Auto merge of #23630 - nrc:coerce-tidy, r=<try>

See notes on the first commit

Closes #18601

r? @nikomatsakis 

cc @eddyb

Author: bors

src/libarena/lib.rs

@@ -429,7 +429,8 @@ impl<T> TypedArenaChunk<T> {
         // Destroy the next chunk.
         let next = self.next;
         let size = calculate_size::<T>(self.capacity);
-        deallocate(self as *mut TypedArenaChunk<T> as *mut u8, size,
+        let self_ptr: *mut TypedArenaChunk<T> = self;
+        deallocate(self_ptr as *mut u8, size,
                    mem::min_align_of::<TypedArenaChunk<T>>());
         if !next.is_null() {
             let capacity = (*next).capacity;

src/libcollections/lib.rs

@@ -23,6 +23,8 @@
        html_root_url = "http://doc.rust-lang.org/nightly/",
        html_playground_url = "http://play.rust-lang.org/")]
 
+#![allow(trivial_casts)]
+#![allow(trivial_numeric_casts)]
 #![feature(alloc)]
 #![feature(box_syntax)]
 #![feature(box_patterns)]

src/libcollections/vec.rs

@@ -1186,8 +1186,8 @@ impl<T: PartialEq> Vec<T> {
 
             // Avoid bounds checks by using unsafe pointers.
             let p = self.as_mut_ptr();
-            let mut r = 1;
-            let mut w = 1;
+            let mut r: usize = 1;
+            let mut w: usize = 1;
 
             while r < ln {
                 let p_r = p.offset(r as isize);

src/libcore/cell.rs

@@ -712,7 +712,11 @@ impl<T> UnsafeCell<T> {
     /// ```
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
-    pub fn get(&self) -> *mut T { &self.value as *const T as *mut T }
+    pub fn get(&self) -> *mut T {
+        // FIXME(#23542) Replace with type ascription.
+        #![allow(trivial_casts)]
+        &self.value as *const T as *mut T
+    }
 
     /// Unwraps the value
     ///

src/libcore/fmt/mod.rs

@@ -829,20 +829,26 @@ impl<T> Pointer for *const T {
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T> Pointer for *mut T {
     fn fmt(&self, f: &mut Formatter) -> Result {
+        // FIXME(#23542) Replace with type ascription.
+        #![allow(trivial_casts)]
         Pointer::fmt(&(*self as *const T), f)
     }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<'a, T> Pointer for &'a T {
     fn fmt(&self, f: &mut Formatter) -> Result {
+        // FIXME(#23542) Replace with type ascription.
+        #![allow(trivial_casts)]
         Pointer::fmt(&(*self as *const T), f)
     }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<'a, T> Pointer for &'a mut T {
     fn fmt(&self, f: &mut Formatter) -> Result {
+        // FIXME(#23542) Replace with type ascription.
+        #![allow(trivial_casts)]
         Pointer::fmt(&(&**self as *const T), f)
     }
 }

src/libcore/fmt/num.rs

@@ -13,6 +13,7 @@
 // FIXME: #6220 Implement floating point formatting
 
 #![allow(unsigned_negation)]
+#![allow(trivial_numeric_casts)]
 
 use fmt;
 use iter::IteratorExt;

src/libcore/hash/mod.rs

@@ -180,6 +180,8 @@ mod impls {
                 }
 
                 fn hash_slice<H: Hasher>(data: &[$ty], state: &mut H) {
+                    // FIXME(#23542) Replace with type ascription.
+                    #![allow(trivial_casts)]
                     let newlen = data.len() * ::$ty::BYTES as usize;
                     let ptr = data.as_ptr() as *const u8;
                     state.write(unsafe { slice::from_raw_parts(ptr, newlen) })

src/libcore/mem.rs

@@ -313,6 +313,8 @@ pub fn drop<T>(_x: T) { }
 #[inline]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub unsafe fn transmute_copy<T, U>(src: &T) -> U {
+    // FIXME(#23542) Replace with type ascription.
+    #![allow(trivial_casts)]
     ptr::read(src as *const T as *const U)
 }
 

src/libcore/num/i16.rs

@@ -12,5 +12,6 @@
 
 #![stable(feature = "rust1", since = "1.0.0")]
 #![doc(primitive = "i16")]
+#![allow(trivial_numeric_casts)]
 
 int_module! { i16, 16 }

src/libcore/num/i32.rs

@@ -12,5 +12,6 @@
 
 #![stable(feature = "rust1", since = "1.0.0")]
 #![doc(primitive = "i32")]
+#![allow(trivial_numeric_casts)]
 
 int_module! { i32, 32 }