diff --git a/src/test/compile-fail/consts/const-fn-error.rs b/src/test/compile-fail/consts/const-fn-error.rs
index 1a4fc72e8178..5d26059644d1 100644
--- a/src/test/compile-fail/consts/const-fn-error.rs
+++ b/src/test/compile-fail/consts/const-fn-error.rs
@@ -6,7 +6,7 @@ const fn f(x: usize) -> usize {
     let mut sum = 0;
     for i in 0..x {
         //~^ ERROR E0015
-        //~| ERROR E0017
+        //~| ERROR E0658
         //~| ERROR E0080
         //~| ERROR E0744
         //~| ERROR E0019
diff --git a/src/test/ui/check-static-immutable-mut-slices.stderr b/src/test/ui/check-static-immutable-mut-slices.stderr
index 4f4bf16a0ff6..39da824ede57 100644
--- a/src/test/ui/check-static-immutable-mut-slices.stderr
+++ b/src/test/ui/check-static-immutable-mut-slices.stderr
@@ -1,9 +1,12 @@
-error[E0017]: references in statics may only refer to immutable values
+error[E0658]: references in statics may only refer to immutable values
   --> $DIR/check-static-immutable-mut-slices.rs:3:37
    |
 LL | static TEST: &'static mut [isize] = &mut [];
    |                                     ^^^^^^^ statics require immutable values
+   |
+   = note: for more information, see https://github.com/rust-lang/rust/issues/57349
+   = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable
 
 error: aborting due to previous error
 
-For more information about this error, try `rustc --explain E0017`.
+For more information about this error, try `rustc --explain E0658`.
diff --git a/src/test/ui/error-codes/E0017.rs b/src/test/ui/error-codes/E0017.rs
index 3bc518c2c2b7..64be41170d0c 100644
--- a/src/test/ui/error-codes/E0017.rs
+++ b/src/test/ui/error-codes/E0017.rs
@@ -2,10 +2,10 @@ static X: i32 = 1;
 const C: i32 = 2;
 static mut M: i32 = 3;
 
-const CR: &'static mut i32 = &mut C; //~ ERROR E0017
-static STATIC_REF: &'static mut i32 = &mut X; //~ ERROR E0017
+const CR: &'static mut i32 = &mut C; //~ ERROR E0658
+static STATIC_REF: &'static mut i32 = &mut X; //~ ERROR E0658
                                               //~| ERROR E0019
                                               //~| ERROR cannot borrow
-static CONST_REF: &'static mut i32 = &mut C; //~ ERROR E0017
-static STATIC_MUT_REF: &'static mut i32 = unsafe { &mut M }; //~ ERROR E0017
+static CONST_REF: &'static mut i32 = &mut C; //~ ERROR E0658
+static STATIC_MUT_REF: &'static mut i32 = unsafe { &mut M }; //~ ERROR E0658
 fn main() {}
diff --git a/src/test/ui/error-codes/E0017.stderr b/src/test/ui/error-codes/E0017.stderr
index 8c8660adceb7..9a87195a9d05 100644
--- a/src/test/ui/error-codes/E0017.stderr
+++ b/src/test/ui/error-codes/E0017.stderr
@@ -1,8 +1,11 @@
-error[E0017]: references in constants may only refer to immutable values
+error[E0658]: references in constants may only refer to immutable values
   --> $DIR/E0017.rs:5:30
    |
 LL | const CR: &'static mut i32 = &mut C;
    |                              ^^^^^^ constants require immutable values
+   |
+   = note: for more information, see https://github.com/rust-lang/rust/issues/57349
+   = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable
 
 error[E0019]: static contains unimplemented expression type
   --> $DIR/E0017.rs:6:39
@@ -10,11 +13,14 @@ error[E0019]: static contains unimplemented expression type
 LL | static STATIC_REF: &'static mut i32 = &mut X;
    |                                       ^^^^^^
 
