rename MPlaceTy::dangling to fake_alloc_zst

Author: RalfJung

compiler/rustc_const_eval/src/interpret/place.rs

@@ -188,8 +188,10 @@ impl<Tag: Provenance> Place<Tag> {
 
 impl<'tcx, Tag: Provenance> MPlaceTy<'tcx, Tag> {
     /// Produces a MemPlace that works for ZST but nothing else.
+    /// Conceptually this is a new allocation, but it doesn't actually create an allocation so you
+    /// don't need to worry about memory leaks.
     #[inline]
-    pub fn dangling(layout: TyAndLayout<'tcx>) -> Self {
+    pub fn fake_alloc_zst(layout: TyAndLayout<'tcx>) -> Self {
         assert!(layout.is_zst());
         let align = layout.align.abi;
         let ptr = Pointer::from_addr(align.bytes()); // no provenance, absolute address

compiler/rustc_const_eval/src/interpret/terminator.rs

@@ -617,7 +617,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             place.to_ref(self),
             self.layout_of(self.tcx.mk_mut_ptr(place.layout.ty))?,
         );
-        let ret = MPlaceTy::dangling(self.layout_of(self.tcx.types.unit)?);
+        let ret = MPlaceTy::fake_alloc_zst(self.layout_of(self.tcx.types.unit)?);
 
         self.eval_fn_call(
             FnVal::Instance(instance),