Make alignment checks a future incompat lint

Author: oli-obk

src/machine.rs

@@ -24,6 +24,7 @@ use rustc_span::def_id::{CrateNum, DefId};
 use rustc_span::Symbol;
 use rustc_target::abi::Size;
 use rustc_target::spec::abi::Abi;
+use rustc_const_eval::const_eval::CheckAlignment;
 
 use crate::{
     concurrency::{data_race, weak_memory},
@@ -752,8 +753,12 @@ impl<'mir, 'tcx> Machine<'mir, 'tcx> for MiriMachine<'mir, 'tcx> {
     const PANIC_ON_ALLOC_FAIL: bool = false;
 
     #[inline(always)]
-    fn enforce_alignment(ecx: &MiriInterpCx<'mir, 'tcx>) -> bool {
-        ecx.machine.check_alignment != AlignmentCheck::None
+    fn enforce_alignment(ecx: &MiriInterpCx<'mir, 'tcx>) -> CheckAlignment {
+        if ecx.machine.check_alignment == AlignmentCheck::None {
+            CheckAlignment::No
+        } else {
+            CheckAlignment::Error
+        }
     }
 
     #[inline(always)]