Auto merge of rust-lang#77201 - matthewjasper:rename-get-unchecked, r…

…=spastorino

Rename Iterator::get_unchecked

Closes rust-lang#76479

r? `@pnkfelix`

library/alloc/src/vec.rs

@@ -2980,12 +2980,18 @@ impl<T> Iterator for IntoIter<T> {
         self.len()
     }
 
-    unsafe fn get_unchecked(&mut self, i: usize) -> Self::Item
+    unsafe fn __iterator_get_unchecked(&mut self, i: usize) -> Self::Item
     where
         Self: TrustedRandomAccess,
     {
-        // SAFETY: the caller must uphold the contract for
-        // `Iterator::get_unchecked`.
+        // SAFETY: the caller must guarantee that `i` is in bounds of the
+        // `Vec<T>`, so `i` cannot overflow an `isize`, and the `self.ptr.add(i)`
+        // is guaranteed to pointer to an element of the `Vec<T>` and
+        // thus guaranteed to be valid to dereference.
+        //
+        // Also note the implementation of `Self: TrustedRandomAccess` requires
+        // that `T: Copy` so reading elements from the buffer doesn't invalidate
+        // them for `Drop`.
         unsafe {
             if mem::size_of::<T>() == 0 { mem::zeroed() } else { ptr::read(self.ptr.add(i)) }
         }

library/core/src/iter/adapters/fuse.rs

@@ -115,12 +115,13 @@ where
     }
 
     #[inline]
-    unsafe fn get_unchecked(&mut self, idx: usize) -> Self::Item
+    unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> Self::Item
     where
         Self: TrustedRandomAccess,
     {
         match self.iter {
-            // SAFETY: the caller must uphold the contract for `Iterator::get_unchecked`.
+            // SAFETY: the caller must uphold the contract for
+            // `Iterator::__iterator_get_unchecked`.
             Some(ref mut iter) => unsafe { try_get_unchecked(iter, idx) },
             // SAFETY: the caller asserts there is an item at `i`, so we're not exhausted.
             None => unsafe { intrinsics::unreachable() },

library/core/src/iter/adapters/mod.rs

@@ -285,12 +285,12 @@ where
         self.it.count()
     }
 
-    unsafe fn get_unchecked(&mut self, idx: usize) -> T
+    unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> T
     where
         Self: TrustedRandomAccess,
     {
         // SAFETY: the caller must uphold the contract for
-        // `Iterator::get_unchecked`.
+        // `Iterator::__iterator_get_unchecked`.
         *unsafe { try_get_unchecked(&mut self.it, idx) }
     }
 }
@@ -420,12 +420,12 @@ where
         self.it.map(T::clone).fold(init, f)
     }
 
-    unsafe fn get_unchecked(&mut self, idx: usize) -> T
+    unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> T
     where
         Self: TrustedRandomAccess,
     {
         // SAFETY: the caller must uphold the contract for
-        // `Iterator::get_unchecked`.
+        // `Iterator::__iterator_get_unchecked`.
         unsafe { try_get_unchecked(&mut self.it, idx).clone() }
     }
 }
@@ -935,12 +935,12 @@ where
         self.iter.fold(init, map_fold(self.f, g))
     }
 
-    unsafe fn get_unchecked(&mut self, idx: usize) -> B
+    unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> B
     where
         Self: TrustedRandomAccess,
     {
         // SAFETY: the caller must uphold the contract for
-        // `Iterator::get_unchecked`.
+        // `Iterator::__iterator_get_unchecked`.
         unsafe { (self.f)(try_get_unchecked(&mut self.iter, idx)) }
     }
 }
@@ -1431,12 +1431,12 @@ where
         self.iter.fold(init, enumerate(self.count, fold))
     }
 
-    unsafe fn get_unchecked(&mut self, idx: usize) -> <Self as Iterator>::Item
+    unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> <Self as Iterator>::Item
     where
         Self: TrustedRandomAccess,
     {
         // SAFETY: the caller must uphold the contract for
-        // `Iterator::get_unchecked`.
+        // `Iterator::__iterator_get_unchecked`.
         let value = unsafe { try_get_unchecked(&mut self.iter, idx) };
         (Add::add(self.count, idx), value)
     }

