Remove default bound for Machine::MemoryExtra

src/librustc_mir/const_eval.rs

@@ -636,7 +636,8 @@ pub fn const_eval_raw_provider<'tcx>(
         tcx.at(span),
         key.param_env,
         CompileTimeInterpreter::new(),
-        Default::default());
+        Default::default()
+    );
 
     let res = ecx.load_mir(cid.instance.def);
     res.map(|body| {

src/librustc_mir/interpret/machine.rs

@@ -73,7 +73,7 @@ pub trait Machine<'mir, 'tcx>: Sized {
     /// Extra data stored in memory. A reference to this is available when `AllocExtra`
     /// gets initialized, so you can e.g., have an `Rc` here if there is global state you
     /// need access to in the `AllocExtra` hooks.
-    type MemoryExtra: Default;
+    type MemoryExtra;
 
     /// Extra data stored in every allocation.
     type AllocExtra: AllocationExtra<Self::PointerTag> + 'static;