Auto merge of #1178 - RalfJung:rustup-visitor, r=RalfJung

adjust for rustc changes

The Miri side of rust-lang/rust#69257

rust-version

@@ -1 +1 @@
-e86c9e6ef8be7ddec0360f20aae7d86c69c59a83
+c839a7b4c26e58319b0c40448dd423facff34cd0

src/helpers.rs

@@ -300,18 +300,15 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
             }
 
             // We have to do *something* for unions.
-            fn visit_union(&mut self, v: MPlaceTy<'tcx, Tag>) -> InterpResult<'tcx> {
+            fn visit_union(&mut self, v: MPlaceTy<'tcx, Tag>, fields: usize) -> InterpResult<'tcx> {
+                assert!(fields > 0); // we should never reach "pseudo-unions" with 0 fields, like primitives
+
                 // With unions, we fall back to whatever the type says, to hopefully be consistent
                 // with LLVM IR.
                 // FIXME: are we consistent, and is this really the behavior we want?
                 let frozen = self.ecx.type_is_freeze(v.layout.ty);
                 if frozen { Ok(()) } else { (self.unsafe_cell_action)(v) }
             }
-
-            // We should never get to a primitive, but always short-circuit somewhere above.
-            fn visit_primitive(&mut self, _v: MPlaceTy<'tcx, Tag>) -> InterpResult<'tcx> {
-                bug!("we should always short-circuit before coming to a primitive")
-            }
         }
     }
 

tests/compile-fail/validity/cast_fn_ptr1.rs

@@ -7,5 +7,5 @@ fn main() {
     let g: fn(*const i32) = unsafe { std::mem::transmute(f as fn(&i32)) };
 
     g(0usize as *const i32)
-    //~^ ERROR encountered 0, but expected something greater or equal to 1
+    //~^ ERROR encountered a NULL reference
 }

tests/compile-fail/validity/cast_fn_ptr2.rs

@@ -7,5 +7,5 @@ fn main() {
     let g: fn() -> &'static i32 = unsafe { std::mem::transmute(f as fn() -> *const i32) };
 
     let _x = g();
-    //~^ ERROR encountered 0, but expected something greater or equal to 1
+    //~^ ERROR encountered a NULL reference
 }

tests/compile-fail/validity/fn_ptr_offset.rs

@@ -6,5 +6,5 @@ fn main() {
     let x : fn() = f;
     let y : *mut u8 = unsafe { mem::transmute(x) };
     let y = y.wrapping_offset(1);
-    let _x : fn() = unsafe { mem::transmute(y) }; //~ ERROR encountered a potentially NULL pointer
+    let _x : fn() = unsafe { mem::transmute(y) }; //~ ERROR encountered a pointer, but expected a function pointer
 }

tests/compile-fail/validity/invalid_bool.rs

@@ -1,3 +1,3 @@
 fn main() {
-    let _b = unsafe { std::mem::transmute::<u8, bool>(2) }; //~ ERROR encountered 2, but expected something less or equal to 1
+    let _b = unsafe { std::mem::transmute::<u8, bool>(2) }; //~ ERROR encountered 2, but expected a boolean
 }

tests/compile-fail/validity/invalid_char.rs

@@ -1,6 +1,6 @@
 fn main() {
     assert!(std::char::from_u32(-1_i32 as u32).is_none());
-    let _val = match unsafe { std::mem::transmute::<i32, char>(-1) } { //~ ERROR encountered 4294967295, but expected something less or equal to 1114111
+    let _val = match unsafe { std::mem::transmute::<i32, char>(-1) } { //~ ERROR encountered 4294967295, but expected a valid unicode codepoint
         'a' => {true},
         'b' => {false},
         _ => {true},