Put dynamic check tests into their own file

src/test/ui/consts/const-mut-refs/mut_ref_in_final.rs

@@ -1,6 +1,5 @@
 #![feature(const_mut_refs)]
 #![feature(const_fn)]
-#![feature(const_transmute)]
 #![feature(raw_ref_op)]
 #![feature(const_raw_ptr_deref)]
 
@@ -18,18 +17,8 @@ const B2: Option<&mut i32> = None;
 // Not ok, can't prove that no mutable allocation ends up in final value
 const B3: Option<&mut i32> = Some(&mut 42); //~ ERROR temporary value dropped while borrowed
 
-const fn helper() -> Option<&'static mut i32> { unsafe {
-    // Undefined behaviour, who doesn't love tests like this.
-    // This code never gets executed, because the static checks fail before that.
-    Some(&mut *(42 as *mut i32))
-} }
-// Check that we do not look into function bodies.
-// We treat all functions as not returning a mutable reference, because there is no way to
-// do that without causing the borrow checker to complain (see the B5/helper2 test below).
-const B4: Option<&mut i32> = helper();
-
-const fn helper2(x: &mut i32) -> Option<&mut i32> { Some(x) }
-const B5: Option<&mut i32> = helper2(&mut 42); //~ ERROR temporary value dropped while borrowed
+const fn helper(x: &mut i32) -> Option<&mut i32> { Some(x) }
+const B4: Option<&mut i32> = helper(&mut 42); //~ ERROR temporary value dropped while borrowed
 
 // Ok, because no references to mutable data exist here, since the `{}` moves
 // its value and then takes a reference to that.

src/test/ui/consts/const-mut-refs/mut_ref_in_final.stderr

@@ -1,11 +1,11 @@
 error[E0764]: mutable references are not allowed in the final value of constants
-  --> $DIR/mut_ref_in_final.rs:13:21
+  --> $DIR/mut_ref_in_final.rs:12:21
    |
 LL | const B: *mut i32 = &mut 4;
    |                     ^^^^^^
 
 error[E0716]: temporary value dropped while borrowed
-  --> $DIR/mut_ref_in_final.rs:19:40
+  --> $DIR/mut_ref_in_final.rs:18:40
    |
 LL | const B3: Option<&mut i32> = Some(&mut 42);
    |                              ----------^^-
@@ -15,17 +15,17 @@ LL | const B3: Option<&mut i32> = Some(&mut 42);
    |                              using this value as a constant requires that borrow lasts for `'static`
 
 error[E0716]: temporary value dropped while borrowed
-  --> $DIR/mut_ref_in_final.rs:32:43
+  --> $DIR/mut_ref_in_final.rs:21:42
    |
-LL | const B5: Option<&mut i32> = helper2(&mut 42);
-   |                              -------------^^-
-   |                              |            | |
-   |                              |            | temporary value is freed at the end of this statement
-   |                              |            creates a temporary which is freed while still in use
+LL | const B4: Option<&mut i32> = helper(&mut 42);
+   |                              ------------^^-
+   |                              |           | |
+   |                              |           | temporary value is freed at the end of this statement
+   |                              |           creates a temporary which is freed while still in use
    |                              using this value as a constant requires that borrow lasts for `'static`
 
 error[E0716]: temporary value dropped while borrowed
-  --> $DIR/mut_ref_in_final.rs:47:65
+  --> $DIR/mut_ref_in_final.rs:36:65
    |
 LL | const FOO: NotAMutex<&mut i32> = NotAMutex(UnsafeCell::new(&mut 42));
    |                                  -------------------------------^^--
@@ -35,7 +35,7 @@ LL | const FOO: NotAMutex<&mut i32> = NotAMutex(UnsafeCell::new(&mut 42));
    |                                  using this value as a constant requires that borrow lasts for `'static`
 
 error[E0716]: temporary value dropped while borrowed
-  --> $DIR/mut_ref_in_final.rs:50:67
+  --> $DIR/mut_ref_in_final.rs:39:67
    |
 LL | static FOO2: NotAMutex<&mut i32> = NotAMutex(UnsafeCell::new(&mut 42));
    |                                    -------------------------------^^--
@@ -45,7 +45,7 @@ LL | static FOO2: NotAMutex<&mut i32> = NotAMutex(UnsafeCell::new(&mut 42));
    |                                    using this value as a static requires that borrow lasts for `'static`
 
 error[E0716]: temporary value dropped while borrowed
-  --> $DIR/mut_ref_in_final.rs:53:71
+  --> $DIR/mut_ref_in_final.rs:42:71
    |
 LL | static mut FOO3: NotAMutex<&mut i32> = NotAMutex(UnsafeCell::new(&mut 42));
    |                                        -------------------------------^^--

src/test/ui/consts/const-mut-refs/mut_ref_in_final_dynamic_check.rs

@@ -0,0 +1,28 @@
+#![feature(const_mut_refs)]
+#![feature(const_fn)]
+#![feature(raw_ref_op)]
+#![feature(const_raw_ptr_deref)]
+
+// This file checks that our dynamic checks catch things that the static checks miss.
+// We do not have static checks for these, because we do not look into function bodies.
+// We treat all functions as not returning a mutable reference, because there is no way to
+// do that without causing the borrow checker to complain (see the B4/helper test in
+// mut_ref_in_final.rs).
+
+const fn helper() -> Option<&'static mut i32> { unsafe {
+    // Undefined behaviour (integer as pointer), who doesn't love tests like this.
+    // This code never gets executed, because the static checks fail before that.
+    Some(&mut *(42 as *mut i32)) //~ ERROR any use of this value will cause an error
+} }
+// The error is an evaluation error and not a validation error, so the error is reported
+// directly at the site where it occurs.
+const A: Option<&mut i32> = helper();
+
+const fn helper2() -> Option<&'static mut i32> { unsafe {
+    // Undefined behaviour (dangling pointer), who doesn't love tests like this.
+    // This code never gets executed, because the static checks fail before that.
+    Some(&mut *(&mut 42 as *mut i32))
+} }
+const B: Option<&mut i32> = helper2(); //~ ERROR encountered dangling pointer in final constant
+
+fn main() {}

src/test/ui/consts/const-mut-refs/mut_ref_in_final_dynamic_check.stderr

@@ -0,0 +1,23 @@
+error: any use of this value will cause an error
+  --> $DIR/mut_ref_in_final_dynamic_check.rs:15:10
+   |
+LL |     Some(&mut *(42 as *mut i32))
+   |          ^^^^^^^^^^^^^^^^^^^^^^
+   |          |
+   |          unable to turn bytes into a pointer
+   |          inside `helper` at $DIR/mut_ref_in_final_dynamic_check.rs:15:10
+   |          inside `A` at $DIR/mut_ref_in_final_dynamic_check.rs:19:29
+...
+LL | const A: Option<&mut i32> = helper();
+   | -------------------------------------
+   |
+   = note: `#[deny(const_err)]` on by default
+
+error: encountered dangling pointer in final constant
+  --> $DIR/mut_ref_in_final_dynamic_check.rs:26:1
+   |
+LL | const B: Option<&mut i32> = helper2();
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 2 previous errors
+