Revert "Rollup merge of #98582 - oli-obk:unconstrained_opaque_type, r=estebank"

This reverts commit 6f8fb911ad504b77549cf3256a09465621beab9d, reversing
changes made to 7210e46dc69a4b197a313d093fe145722c248b7d.

src/base.rs

@@ -825,7 +825,6 @@ pub(crate) fn codegen_place<'tcx>(
                     cplace = cplace.place_deref(fx);
                 }
             }
-            PlaceElem::OpaqueCast(ty) => cplace = cplace.place_opaque_cast(fx, ty),
             PlaceElem::Field(field, _ty) => {
                 cplace = cplace.place_field(fx, field);
             }

src/value_and_place.rs

@@ -615,14 +615,6 @@ impl<'tcx> CPlace<'tcx> {
         }
     }
 
-    pub(crate) fn place_opaque_cast(
-        self,
-        fx: &mut FunctionCx<'_, '_, 'tcx>,
-        ty: Ty<'tcx>,
-    ) -> CPlace<'tcx> {
-        CPlace { inner: self.inner, layout: fx.layout_of(ty) }
-    }
-
     pub(crate) fn place_field(
         self,
         fx: &mut FunctionCx<'_, '_, 'tcx>,