library/core/src/iter/adapters/zip.rs

@@ -59,12 +59,12 @@ where
     }
 
     #[inline]
-    unsafe fn get_unchecked(&mut self, idx: usize) -> Self::Item
+    unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> Self::Item
     where
         Self: TrustedRandomAccess,
     {
-        // SAFETY: `ZipImpl::get_unchecked` has same safety requirements as
-        // `Iterator::get_unchecked`.
+        // SAFETY: `ZipImpl::__iterator_get_unchecked` has same safety
+        // requirements as `Iterator::__iterator_get_unchecked`.
         unsafe { ZipImpl::get_unchecked(self, idx) }
     }
 }
@@ -93,7 +93,7 @@ trait ZipImpl<A, B> {
     where
         A: DoubleEndedIterator + ExactSizeIterator,
         B: DoubleEndedIterator + ExactSizeIterator;
-    // This has the same safety requirements as `Iterator::get_unchecked`
+    // This has the same safety requirements as `Iterator::__iterator_get_unchecked`
     unsafe fn get_unchecked(&mut self, idx: usize) -> <Self as Iterator>::Item
     where
         Self: Iterator + TrustedRandomAccess;
@@ -197,12 +197,14 @@ where
             let i = self.index;
             self.index += 1;
             // SAFETY: `i` is smaller than `self.len`, thus smaller than `self.a.len()` and `self.b.len()`
-            unsafe { Some((self.a.get_unchecked(i), self.b.get_unchecked(i))) }
+            unsafe {
+                Some((self.a.__iterator_get_unchecked(i), self.b.__iterator_get_unchecked(i)))
+            }
         } else if A::may_have_side_effect() && self.index < self.a.size() {
             // match the base implementation's potential side effects
             // SAFETY: we just checked that `self.index` < `self.a.len()`
             unsafe {
-                self.a.get_unchecked(self.index);
+                self.a.__iterator_get_unchecked(self.index);
             }
             self.index += 1;
             None
@@ -229,13 +231,13 @@ where
                 // ensures that `end` is smaller than or equal to `self.len`,
                 // so `i` is also smaller than `self.len`.
                 unsafe {
-                    self.a.get_unchecked(i);
+                    self.a.__iterator_get_unchecked(i);
                 }
             }
             if B::may_have_side_effect() {
                 // SAFETY: same as above.
                 unsafe {
-                    self.b.get_unchecked(i);
+                    self.b.__iterator_get_unchecked(i);
                 }
             }
         }
@@ -277,7 +279,9 @@ where
             let i = self.len;
             // SAFETY: `i` is smaller than the previous value of `self.len`,
             // which is also smaller than or equal to `self.a.len()` and `self.b.len()`
-            unsafe { Some((self.a.get_unchecked(i), self.b.get_unchecked(i))) }
+            unsafe {
+                Some((self.a.__iterator_get_unchecked(i), self.b.__iterator_get_unchecked(i)))
+            }
         } else {
             None
         }
@@ -286,8 +290,8 @@ where
     #[inline]
     unsafe fn get_unchecked(&mut self, idx: usize) -> <Self as Iterator>::Item {
         // SAFETY: the caller must uphold the contract for
-        // `Iterator::get_unchecked`.
-        unsafe { (self.a.get_unchecked(idx), self.b.get_unchecked(idx)) }
+        // `Iterator::__iterator_get_unchecked`.
+        unsafe { (self.a.__iterator_get_unchecked(idx), self.b.__iterator_get_unchecked(idx)) }
     }
 }
 
@@ -386,8 +390,8 @@ impl<A: Debug + TrustedRandomAccess, B: Debug + TrustedRandomAccess> ZipFmt<A, B
 ///
 /// `size` may not be overridden.
 ///
-/// `<Self as Iterator>::get_unchecked` must be safe to call provided the
-/// following conditions are met.
+/// `<Self as Iterator>::__iterator_get_unchecked` must be safe to call
+/// provided the following conditions are met.
 ///
 /// 1. `0 <= idx` and `idx < self.size()`.
 /// 2. If `self: !Clone`, then `get_unchecked` is never called with the same
@@ -399,7 +403,7 @@ impl<A: Debug + TrustedRandomAccess, B: Debug + TrustedRandomAccess> ZipFmt<A, B
 ///     * `std::clone::Clone::clone`
 ///     * `std::iter::Iterator::size_hint()`
 ///     * `std::iter::Iterator::next_back()`
-///     * `std::iter::Iterator::get_unchecked()`
+///     * `std::iter::Iterator::__iterator_get_unchecked()`
 ///     * `std::iter::TrustedRandomAccess::size()`
 ///
 /// Further, given that these conditions are met, it must guarantee that:
@@ -424,7 +428,7 @@ pub unsafe trait TrustedRandomAccess: Sized {
     fn may_have_side_effect() -> bool;
 }
 
