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Some early clean-ups in method probe

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This commit is contained in:
Michael Goulet 2024-03-10 18:50:55 +00:00
parent fb898629a2
commit c13af7db21
1 changed files with 8 additions and 51 deletions
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59
compiler/rustc_hir_typeck/src/method/probe.rs
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@ -21,7 +21,7 @@
use rustc_middle::ty::AssocItem;
use rustc_middle::ty::GenericParamDefKind;
use rustc_middle::ty::ToPredicate;
use rustc_middle::ty::{self, ParamEnvAnd, Ty, TyCtxt, TypeFoldable, TypeVisitableExt};
use rustc_middle::ty::{self, ParamEnvAnd, Ty, TyCtxt, TypeVisitableExt};
use rustc_middle::ty::{GenericArgs, GenericArgsRef};
use rustc_session::lint;
use rustc_span::def_id::DefId;
@ -745,7 +745,6 @@ fn assemble_inherent_impl_probe(&mut self, impl_def_id: DefId) {
}
let (impl_ty, impl_args) = self.impl_ty_and_args(impl_def_id);
let impl_ty = impl_ty.instantiate(self.tcx, impl_args);
debug!("impl_ty: {:?}", impl_ty);
@ -818,7 +817,7 @@ fn assemble_inherent_candidates_from_object(&mut self, self_ty: Ty<'tcx>) {
return;
}
let new_trait_ref = this.instantiate_bound_regions_with_erased(new_trait_ref);
let new_trait_ref = this.tcx.instantiate_bound_regions_with_erased(new_trait_ref);
let (xform_self_ty, xform_ret_ty) =
this.xform_self_ty(item, new_trait_ref.self_ty(), new_trait_ref.args);
@ -929,27 +928,12 @@ fn assemble_extension_candidates_for_all_traits(&mut self) {
}
}
fn matches_return_type(
&self,
method: ty::AssocItem,
self_ty: Option<Ty<'tcx>>,
expected: Ty<'tcx>,
) -> bool {
fn matches_return_type(&self, method: ty::AssocItem, expected: Ty<'tcx>) -> bool {
match method.kind {
ty::AssocKind::Fn => self.probe(|_| {
let args = self.fresh_args_for_item(self.span, method.def_id);
let fty = self.tcx.fn_sig(method.def_id).instantiate(self.tcx, args);
let fty = self.instantiate_binder_with_fresh_vars(self.span, infer::FnCall, fty);
if let Some(self_ty) = self_ty {
if self
.at(&ObligationCause::dummy(), self.param_env)
.sup(DefineOpaqueTypes::No, fty.inputs()[0], self_ty)
.is_err()
{
return false;
}
}
self.can_sub(self.param_env, fty.output(), expected)
}),
_ => false,
@ -1040,7 +1024,7 @@ fn candidate_method_names(
.filter(|candidate| candidate_filter(&candidate.item))
.filter(|candidate| {
if let Some(return_ty) = self.return_type {
self.matches_return_type(candidate.item, None, return_ty)
self.matches_return_type(candidate.item, return_ty)
} else {
true
}
@ -1894,40 +1878,13 @@ fn xform_method_sig(&self, method: DefId, args: GenericArgsRef<'tcx>) -> ty::FnS
fn_sig.instantiate(self.tcx, args)
};
self.instantiate_bound_regions_with_erased(xform_fn_sig)
self.tcx.instantiate_bound_regions_with_erased(xform_fn_sig)
}
/// Gets the type of an impl and generate generic parameters with inference vars.
fn impl_ty_and_args(
&self,
impl_def_id: DefId,
) -> (ty::EarlyBinder<Ty<'tcx>>, GenericArgsRef<'tcx>) {
(self.tcx.type_of(impl_def_id), self.fresh_args_for_item(self.span, impl_def_id))
}
/// Replaces late-bound-regions bound by `value` with `'static` using
/// `ty::instantiate_bound_regions_with_erased`.
///
/// This is only a reasonable thing to do during the *probe* phase, not the *confirm* phase, of
/// method matching. It is reasonable during the probe phase because we don't consider region
/// relationships at all. Therefore, we can just replace all the region variables with 'static
/// rather than creating fresh region variables. This is nice for two reasons:
///
/// 1. Because the numbers of the region variables would otherwise be fairly unique to this
/// particular method call, it winds up creating fewer types overall, which helps for memory
/// usage. (Admittedly, this is a rather small effect, though measurable.)
///
/// 2. It makes it easier to deal with higher-ranked trait bounds, because we can replace any
/// late-bound regions with 'static. Otherwise, if we were going to replace late-bound
/// regions with actual region variables as is proper, we'd have to ensure that the same
/// region got replaced with the same variable, which requires a bit more coordination
/// and/or tracking the instantiations and
/// so forth.
fn instantiate_bound_regions_with_erased<T>(&self, value: ty::Binder<'tcx, T>) -> T
where
T: TypeFoldable<TyCtxt<'tcx>>,
{
self.tcx.instantiate_bound_regions_with_erased(value)
fn impl_ty_and_args(&self, impl_def_id: DefId) -> (Ty<'tcx>, GenericArgsRef<'tcx>) {
let args = self.fresh_args_for_item(self.span, impl_def_id);
(self.tcx.type_of(impl_def_id).instantiate(self.tcx, args), args)
}
/// Determine if the given associated item type is relevant in the current context.