Auto merge of #58254 - kennytm:rollup, r=kennytm

Rollup of 23 pull requests

Successful merges:

 - #58118 (Transition libtest to 2018 edition)
 - #58119 (libproc_macro => 2018)
 - #58123 (Avoid some bounds checks in binary_heap::{PeekMut,Hole})
 - #58124 (libsyntax_pos => 2018)
 - #58133 (libsyntax_ext => 2018)
 - #58136 (Improve error message and docs for non-UTF-8 bytes in stdio on Windows)
 - #58156 (update submodule: rust-installer from 27dec6c to ccdc47b)
 - #58192 (Do not ICE in codegen when using a extern_type static)
 - #58193 (Move librustc to 2018)
 - #58210 (Make an assert debug-only in `find_constraint_paths_between_regions`.)
 - #58217 (librustc_tsan => 2018)
 - #58218 (librustc_msan => 2018)
 - #58219 (librustc_asan => 2018)
 - #58220 (libprofiler_builtins => 2018)
 - #58223 (librustc_lsan => 2018)
 - #58225 (librustc_fs_util => 2018)
 - #58228 (librustc_plugin => 2018)
 - #58236 (librustc_resolve => 2018)
 - #58237 (Fix broken grammar in iter::from_fn() docs)
 - #58239 (librustc_apfloat => 2018)
 - #58240 (librustc_errors => 2018)
 - #58241 (librustc_llvm => 2018)
 - #58242 (Document the one TyKind that isn't documented)

Failed merges:

 - #58185 (Remove images' url to make it work even without internet connection)

r? @ghost

1 files changed, 8 insertions, 3 deletions

diff --git a/src/liballoc/collections/binary_heap.rs b/src/liballoc/collections/binary_heap.rs
index f97522140a8..6214e1ce245 100644
--- a/src/liballoc/collections/binary_heap.rs
+++ b/src/liballoc/collections/binary_heap.rs
@@ -248,14 +248,18 @@ impl<T: Ord> Drop for PeekMut<'_, T> {
 impl<T: Ord> Deref for PeekMut<'_, T> {
     type Target = T;
     fn deref(&self) -> &T {
-        &self.heap.data[0]
+        debug_assert!(!self.heap.is_empty());
+        // SAFE: PeekMut is only instantiated for non-empty heaps
+        unsafe { self.heap.data.get_unchecked(0) }
     }
 }
 
 #[stable(feature = "binary_heap_peek_mut", since = "1.12.0")]
 impl<T: Ord> DerefMut for PeekMut<'_, T> {
     fn deref_mut(&mut self) -> &mut T {
-        &mut self.heap.data[0]
+        debug_assert!(!self.heap.is_empty());
+        // SAFE: PeekMut is only instantiated for non-empty heaps
+        unsafe { self.heap.data.get_unchecked_mut(0) }
     }
 }
 
@@ -865,7 +869,8 @@ impl<'a, T> Hole<'a, T> {
     #[inline]
     unsafe fn new(data: &'a mut [T], pos: usize) -> Self {
         debug_assert!(pos < data.len());
-        let elt = ptr::read(&data[pos]);
+        // SAFE: pos should be inside the slice
+        let elt = ptr::read(data.get_unchecked(pos));
         Hole {
             data,
             elt: ManuallyDrop::new(elt),