compiler/rustc_trait_selection/src/solve/infcx_ext.rs

   1 use rustc_infer::infer::at::ToTrace;
   2 use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
   3 use rustc_infer::infer::{InferCtxt, InferOk, LateBoundRegionConversionTime};
   4 use rustc_infer::traits::query::NoSolution;
   5 use rustc_infer::traits::ObligationCause;
   6 use rustc_middle::infer::unify_key::{ConstVariableOrigin, ConstVariableOriginKind};
   7 use rustc_middle::ty::{self, Ty, TypeFoldable};
   8 use rustc_span::DUMMY_SP;
   9
  10 use super::Goal;
  11
  12 /// Methods used inside of the canonical queries of the solver.
  13 ///
  14 /// Most notably these do not care about diagnostics information.
  15 /// If you find this while looking for methods to use outside of the
  16 /// solver, you may look at the implementation of these method for
  17 /// help.
  18 pub(super) trait InferCtxtExt<'tcx> {
  19     fn next_ty_infer(&self) -> Ty<'tcx>;
  20     fn next_const_infer(&self, ty: Ty<'tcx>) -> ty::Const<'tcx>;
  21
  22     fn eq<T: ToTrace<'tcx>>(
  23         &self,
  24         param_env: ty::ParamEnv<'tcx>,
  25         lhs: T,
  26         rhs: T,
  27     ) -> Result<Vec<Goal<'tcx, ty::Predicate<'tcx>>>, NoSolution>;
  28
  29     fn instantiate_bound_vars_with_infer<T: TypeFoldable<'tcx> + Copy>(
  30         &self,
  31         value: ty::Binder<'tcx, T>,
  32     ) -> T;
  33 }
  34
  35 impl<'tcx> InferCtxtExt<'tcx> for InferCtxt<'tcx> {
  36     fn next_ty_infer(&self) -> Ty<'tcx> {
  37         self.next_ty_var(TypeVariableOrigin {
  38             kind: TypeVariableOriginKind::MiscVariable,
  39             span: DUMMY_SP,
  40         })
  41     }
  42     fn next_const_infer(&self, ty: Ty<'tcx>) -> ty::Const<'tcx> {
  43         self.next_const_var(
  44             ty,
  45             ConstVariableOrigin { kind: ConstVariableOriginKind::MiscVariable, span: DUMMY_SP },
  46         )
  47     }
  48
  49     #[instrument(level = "debug", skip(self, param_env), ret)]
  50     fn eq<T: ToTrace<'tcx>>(
  51         &self,
  52         param_env: ty::ParamEnv<'tcx>,
  53         lhs: T,
  54         rhs: T,
  55     ) -> Result<Vec<Goal<'tcx, ty::Predicate<'tcx>>>, NoSolution> {
  56         self.at(&ObligationCause::dummy(), param_env)
  57             .define_opaque_types(false)
  58             .eq(lhs, rhs)
  59             .map(|InferOk { value: (), obligations }| {
  60                 obligations.into_iter().map(|o| o.into()).collect()
  61             })
  62             .map_err(|e| {
  63                 debug!(?e, "failed to equate");
  64                 NoSolution
  65             })
  66     }
  67
  68     fn instantiate_bound_vars_with_infer<T: TypeFoldable<'tcx> + Copy>(
  69         &self,
  70         value: ty::Binder<'tcx, T>,
  71     ) -> T {
  72         self.replace_bound_vars_with_fresh_vars(
  73             DUMMY_SP,
  74             LateBoundRegionConversionTime::HigherRankedType,
  75             value,
  76         )
  77     }
  78 }