1 //! Some helper functions for `AutoDeref`
2 use super::method::MethodCallee;
3 use super::{FnCtxt, PlaceOp};
5 use rustc_infer::infer::InferOk;
6 use rustc_middle::ty::adjustment::{Adjust, Adjustment, OverloadedDeref};
7 use rustc_middle::ty::{self, Ty};
9 use rustc_trait_selection::autoderef::{Autoderef, AutoderefKind};
13 impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
14 pub fn autoderef(&'a self, span: Span, base_ty: Ty<'tcx>) -> Autoderef<'a, 'tcx> {
15 Autoderef::new(self, self.param_env, self.body_id, span, base_ty, span)
18 /// Like `autoderef`, but provides a custom `Span` to use for calls to
19 /// an overloaded `Deref` operator
20 pub fn autoderef_overloaded_span(
24 overloaded_span: Span,
25 ) -> Autoderef<'a, 'tcx> {
26 Autoderef::new(self, self.param_env, self.body_id, span, base_ty, overloaded_span)
29 pub fn try_overloaded_deref(
33 ) -> Option<InferOk<'tcx, MethodCallee<'tcx>>> {
34 self.try_overloaded_place_op(span, base_ty, &[], PlaceOp::Deref)
37 /// Returns the adjustment steps.
38 pub fn adjust_steps(&self, autoderef: &Autoderef<'a, 'tcx>) -> Vec<Adjustment<'tcx>> {
39 self.register_infer_ok_obligations(self.adjust_steps_as_infer_ok(autoderef))
42 pub fn adjust_steps_as_infer_ok(
44 autoderef: &Autoderef<'a, 'tcx>,
45 ) -> InferOk<'tcx, Vec<Adjustment<'tcx>>> {
46 let mut obligations = vec![];
47 let steps = autoderef.steps();
49 steps.iter().skip(1).map(|&(ty, _)| ty).chain(iter::once(autoderef.final_ty(false)));
50 let steps: Vec<_> = steps
52 .map(|&(source, kind)| {
53 if let AutoderefKind::Overloaded = kind {
54 self.try_overloaded_deref(autoderef.span(), source).and_then(
55 |InferOk { value: method, obligations: o }| {
56 obligations.extend(o);
57 if let ty::Ref(region, _, mutbl) = *method.sig.output().kind() {
58 Some(OverloadedDeref {
61 span: autoderef.overloaded_span(),
73 .map(|(autoderef, target)| Adjustment { kind: Adjust::Deref(autoderef), target })
76 InferOk { obligations, value: steps }