_ptr`]: Vec::as_ptr
+    /// [`as_non_null`]: Vec::as_non_null
+    #[unstable(feature = "box_vec_non_null", reason = "new API", issue = "130364")]
+    #[inline]
+    pub fn as_non_null(&mut self) -> NonNull<T> {
+        // SAFETY: A `Vec` always has a non-null pointer.
+        unsafe { NonNull::new_unchecked(self.as_mut_ptr()) }
+    }
+
     /// Returns a reference to the underlying allocator.
     #[unstable(feature = "allocator_api", issue = "32838")]
     #[inline]

core/src/char/methods.rs

@@ -1,6 +1,7 @@
 //! impl char {}
 
 use super::*;
+use crate::intrinsics::const_eval_select;
 use crate::slice;
 use crate::str::from_utf8_unchecked_mut;
 use crate::unicode::printable::is_printable;
@@ -1762,6 +1763,15 @@ const fn len_utf8(code: u32) -> usize {
 #[doc(hidden)]
 #[inline]
 pub const fn encode_utf8_raw(code: u32, dst: &mut [u8]) -> &mut [u8] {
+    const fn panic_at_const(_code: u32, _len: usize, _dst_len: usize) {
+        // Note that we cannot format in constant expressions.
+        panic!("encode_utf8: buffer does not have enough bytes to encode code point");
+    }
+    fn panic_at_rt(code: u32, len: usize, dst_len: usize) {
+        panic!(
+            "encode_utf8: need {len} bytes to encode U+{code:04X} but buffer has just {dst_len}",
+        );
+    }
     let len = len_utf8(code);
     match (len, &mut *dst) {
         (1, [a, ..]) => {
@@ -1782,8 +1792,8 @@ pub const fn encode_utf8_raw(code: u32, dst: &mut [u8]) -> &mut [u8] {
             *c = (code >> 6 & 0x3F) as u8 | TAG_CONT;
             *d = (code & 0x3F) as u8 | TAG_CONT;
         }
-        // Note that we cannot format in constant expressions.
-        _ => panic!("encode_utf8: buffer does not have enough bytes to encode code point"),
+        // FIXME(const-hack): We would prefer to have streamlined panics when formatters become const-friendly.
+        _ => const_eval_select((code, len, dst.len()), panic_at_const, panic_at_rt),
     };
     // SAFETY: `<&mut [u8]>::as_mut_ptr` is guaranteed to return a valid pointer and `len` has been tested to be within bounds.
     unsafe { slice::from_raw_parts_mut(dst.as_mut_ptr(), len) }

std/src/fs.rs

@@ -2473,16 +2473,15 @@ pub fn remove_dir<P: AsRef<Path>>(path: P) -> io::Result<()> {
 /// # Platform-specific behavior
 ///
 /// This function currently corresponds to `openat`, `fdopendir`, `unlinkat` and `lstat` functions
-/// on Unix (except for macOS before version 10.10 and REDOX) and the `CreateFileW`,
-/// `GetFileInformationByHandleEx`, `SetFileInformationByHandle`, and `NtCreateFile` functions on
-/// Windows. Note that, this [may change in the future][changes].
+/// on Unix (except for REDOX) and the `CreateFileW`, `GetFileInformationByHandleEx`,
+/// `SetFileInformationByHandle`, and `NtCreateFile` functions on Windows. Note that, this
+/// [may change in the future][changes].
 ///
 /// [changes]: io#platform-specific-behavior
 ///
-/// On macOS before version 10.10 and REDOX, as well as when running in Miri for any target, this
-/// function is not protected against time-of-check to time-of-use (TOCTOU) race conditions, and
-/// should not be used in security-sensitive code on those platforms. All other platforms are
-/// protected.
+/// On REDOX, as well as when running in Miri for any target, this function is not protected against
+/// time-of-check to time-of-use (TOCTOU) race conditions, and should not be used in
+/// security-sensitive code on those platforms. All other platforms are protected.
 ///
 /// # Errors
 ///