src/librustc_mir/monomorphize/mod.rs

   1 use rustc_middle::traits;
   2 use rustc_middle::ty::adjustment::CustomCoerceUnsized;
   3 use rustc_middle::ty::{self, Ty, TyCtxt};
   4
   5 use rustc_hir::lang_items::LangItem;
   6
   7 pub mod collector;
   8 pub mod partitioning;
   9 pub mod polymorphize;
  10
  11 pub fn custom_coerce_unsize_info<'tcx>(
  12     tcx: TyCtxt<'tcx>,
  13     source_ty: Ty<'tcx>,
  14     target_ty: Ty<'tcx>,
  15 ) -> CustomCoerceUnsized {
  16     let def_id = tcx.require_lang_item(LangItem::CoerceUnsized, None);
  17
  18     let trait_ref = ty::Binder::bind(ty::TraitRef {
  19         def_id,
  20         substs: tcx.mk_substs_trait(source_ty, &[target_ty.into()]),
  21     });
  22
  23     match tcx.codegen_fulfill_obligation((ty::ParamEnv::reveal_all(), trait_ref)) {
  24         Ok(traits::ImplSourceUserDefined(traits::ImplSourceUserDefinedData {
  25             impl_def_id,
  26             ..
  27         })) => tcx.coerce_unsized_info(impl_def_id).custom_kind.unwrap(),
  28         impl_source => {
  29             bug!("invalid `CoerceUnsized` impl_source: {:?}", impl_source);
  30         }
  31     }
  32 }