-/// Like `Iterator::get_unchecked`, but doesn't require the compiler to
+/// Like `Iterator::__iterator_get_unchecked`, but doesn't require the compiler to
 /// know that `U: TrustedRandomAccess`.
 ///
 /// ## Safety
@@ -436,13 +440,13 @@ where
     I: Iterator,
 {
     // SAFETY: the caller must uphold the contract for
-    // `Iterator::get_unchecked`.
+    // `Iterator::__iterator_get_unchecked`.
     unsafe { it.try_get_unchecked(idx) }
 }
 
 unsafe trait SpecTrustedRandomAccess: Iterator {
     /// If `Self: TrustedRandomAccess`, it must be safe to call a
-    /// `Iterator::get_unchecked(self, index)`.
+    /// `Iterator::__iterator_get_unchecked(self, index)`.
     unsafe fn try_get_unchecked(&mut self, index: usize) -> Self::Item;
 }
 
@@ -455,7 +459,7 @@ unsafe impl<I: Iterator> SpecTrustedRandomAccess for I {
 unsafe impl<I: Iterator + TrustedRandomAccess> SpecTrustedRandomAccess for I {
     unsafe fn try_get_unchecked(&mut self, index: usize) -> Self::Item {
         // SAFETY: the caller must uphold the contract for
-        // `Iterator::get_unchecked`.
-        unsafe { self.get_unchecked(index) }
+        // `Iterator::__iterator_get_unchecked`.
+        unsafe { self.__iterator_get_unchecked(index) }
     }
 }

library/core/src/iter/traits/iterator.rs

@@ -3241,10 +3241,12 @@ pub trait Iterator {
     }
 
     /// See [TrustedRandomAccess]
+    // The unusual name is to avoid name collisions in method resolution
+    // see #76479.
     #[inline]
     #[doc(hidden)]
     #[unstable(feature = "trusted_random_access", issue = "none")]
-    unsafe fn get_unchecked(&mut self, _idx: usize) -> Self::Item
+    unsafe fn __iterator_get_unchecked(&mut self, _idx: usize) -> Self::Item
     where
         Self: TrustedRandomAccess,
     {

library/core/src/slice/iter.rs

@@ -1178,7 +1178,7 @@ impl<'a, T> Iterator for Windows<'a, T> {
     }
 
     #[doc(hidden)]
-    unsafe fn get_unchecked(&mut self, idx: usize) -> Self::Item {
+    unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> Self::Item {
         // SAFETY: since the caller guarantees that `i` is in bounds,
         // which means that `i` cannot overflow an `isize`, and the
         // slice created by `from_raw_parts` is a subslice of `self.v`
@@ -1324,7 +1324,7 @@ impl<'a, T> Iterator for Chunks<'a, T> {
     }
 
     #[doc(hidden)]
-    unsafe fn get_unchecked(&mut self, idx: usize) -> Self::Item {
+    unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> Self::Item {
         let start = idx * self.chunk_size;
         let end = match start.checked_add(self.chunk_size) {
             None => self.v.len(),
@@ -1480,13 +1480,13 @@ impl<'a, T> Iterator for ChunksMut<'a, T> {
     }
 
     #[doc(hidden)]
-    unsafe fn get_unchecked(&mut self, idx: usize) -> Self::Item {
+    unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> Self::Item {
         let start = idx * self.chunk_size;
         let end = match start.checked_add(self.chunk_size) {
             None => self.v.len(),
             Some(end) => cmp::min(end, self.v.len()),
         };
-        // SAFETY: see comments for `Chunks::get_unchecked`.
+        // SAFETY: see comments for `Chunks::__iterator_get_unchecked`.
         //
         // Also note that the caller also guarantees that we're never called
         // with the same index again, and that no other methods that will
@@ -1642,9 +1642,9 @@ impl<'a, T> Iterator for ChunksExact<'a, T> {
     }
 
     #[doc(hidden)]
-    unsafe fn get_unchecked(&mut self, idx: usize) -> Self::Item {
+    unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> Self::Item {
         let start = idx * self.chunk_size;
-        // SAFETY: mostly identical to `Chunks::get_unchecked`.
+        // SAFETY: mostly identical to `Chunks::__iterator_get_unchecked`.
         unsafe { from_raw_parts(self.v.as_ptr().add(start), self.chunk_size) }
     }
 }
@@ -1785,9 +1785,9 @@ impl<'a, T> Iterator for ChunksExactMut<'a, T> {
     }
 
