src/librustc_mir/monomorphize/mod.rs

   1 use rustc::traits;
   2 use rustc::ty::adjustment::CustomCoerceUnsized;
   3 use rustc::ty::{self, Ty, TyCtxt};
   4
   5 pub mod collector;
   6 pub mod partitioning;
   7
   8 pub fn custom_coerce_unsize_info<'tcx>(
   9     tcx: TyCtxt<'tcx>,
  10     source_ty: Ty<'tcx>,
  11     target_ty: Ty<'tcx>,
  12 ) -> CustomCoerceUnsized {
  13     let def_id = tcx.lang_items().coerce_unsized_trait().unwrap();
  14
  15     let trait_ref = ty::Binder::bind(ty::TraitRef {
  16         def_id: def_id,
  17         substs: tcx.mk_substs_trait(source_ty, &[target_ty.into()]),
  18     });
  19
  20     match tcx.codegen_fulfill_obligation((ty::ParamEnv::reveal_all(), trait_ref)) {
  21         traits::VtableImpl(traits::VtableImplData { impl_def_id, .. }) => {
  22             tcx.coerce_unsized_info(impl_def_id).custom_kind.unwrap()
  23         }
  24         vtable => {
  25             bug!("invalid `CoerceUnsized` vtable: {:?}", vtable);
  26         }
  27     }
  28 }