-error[E0017]: references in statics may only refer to immutable values
+error[E0658]: references in statics may only refer to immutable values
   --> $DIR/E0017.rs:6:39
    |
 LL | static STATIC_REF: &'static mut i32 = &mut X;
    |                                       ^^^^^^ statics require immutable values
+   |
+   = note: for more information, see https://github.com/rust-lang/rust/issues/57349
+   = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable
 
 error[E0596]: cannot borrow immutable static item `X` as mutable
   --> $DIR/E0017.rs:6:39
@@ -22,19 +28,25 @@ error[E0596]: cannot borrow immutable static item `X` as mutable
 LL | static STATIC_REF: &'static mut i32 = &mut X;
    |                                       ^^^^^^ cannot borrow as mutable
 
-error[E0017]: references in statics may only refer to immutable values
+error[E0658]: references in statics may only refer to immutable values
   --> $DIR/E0017.rs:9:38
    |
 LL | static CONST_REF: &'static mut i32 = &mut C;
    |                                      ^^^^^^ statics require immutable values
+   |
+   = note: for more information, see https://github.com/rust-lang/rust/issues/57349
+   = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable
 
-error[E0017]: references in statics may only refer to immutable values
+error[E0658]: references in statics may only refer to immutable values
   --> $DIR/E0017.rs:10:52
    |
 LL | static STATIC_MUT_REF: &'static mut i32 = unsafe { &mut M };
    |                                                    ^^^^^^ statics require immutable values
+   |
+   = note: for more information, see https://github.com/rust-lang/rust/issues/57349
+   = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable
 
 error: aborting due to 6 previous errors
 
-Some errors have detailed explanations: E0017, E0019, E0596.
-For more information about an error, try `rustc --explain E0017`.
+Some errors have detailed explanations: E0019, E0596, E0658.
+For more information about an error, try `rustc --explain E0019`.
diff --git a/src/test/ui/error-codes/E0388.rs b/src/test/ui/error-codes/E0388.rs
new file mode 100644
index 000000000000..5954e3490b06
--- /dev/null
+++ b/src/test/ui/error-codes/E0388.rs
@@ -0,0 +1,10 @@
+static X: i32 = 1;
+const C: i32 = 2;
+
+const CR: &'static mut i32 = &mut C; //~ ERROR E0658
+static STATIC_REF: &'static mut i32 = &mut X; //~ ERROR E0658
+                                              //~| ERROR cannot borrow
+                                              //~| ERROR E0019
+static CONST_REF: &'static mut i32 = &mut C; //~ ERROR E0658
+
+fn main() {}
diff --git a/src/test/ui/error-codes/E0388.stderr b/src/test/ui/error-codes/E0388.stderr
new file mode 100644
index 000000000000..986307d3f123
--- /dev/null
+++ b/src/test/ui/error-codes/E0388.stderr
@@ -0,0 +1,43 @@
+error[E0658]: references in constants may only refer to immutable values
+  --> $DIR/E0388.rs:4:30
+   |
+LL | const CR: &'static mut i32 = &mut C;
+   |                              ^^^^^^ constants require immutable values
+   |
+   = note: for more information, see https://github.com/rust-lang/rust/issues/57349
+   = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable
+
+error[E0019]: static contains unimplemented expression type
+  --> $DIR/E0388.rs:5:39
+   |
+LL | static STATIC_REF: &'static mut i32 = &mut X;
+   |                                       ^^^^^^
+
+error[E0658]: references in statics may only refer to immutable values
+  --> $DIR/E0388.rs:5:39
+   |
+LL | static STATIC_REF: &'static mut i32 = &mut X;
+   |                                       ^^^^^^ statics require immutable values
+   |
+   = note: for more information, see https://github.com/rust-lang/rust/issues/57349
+   = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable
+
+error[E0596]: cannot borrow immutable static item `X` as mutable
+  --> $DIR/E0388.rs:5:39
+   |
+LL | static STATIC_REF: &'static mut i32 = &mut X;
+   |                                       ^^^^^^ cannot borrow as mutable
+
+error[E0658]: references in statics may only refer to immutable values
+  --> $DIR/E0388.rs:8:38
+   |
+LL | static CONST_REF: &'static mut i32 = &mut C;
+   |                                      ^^^^^^ statics require immutable values
+   |
+   = note: for more information, see https://github.com/rust-lang/rust/issues/57349
+   = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable
+
+error: aborting due to 5 previous errors
+
+Some errors have detailed explanations: E0019, E0596, E0658.
+For more information about an error, try `rustc --explain E0019`.
diff --git a/src/test/ui/issues/issue-17718-const-bad-values.stderr b/src/test/ui/issues/issue-17718-const-bad-values.stderr
index 8d875d37d85f..7e4a62ac9695 100644
--- a/src/test/ui/issues/issue-17718-const-bad-values.stderr
+++ b/src/test/ui/issues/issue-17718-const-bad-values.stderr
@@ -1,8 +1,11 @@
-error[E0017]: references in constants may only refer to immutable values
+error[E0658]: references in constants may only refer to immutable values
   --> $DIR/issue-17718-const-bad-values.rs:1:34
    |
 LL | const C1: &'static mut [usize] = &mut [];
    |                                  ^^^^^^^ constants require immutable values
+   |
+   = note: for more information, see https://github.com/rust-lang/rust/issues/57349
+   = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable
 