     #[doc(hidden)]
-    unsafe fn get_unchecked(&mut self, idx: usize) -> Self::Item {
+    unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> Self::Item {
         let start = idx * self.chunk_size;
-        // SAFETY: see comments for `ChunksMut::get_unchecked`.
+        // SAFETY: see comments for `ChunksMut::__iterator_get_unchecked`.
         unsafe { from_raw_parts_mut(self.v.as_mut_ptr().add(start), self.chunk_size) }
     }
 }
@@ -2030,10 +2030,10 @@ impl<'a, T, const N: usize> Iterator for ArrayChunks<'a, T, N> {
         self.iter.last()
     }
 
-    unsafe fn get_unchecked(&mut self, i: usize) -> &'a [T; N] {
-        // SAFETY: The safety guarantees of `get_unchecked` are transferred to
-        // the caller.
-        unsafe { self.iter.get_unchecked(i) }
+    unsafe fn __iterator_get_unchecked(&mut self, i: usize) -> &'a [T; N] {
+        // SAFETY: The safety guarantees of `__iterator_get_unchecked` are
+        // transferred to the caller.
+        unsafe { self.iter.__iterator_get_unchecked(i) }
     }
 }
 
@@ -2141,10 +2141,10 @@ impl<'a, T, const N: usize> Iterator for ArrayChunksMut<'a, T, N> {
         self.iter.last()
     }
 
-    unsafe fn get_unchecked(&mut self, i: usize) -> &'a mut [T; N] {
-        // SAFETY: The safety guarantees of `get_unchecked` are transferred to
+    unsafe fn __iterator_get_unchecked(&mut self, i: usize) -> &'a mut [T; N] {
+        // SAFETY: The safety guarantees of `__iterator_get_unchecked` are transferred to
         // the caller.
-        unsafe { self.iter.get_unchecked(i) }
+        unsafe { self.iter.__iterator_get_unchecked(i) }
     }
 }
 
@@ -2278,13 +2278,13 @@ impl<'a, T> Iterator for RChunks<'a, T> {
     }
 
     #[doc(hidden)]
-    unsafe fn get_unchecked(&mut self, idx: usize) -> Self::Item {
+    unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> Self::Item {
         let end = self.v.len() - idx * self.chunk_size;
         let start = match end.checked_sub(self.chunk_size) {
             None => 0,
             Some(start) => start,
         };
-        // SAFETY: mostly identical to `Chunks::get_unchecked`.
+        // SAFETY: mostly identical to `Chunks::__iterator_get_unchecked`.
         unsafe { from_raw_parts(self.v.as_ptr().add(start), end - start) }
     }
 }
@@ -2431,13 +2431,14 @@ impl<'a, T> Iterator for RChunksMut<'a, T> {
     }
 
     #[doc(hidden)]
-    unsafe fn get_unchecked(&mut self, idx: usize) -> Self::Item {
+    unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> Self::Item {
         let end = self.v.len() - idx * self.chunk_size;
         let start = match end.checked_sub(self.chunk_size) {
             None => 0,
             Some(start) => start,
         };
-        // SAFETY: see comments for `RChunks::get_unchecked` and `ChunksMut::get_unchecked`
+        // SAFETY: see comments for `RChunks::__iterator_get_unchecked` and
+        // `ChunksMut::__iterator_get_unchecked`
         unsafe { from_raw_parts_mut(self.v.as_mut_ptr().add(start), end - start) }
     }
 }
@@ -2585,11 +2586,11 @@ impl<'a, T> Iterator for RChunksExact<'a, T> {
     }
 
     #[doc(hidden)]
-    unsafe fn get_unchecked(&mut self, idx: usize) -> Self::Item {
+    unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> Self::Item {
         let end = self.v.len() - idx * self.chunk_size;
         let start = end - self.chunk_size;
         // SAFETY:
-        // SAFETY: mostmy identical to `Chunks::get_unchecked`.
+        // SAFETY: mostmy identical to `Chunks::__iterator_get_unchecked`.
         unsafe { from_raw_parts(self.v.as_ptr().add(start), self.chunk_size) }
     }
 }
@@ -2734,10 +2735,10 @@ impl<'a, T> Iterator for RChunksExactMut<'a, T> {
     }
 
     #[doc(hidden)]
-    unsafe fn get_unchecked(&mut self, idx: usize) -> Self::Item {
+    unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> Self::Item {
         let end = self.v.len() - idx * self.chunk_size;
         let start = end - self.chunk_size;
-        // SAFETY: see comments for `RChunksMut::get_unchecked`.
+        // SAFETY: see comments for `RChunksMut::__iterator_get_unchecked`.
         unsafe { from_raw_parts_mut(self.v.as_mut_ptr().add(start), self.chunk_size) }
     }
 }