Add dual tests for const_mut_refs

Author: pvdrz

src/test/ui/consts/projection_qualif.mut_refs.stderr

@@ -0,0 +1,12 @@
+error[E0658]: dereferencing raw pointers in constants is unstable
+  --> $DIR/projection_qualif.rs:11:18
+   |
+LL |         unsafe { *b = 5; }
+   |                  ^^^^^^
+   |
+   = note: for more information, see https://github.com/rust-lang/rust/issues/51911
+   = 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 E0658`.

src/test/ui/consts/projection_qualif.rs

@@ -1,11 +1,15 @@
+// revisions: stock mut_refs
+
+#![cfg_attr(mut_refs, feature(const_mut_refs))]
+
 use std::cell::Cell;
 
 const FOO: &u32 = {
     let mut a = 42;
     {
-        let b: *mut u32 = &mut a; //~ ERROR may only refer to immutable values
+        let b: *mut u32 = &mut a; //[stock]~ ERROR may only refer to immutable values
         unsafe { *b = 5; } //~ ERROR dereferencing raw pointers in constants
-        //~^ contains unimplemented expression
+        //[stock]~^ contains unimplemented expression
     }
     &{a}
 };

src/test/ui/consts/projection_qualif.stderr renamed to src/test/ui/consts/projection_qualif.stock.stderr

@@ -1,5 +1,5 @@
 error[E0658]: references in constants may only refer to immutable values
-  --> $DIR/projection_qualif.rs:6:27
+  --> $DIR/projection_qualif.rs:10:27
    |
 LL |         let b: *mut u32 = &mut a;
    |                           ^^^^^^ constants require immutable values
@@ -8,7 +8,7 @@ LL |         let b: *mut u32 = &mut a;
    = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable
 
 error[E0658]: dereferencing raw pointers in constants is unstable
-  --> $DIR/projection_qualif.rs:7:18
+  --> $DIR/projection_qualif.rs:11:18
    |
 LL |         unsafe { *b = 5; }
    |                  ^^^^^^
@@ -17,7 +17,7 @@ LL |         unsafe { *b = 5; }
    = help: add `#![feature(const_raw_ptr_deref)]` to the crate attributes to enable
 
 error[E0019]: constant contains unimplemented expression type
-  --> $DIR/projection_qualif.rs:7:18
+  --> $DIR/projection_qualif.rs:11:18
    |
 LL |         unsafe { *b = 5; }
    |                  ^^^^^^

src/test/ui/consts/static_mut_containing_mut_ref2.mut_refs.stderr

@@ -0,0 +1,9 @@
+error[E0080]: could not evaluate static initializer
+  --> $DIR/static_mut_containing_mut_ref2.rs:7:45
+   |
+LL | pub static mut STDERR_BUFFER: () = unsafe { *(&mut STDERR_BUFFER_SPACE) = 42; };
+   |                                             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ tried to modify a static's initial value from another static's initializer
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0080`.

src/test/ui/consts/static_mut_containing_mut_ref2.rs

@@ -1,7 +1,12 @@
+// revisions: stock mut_refs
+
+#![cfg_attr(mut_refs, feature(const_mut_refs))]
+
 static mut STDERR_BUFFER_SPACE: u8 = 0;
 
 pub static mut STDERR_BUFFER: () = unsafe { *(&mut STDERR_BUFFER_SPACE) = 42; };
-//~^ ERROR references in statics may only refer to immutable values
-//~| ERROR static contains unimplemented expression type
+//[mut_refs]~^ ERROR could not evaluate static initializer
+//[stock]~^^ ERROR references in statics may only refer to immutable values
+//[stock]~| ERROR static contains unimplemented expression type
 
 fn main() {}

src/test/ui/consts/static_mut_containing_mut_ref2.stderr renamed to src/test/ui/consts/static_mut_containing_mut_ref2.stock.stderr

@@ -1,5 +1,5 @@
 error[E0658]: references in statics may only refer to immutable values
-  --> $DIR/static_mut_containing_mut_ref2.rs:3:46
+  --> $DIR/static_mut_containing_mut_ref2.rs:7:46
    |
 LL | pub static mut STDERR_BUFFER: () = unsafe { *(&mut STDERR_BUFFER_SPACE) = 42; };
    |                                              ^^^^^^^^^^^^^^^^^^^^^^^^^^ statics require immutable values
@@ -8,7 +8,7 @@ LL | pub static mut STDERR_BUFFER: () = unsafe { *(&mut STDERR_BUFFER_SPACE) = 4
    = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable
 
 error[E0019]: static contains unimplemented expression type
-  --> $DIR/static_mut_containing_mut_ref2.rs:3:45
+  --> $DIR/static_mut_containing_mut_ref2.rs:7:45
    |
 LL | pub static mut STDERR_BUFFER: () = unsafe { *(&mut STDERR_BUFFER_SPACE) = 42; };
    |                                             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^