From e9c96570d6a0dde7c14c56c1dafe828e69f18c28 Mon Sep 17 00:00:00 2001
From: Ralf Jung <post@ralfj.de>
Date: Thu, 12 Mar 2020 21:22:22 +0100
Subject: [PATCH 1/2] miri engine: fix treatment of abort intrinsic

---
 src/librustc_mir/interpret/intrinsics.rs | 13 +++++--------
 1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/src/librustc_mir/interpret/intrinsics.rs b/src/librustc_mir/interpret/intrinsics.rs
index 869eb1227f23b..37a60bcc8368d 100644
--- a/src/librustc_mir/interpret/intrinsics.rs
+++ b/src/librustc_mir/interpret/intrinsics.rs
@@ -84,14 +84,15 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         let substs = instance.substs;
         let intrinsic_name = self.tcx.item_name(instance.def_id());
 
-        // We currently do not handle any intrinsics that are *allowed* to diverge,
-        // but `transmute` could lack a return place in case of UB.
+        // First handle intrinsics without return place.
         let (dest, ret) = match ret {
-            Some(p) => p,
             None => match intrinsic_name {
-                sym::transmute => throw_ub!(Unreachable),
+                sym::transmute => throw_ub_format!("transmuting to uninhabited type"),
+                sym::abort => M::abort(self)?,
+                // Unsupported diverging intrinsic.
                 _ => return Ok(false),
             },
+            Some(p) => p,
         };
 
         // Keep the patterns in this match ordered the same as the list in
@@ -103,10 +104,6 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                 self.write_scalar(location.ptr, dest)?;
             }
 
-            sym::abort => {
-                M::abort(self)?;
-            }
-
             sym::min_align_of
             | sym::pref_align_of
             | sym::needs_drop

From 13ea774513131b8102f35cb105cc17f39eb1b947 Mon Sep 17 00:00:00 2001
From: Ralf Jung <post@ralfj.de>
Date: Fri, 13 Mar 2020 08:52:04 +0100
Subject: [PATCH 2/2] bless tests

---
 src/test/ui/consts/const-eval/validate_uninhabited_zsts.stderr | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/test/ui/consts/const-eval/validate_uninhabited_zsts.stderr b/src/test/ui/consts/const-eval/validate_uninhabited_zsts.stderr
index d0e35615dab42..cede356a6b8a1 100644
--- a/src/test/ui/consts/const-eval/validate_uninhabited_zsts.stderr
+++ b/src/test/ui/consts/const-eval/validate_uninhabited_zsts.stderr
@@ -4,7 +4,7 @@ warning: any use of this value will cause an error
 LL |     unsafe { std::mem::transmute(()) }
    |              ^^^^^^^^^^^^^^^^^^^^^^^
    |              |
-   |              entering unreachable code
+   |              transmuting to uninhabited type
    |              inside call to `foo` at $DIR/validate_uninhabited_zsts.rs:14:26
 ...
 LL | const FOO: [Empty; 3] = [foo(); 3];