1 files changed, 8 insertions, 2 deletions
diff --git a/src/librustc_mir/interpret/operand.rs b/src/librustc_mir/interpret/operand.rs
index e2fb9de486f..db836d88dd0 100644
--- a/src/librustc_mir/interpret/operand.rs
+++ b/src/librustc_mir/interpret/operand.rs
@@ -240,6 +240,13 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         {
             Some(ptr) => ptr,
             None => {
+                if let Scalar::Ptr(ptr) = mplace.ptr {
+                    // We may be reading from a static.
+                    // In order to ensure that `static FOO: Type = FOO;` causes a cycle error
+                    // instead of magically pulling *any* ZST value from the ether, we need to
+                    // actually access the referenced allocation.
+                    self.memory.get_raw(ptr.alloc_id)?;
+                }
                 return Ok(Some(ImmTy {
                     // zero-sized type
                     imm: Scalar::zst().into(),
@@ -320,8 +327,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
     pub fn read_str(&self, mplace: MPlaceTy<'tcx, M::PointerTag>) -> InterpResult<'tcx, &str> {
         let len = mplace.len(self)?;
         let bytes = self.memory.read_bytes(mplace.ptr, Size::from_bytes(len))?;
-        let str = ::std::str::from_utf8(bytes)
-            .map_err(|err| err_ub_format!("this string is not valid UTF-8: {}", err))?;
+        let str = ::std::str::from_utf8(bytes).map_err(|err| err_ub!(InvalidStr(err)))?;
         Ok(str)
     }