Auto merge of #27252 - tbu-:pr_less_transmutes, r=alexcrichton

The replacements are functions that usually use a single `mem::transmute` in their body and restrict input and output via more concrete types than `T` and `U`. Worth noting are the `transmute` functions for slices and the `from_utf8*` family for mutable slices. Additionally, `mem::transmute` was often used for casting raw pointers, when you can already cast raw pointers just fine with `as`.

This builds upon #27233.

1 files changed, 2 insertions, 3 deletions

diff --git a/src/libstd/sync/mpsc/select.rs b/src/libstd/sync/mpsc/select.rs
index 1d31ac165f6..c46e61cf414 100644
--- a/src/libstd/sync/mpsc/select.rs
+++ b/src/libstd/sync/mpsc/select.rs
@@ -62,7 +62,6 @@ use core::prelude::v1::*;
 
 use core::cell::{Cell, UnsafeCell};
 use core::marker;
-use core::mem;
 use core::ptr;
 use core::usize;
 
@@ -281,7 +280,7 @@ impl<'rx, T: Send> Handle<'rx, T> {
     pub unsafe fn add(&mut self) {
         if self.added { return }
         let selector = &mut *self.selector;
-        let me: *mut Handle<'static, ()> = mem::transmute(&*self);
+        let me = self as *mut Handle<'rx, T> as *mut Handle<'static, ()>;
 
         if selector.head.is_null() {
             selector.head = me;
@@ -302,7 +301,7 @@ impl<'rx, T: Send> Handle<'rx, T> {
         if !self.added { return }
 
         let selector = &mut *self.selector;
-        let me: *mut Handle<'static, ()> = mem::transmute(&*self);
+        let me = self as *mut Handle<'rx, T> as *mut Handle<'static, ()>;
 
         if self.prev.is_null() {
             assert_eq!(selector.head, me);