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

4 files changed, 39 insertions, 5 deletions

diff --git a/src/test/ui/error-codes/E0396-fixed.rs b/src/test/ui/error-codes/E0396-fixed.rs
new file mode 100644
index 00000000000..08d20e7850d
--- /dev/null
+++ b/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() {
+}
diff --git a/src/test/ui/error-codes/E0396-fixed.stderr b/src/test/ui/error-codes/E0396-fixed.stderr
new file mode 100644
index 00000000000..7d3c98c8ea8
--- /dev/null
+++ b/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
+
diff --git a/src/test/ui/error-codes/E0396.rs b/src/test/ui/error-codes/E0396.rs
index 7f34acdfb90..6434620d26a 100644
--- a/src/test/ui/error-codes/E0396.rs
+++ b/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() {
 }
diff --git a/src/test/ui/error-codes/E0396.stderr b/src/test/ui/error-codes/E0396.stderr
index 87dfd50dc97..70331acc0e9 100644
--- a/src/test/ui/error-codes/E0396.stderr
+++ b/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`.