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use crate::traits::query::evaluate_obligation::InferCtxtExt as _;
use crate::traits::{self, ObligationCtxt};
use rustc_hir::def_id::DefId;
use rustc_hir::lang_items::LangItem;
use rustc_middle::arena::ArenaAllocatable;
use rustc_middle::infer::canonical::{Canonical, CanonicalQueryResponse, QueryResponse};
use rustc_middle::traits::query::Fallible;
use rustc_middle::ty::{self, Ty, TyCtxt, TypeFoldable, TypeVisitableExt};
use rustc_middle::ty::{GenericArg, ToPredicate};
use rustc_span::DUMMY_SP;
use std::fmt::Debug;
pub use rustc_infer::infer::*;
pub trait InferCtxtExt<'tcx> {
fn type_is_copy_modulo_regions(&self, param_env: ty::ParamEnv<'tcx>, ty: Ty<'tcx>) -> bool;
fn type_is_sized_modulo_regions(&self, param_env: ty::ParamEnv<'tcx>, ty: Ty<'tcx>) -> bool;
/// Check whether a `ty` implements given trait(trait_def_id).
/// The inputs are:
///
/// - the def-id of the trait
/// - the type parameters of the trait, including the self-type
/// - the parameter environment
///
/// Invokes `evaluate_obligation`, so in the event that evaluating
/// `Ty: Trait` causes overflow, EvaluatedToRecur (or EvaluatedToUnknown)
/// will be returned.
fn type_implements_trait(
&self,
trait_def_id: DefId,
params: impl IntoIterator<Item: Into<GenericArg<'tcx>>>,
param_env: ty::ParamEnv<'tcx>,
) -> traits::EvaluationResult;
}
impl<'tcx> InferCtxtExt<'tcx> for InferCtxt<'tcx> {
fn type_is_copy_modulo_regions(&self, param_env: ty::ParamEnv<'tcx>, ty: Ty<'tcx>) -> bool {
let ty = self.resolve_vars_if_possible(ty);
if !(param_env, ty).has_infer() {
return ty.is_copy_modulo_regions(self.tcx, param_env);
}
let copy_def_id = self.tcx.require_lang_item(LangItem::Copy, None);
// This can get called from typeck (by euv), and `moves_by_default`
// rightly refuses to work with inference variables, but
// moves_by_default has a cache, which we want to use in other
// cases.
traits::type_known_to_meet_bound_modulo_regions(self, param_env, ty, copy_def_id)
}
fn type_is_sized_modulo_regions(&self, param_env: ty::ParamEnv<'tcx>, ty: Ty<'tcx>) -> bool {
let lang_item = self.tcx.require_lang_item(LangItem::Sized, None);
traits::type_known_to_meet_bound_modulo_regions(self, param_env, ty, lang_item)
}
#[instrument(level = "debug", skip(self, params), ret)]
fn type_implements_trait(
&self,
trait_def_id: DefId,
params: impl IntoIterator<Item: Into<GenericArg<'tcx>>>,
param_env: ty::ParamEnv<'tcx>,
) -> traits::EvaluationResult {
let trait_ref = ty::TraitRef::new(self.tcx, trait_def_id, params);
let obligation = traits::Obligation {
cause: traits::ObligationCause::dummy(),
param_env,
recursion_depth: 0,
predicate: ty::Binder::dummy(trait_ref).without_const().to_predicate(self.tcx),
};
self.evaluate_obligation(&obligation).unwrap_or(traits::EvaluationResult::EvaluatedToErr)
}
}
pub trait InferCtxtBuilderExt<'tcx> {
fn enter_canonical_trait_query<K, R>(
&mut self,
canonical_key: &Canonical<'tcx, K>,
operation: impl FnOnce(&ObligationCtxt<'_, 'tcx>, K) -> Fallible<R>,
) -> Fallible<CanonicalQueryResponse<'tcx, R>>
where
K: TypeFoldable<TyCtxt<'tcx>>,
R: Debug + TypeFoldable<TyCtxt<'tcx>>,
Canonical<'tcx, QueryResponse<'tcx, R>>: ArenaAllocatable<'tcx>;
}
impl<'tcx> InferCtxtBuilderExt<'tcx> for InferCtxtBuilder<'tcx> {
/// The "main method" for a canonicalized trait query. Given the
/// canonical key `canonical_key`, this method will create a new
/// inference context, instantiate the key, and run your operation
/// `op`. The operation should yield up a result (of type `R`) as
/// well as a set of trait obligations that must be fully
/// satisfied. These obligations will be processed and the
/// canonical result created.
///
/// Returns `NoSolution` in the event of any error.
///
/// (It might be mildly nicer to implement this on `TyCtxt`, and
/// not `InferCtxtBuilder`, but that is a bit tricky right now.
/// In part because we would need a `for<'tcx>` sort of
/// bound for the closure and in part because it is convenient to
/// have `'tcx` be free on this function so that we can talk about
/// `K: TypeFoldable<TyCtxt<'tcx>>`.)
fn enter_canonical_trait_query<K, R>(
&mut self,
canonical_key: &Canonical<'tcx, K>,
operation: impl FnOnce(&ObligationCtxt<'_, 'tcx>, K) -> Fallible<R>,
) -> Fallible<CanonicalQueryResponse<'tcx, R>>
where
K: TypeFoldable<TyCtxt<'tcx>>,
R: Debug + TypeFoldable<TyCtxt<'tcx>>,
Canonical<'tcx, QueryResponse<'tcx, R>>: ArenaAllocatable<'tcx>,
{
let (infcx, key, canonical_inference_vars) =
self.build_with_canonical(DUMMY_SP, canonical_key);
let ocx = ObligationCtxt::new(&infcx);
let value = operation(&ocx, key)?;
ocx.make_canonicalized_query_response(canonical_inference_vars, value)
}
}
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