InterpCx.read_size_and_align_from_vtable to InterpCx.read_mem_pos_from_vtable

Author: Dante-Broggi

src/librustc_mir/interpret/eval_context.rs

@@ -448,8 +448,8 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             ty::Dynamic(..) => {
                 let vtable = metadata.expect("dyn trait fat ptr must have vtable");
                 // Read size and align from vtable (already checks size).
-                let (size, align) = self.read_size_and_align_from_vtable(vtable)?;
-                let mem_pos = MemoryPosition::new(size, align);
+                let mem_pos = self.read_mem_pos_from_vtable(vtable)?;
+
                 Ok(Some(mem_pos))
             }
 

src/librustc_mir/interpret/place.rs

@@ -1130,10 +1130,9 @@ where
 
         // More sanity checks
         if cfg!(debug_assertions) {
-            let (size, align) = self.read_size_and_align_from_vtable(vtable)?;
-            assert_eq!(size, layout.pref_pos.size);
+            let mem_pos = self.read_mem_pos_from_vtable(vtable)?;
             // only ABI alignment is preserved
-            assert_eq!(align, layout.pref_pos.align.abi);
+            assert_eq!(mem_pos, layout.pref_pos.mem_pos());
         }
 
         let mplace = MPlaceTy {

src/librustc_mir/interpret/traits.rs

@@ -1,5 +1,5 @@
 use rustc::ty::{self, Ty, Instance, TypeFoldable};
-use rustc::ty::layout::{Size, Align, LayoutOf, HasDataLayout};
+use rustc::ty::layout::{Size, MemoryPosition, Align, LayoutOf, HasDataLayout};
 use rustc::mir::interpret::{Scalar, Pointer, InterpResult, PointerArithmetic,};
 
 use super::{InterpCx, Machine, MemoryKind, FnVal};
@@ -123,10 +123,10 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         Ok((drop_instance, ty))
     }
 
-    pub fn read_size_and_align_from_vtable(
+    pub fn read_mem_pos_from_vtable(
         &self,
         vtable: Scalar<M::PointerTag>,
-    ) -> InterpResult<'tcx, (Size, Align)> {
+    ) -> InterpResult<'tcx, MemoryPosition> {
         let ptr_pos = self.pointer_pos().mem_pos();
         // We check for size = 3*ptr_size, that covers the drop fn (unused here),
         // the size, and the align (which we read below).
@@ -150,6 +150,6 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             throw_ub_format!("invalid vtable: \
                 size is bigger than largest supported object");
         }
-        Ok((Size::from_bytes(size), Align::from_bytes(align).unwrap()))
+        Ok(MemoryPosition::new(Size::from_bytes(size), Align::from_bytes(align).unwrap()))
     }
 }

src/librustc_mir/interpret/validity.rs

@@ -276,7 +276,7 @@ impl<'rt, 'mir, 'tcx, M: Machine<'mir, 'tcx>> ValidityVisitor<'rt, 'mir, 'tcx, M
                 );
                 try_validation!(self.ecx.read_drop_type_from_vtable(vtable),
                     "invalid drop fn in vtable", self.path);
-                try_validation!(self.ecx.read_size_and_align_from_vtable(vtable),
+                try_validation!(self.ecx.read_mem_pos_from_vtable(vtable),
                     "invalid size or align in vtable", self.path);
                 // FIXME: More checks for the vtable.
             }