Place unions, pointer casts and pointer derefs behind extra feature gates

src/test/compile-fail/cast-ptr-to-int-const.rs

@@ -9,7 +9,7 @@
 // except according to those terms.
 
 fn main() {
-    const X: u32 = main as u32; //~ ERROR E0018
+    const X: u32 = main as u32; //~ ERROR casting pointers to integers in constants is unstable
     const Y: u32 = 0;
-    const Z: u32 = &Y as *const u32 as u32; //~ ERROR E0018
+    const Z: u32 = &Y as *const u32 as u32; //~ ERROR is unstable
 }

src/test/ui/const-deref-ptr.rs

@@ -11,6 +11,7 @@
 // Check that you can't dereference raw pointers in constants.
 
 fn main() {
-    static C: u64 = unsafe {*(0xdeadbeef as *const u64)}; //~ ERROR E0396
+    static C: u64 = unsafe {*(0xdeadbeef as *const u64)};
+    //~^ ERROR dereferencing raw pointers in statics is unstable
     println!("{}", C);
 }

src/test/ui/const-deref-ptr.stderr

@@ -1,9 +1,11 @@
-error[E0396]: raw pointers cannot be dereferenced in statics
+error[E0658]: dereferencing raw pointers in statics is unstable (see issue #51911)
   --> $DIR/const-deref-ptr.rs:14:29
    |
-LL |     static C: u64 = unsafe {*(0xdeadbeef as *const u64)}; //~ ERROR E0396
-   |                             ^^^^^^^^^^^^^^^^^^^^^^^^^^^ dereference of raw pointer in constant
+LL |     static C: u64 = unsafe {*(0xdeadbeef as *const u64)};
+   |                             ^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: add #![feature(const_raw_ptr_deref)] to the crate attributes to enable
 
 error: aborting due to previous error
 
-For more information about this error, try `rustc --explain E0396`.
+For more information about this error, try `rustc --explain E0658`.

src/test/ui/const-eval/const_transmute.rs

@@ -11,6 +11,8 @@
 // compile-pass
 // run-pass
 
+#![feature(const_fn_union)]
+
 union Transmute<T: Copy, U: Copy> {
     t: T,
     u: U,

src/test/ui/const-eval/promoted_const_fn_fail.rs

@@ -10,7 +10,7 @@
 
 // compile-pass
 
-#![feature(const_fn)]
+#![feature(const_fn, const_fn_union)]
 
 #![deny(const_err)]
 

src/test/ui/const-eval/ref_to_float_transmute.rs

@@ -10,6 +10,8 @@
 
 //compile-pass
 
+#![feature(const_fn_union)]
+
 fn main() {}
 
 static FOO: u32 = 42;

src/test/ui/const-eval/ref_to_int_match.rs

@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+#![feature(const_fn_union)]
+
 fn main() {
     let n: Int = 40;
     match n {

src/test/ui/const-eval/ref_to_int_match.stderr

@@ -1,5 +1,5 @@
 error[E0030]: lower range bound must be less than or equal to upper
-  --> $DIR/ref_to_int_match.rs:15:9
+  --> $DIR/ref_to_int_match.rs:17:9
    |
 LL |         10..=BAR => {}, //~ ERROR lower range bound must be less than or equal to upper
    |         ^^ lower bound larger than upper bound

src/test/ui/const-eval/union_promotion.nll.stderr

@@ -0,0 +1,11 @@
+error: internal compiler error: unexpected region for local data ReStatic
+  --> $DIR/union_promotion.rs:19:29
+   |
+LL |       let x: &'static bool = &unsafe { //~ borrowed value does not live long enough
+   |  _____________________________^
+LL | |         Foo { a: &1 }.b == Foo { a: &2 }.b
+LL | |     };
+   | |_____^
+
+error: aborting due to previous error
+

src/test/ui/error-codes/E0396-fixed.rs

@@ -0,0 +1,19 @@
+// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![feature(const_raw_ptr_deref)]
+
+const REG_ADDR: *const u8 = 0x5f3759df as *const u8;
+
+const VALUE: u8 = unsafe { *REG_ADDR };
+//~^ ERROR this constant cannot be used
+
+fn main() {
+}

src/test/ui/error-codes/E0396-fixed.stderr

@@ -0,0 +1,12 @@
+error: this constant cannot be used
+  --> $DIR/E0396-fixed.rs:15:1
+   |
+LL | const VALUE: u8 = unsafe { *REG_ADDR };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^---------^^^
+   |                            |
+   |                            a memory access tried to interpret some bytes as a pointer
+   |
+   = note: #[deny(const_err)] on by default
+
+error: aborting due to previous error
+

src/test/ui/error-codes/E0396.rs

@@ -10,7 +10,8 @@
 
 const REG_ADDR: *const u8 = 0x5f3759df as *const u8;
 
-const VALUE: u8 = unsafe { *REG_ADDR }; //~ ERROR E0396
+const VALUE: u8 = unsafe { *REG_ADDR };
+//~^ ERROR dereferencing raw pointers in constants is unstable
 
 fn main() {
 }

src/test/ui/error-codes/E0396.stderr

@@ -1,9 +1,11 @@
-error[E0396]: raw pointers cannot be dereferenced in constants
+error[E0658]: dereferencing raw pointers in constants is unstable (see issue #51911)
   --> $DIR/E0396.rs:13:28
    |
-LL | const VALUE: u8 = unsafe { *REG_ADDR }; //~ ERROR E0396
-   |                            ^^^^^^^^^ dereference of raw pointer in constant
+LL | const VALUE: u8 = unsafe { *REG_ADDR };
+   |                            ^^^^^^^^^
+   |
+   = help: add #![feature(const_raw_ptr_deref)] to the crate attributes to enable
 
 error: aborting due to previous error
 
-For more information about this error, try `rustc --explain E0396`.
+For more information about this error, try `rustc --explain E0658`.

src/test/ui/issue-17458.rs

@@ -9,7 +9,7 @@
 // except according to those terms.
 
 static X: usize = 0 as *const usize as usize;
-//~^ ERROR: raw pointers cannot be cast to integers in statics
+//~^ ERROR: casting pointers to integers in statics is unstable
 
 fn main() {
     assert_eq!(X, 0);

src/test/ui/issue-18294.rs

@@ -10,6 +10,6 @@
 
 fn main() {
     const X: u32 = 1;
-    const Y: usize = &X as *const u32 as usize; //~ ERROR E0018
+    const Y: usize = &X as *const u32 as usize; //~ ERROR is unstable
     println!("{}", Y);
 }

src/test/ui/union/union-const-eval.rs

@@ -9,6 +9,7 @@
 // except according to those terms.
 
 // compile-pass
+#![feature(const_fn_union)]
 
 union U {
     a: usize,