compiler/rustc_mir/src/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 pub mod util;
  11
  12 fn custom_coerce_unsize_info<'tcx>(
  13     tcx: TyCtxt<'tcx>,
  14     source_ty: Ty<'tcx>,
  15     target_ty: Ty<'tcx>,
  16 ) -> CustomCoerceUnsized {
  17     let def_id = tcx.require_lang_item(LangItem::CoerceUnsized, None);
  18
  19     let trait_ref = ty::Binder::dummy(ty::TraitRef {
  20         def_id,
  21         substs: tcx.mk_substs_trait(source_ty, &[target_ty.into()]),
  22     });
  23
  24     match tcx.codegen_fulfill_obligation((ty::ParamEnv::reveal_all(), trait_ref)) {
  25         Ok(traits::ImplSource::UserDefined(traits::ImplSourceUserDefinedData {
  26             impl_def_id,
  27             ..
  28         })) => tcx.coerce_unsized_info(impl_def_id).custom_kind.unwrap(),
  29         impl_source => {
  30             bug!("invalid `CoerceUnsized` impl_source: {:?}", impl_source);
  31         }
  32     }
  33 }