 error[E0013]: constants cannot refer to statics, use a constant instead
   --> $DIR/issue-17718-const-bad-values.rs:5:46
@@ -10,13 +13,16 @@ error[E0013]: constants cannot refer to statics, use a constant instead
 LL | const C2: &'static mut usize = unsafe { &mut S };
    |                                              ^
 
-error[E0017]: references in constants may only refer to immutable values
+error[E0658]: references in constants may only refer to immutable values
   --> $DIR/issue-17718-const-bad-values.rs:5:41
    |
 LL | const C2: &'static mut usize = unsafe { &mut S };
    |                                         ^^^^^^ constants require immutable values
+   |
+   = note: for more information, see https://github.com/rust-lang/rust/issues/57349
+   = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable
 
 error: aborting due to 3 previous errors
 
-Some errors have detailed explanations: E0013, E0017.
+Some errors have detailed explanations: E0013, E0658.
 For more information about an error, try `rustc --explain E0013`.
diff --git a/src/test/ui/issues/issue-46604.rs b/src/test/ui/issues/issue-46604.rs
index 4f1ad38dbdd9..e1967eb76554 100644
--- a/src/test/ui/issues/issue-46604.rs
+++ b/src/test/ui/issues/issue-46604.rs
@@ -1,4 +1,4 @@
-static buf: &mut [u8] = &mut [1u8,2,3,4,5,7];   //~ ERROR E0017
+static buf: &mut [u8] = &mut [1u8,2,3,4,5,7];   //~ ERROR E0658
 fn write<T: AsRef<[u8]>>(buffer: T) { }
 
 fn main() {
diff --git a/src/test/ui/issues/issue-46604.stderr b/src/test/ui/issues/issue-46604.stderr
index c72f580f2439..32c7ecbf72e9 100644
--- a/src/test/ui/issues/issue-46604.stderr
+++ b/src/test/ui/issues/issue-46604.stderr
@@ -1,8 +1,11 @@
-error[E0017]: references in statics may only refer to immutable values
+error[E0658]: references in statics may only refer to immutable values
   --> $DIR/issue-46604.rs:1:25
    |
 LL | static buf: &mut [u8] = &mut [1u8,2,3,4,5,7];
    |                         ^^^^^^^^^^^^^^^^^^^^ statics require immutable values
+   |
+   = note: for more information, see https://github.com/rust-lang/rust/issues/57349
+   = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable
 
 error[E0594]: cannot assign to `buf[_]`, as `buf` is an immutable static item
   --> $DIR/issue-46604.rs:6:5
@@ -12,5 +15,5 @@ LL |     buf[0]=2;
 
 error: aborting due to 2 previous errors
 
-Some errors have detailed explanations: E0017, E0594.
-For more information about an error, try `rustc --explain E0017`.
+Some errors have detailed explanations: E0594, E0658.
+For more information about an error, try `rustc --explain E0594`.