bjoernager/rust
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Move check to existing pass

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This alters the diagnostics a bit, as the trait method is still stable.
The only thing this check does is ensure that compilation fails if a
trait implementation is declared const-stable.
This commit is contained in:
Jacob Pratt 2022-02-22 14:54:47 -05:00 • committed by Oli Scherer
parent f0620c9503
commit 5ff331142e
7 changed files with 61 additions and 157 deletions
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82
compiler/rustc_passes/src/stability.rs
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@ -9,7 +9,6 @@ use rustc_hir::def::{DefKind, Res};
use rustc_hir::def_id::{LocalDefId, CRATE_DEF_ID};
use rustc_hir::hir_id::CRATE_HIR_ID;
use rustc_hir::intravisit::{self, Visitor};
use rustc_hir::itemlikevisit::ItemLikeVisitor;
use rustc_hir::{FieldDef, Generics, HirId, Item, TraitRef, Ty, TyKind, Variant};
use rustc_middle::hir::nested_filter;
use rustc_middle::middle::privacy::AccessLevels;
@ -606,44 +605,6 @@ impl<'tcx> Visitor<'tcx> for MissingStabilityAnnotations<'tcx> {
// stable (assuming they have not inherited instability from their parent).
}
struct CheckStableConstImplTrait<'tcx> {
tcx: TyCtxt<'tcx>,
}
impl<'tcx> ItemLikeVisitor<'tcx> for CheckStableConstImplTrait<'tcx> {
fn visit_item(&mut self, item: &'tcx Item<'tcx>) {
if !matches!(
item.kind,
hir::ItemKind::Impl(hir::Impl {
of_trait: Some(_),
constness: hir::Constness::Const,
..
})
) {
return;
}
if self.tcx.lookup_const_stability(item.def_id).map_or(false, |stab| stab.is_const_stable())
{
self.tcx
.sess
.struct_span_err(item.span, "trait implementations cannot be const stable yet")
.note("see issue #67792 <https://github.com/rust-lang/rust/issues/67792> for more information")
.emit();
}
}
fn visit_trait_item(&mut self, _trait_item: &'tcx hir::TraitItem<'tcx>) {
// Nothing to do here.
}
fn visit_impl_item(&mut self, _impl_item: &'tcx hir::ImplItem<'tcx>) {
// Nothing to do here.
}
fn visit_foreign_item(&mut self, _foreign_item: &'tcx hir::ForeignItem<'tcx>) {
// Nothing to do here.
}
}
fn stability_index(tcx: TyCtxt<'_>, (): ()) -> Index {
let mut index = Index {
stab_map: Default::default(),
@ -748,16 +709,23 @@ impl<'tcx> Visitor<'tcx> for Checker<'tcx> {
// For implementations of traits, check the stability of each item
// individually as it's possible to have a stable trait with unstable
// items.
hir::ItemKind::Impl(hir::Impl { of_trait: Some(ref t), self_ty, items, .. }) => {
if self.tcx.features().staged_api {
hir::ItemKind::Impl(hir::Impl {
of_trait: Some(ref t),
self_ty,
items,
constness,
..
}) => {
let features = self.tcx.features();
if features.staged_api {
let attrs = self.tcx.hir().attrs(item.hir_id());
let (stab, const_stab) = attr::find_stability(&self.tcx.sess, attrs, item.span);
// If this impl block has an #[unstable] attribute, give an
// error if all involved types and traits are stable, because
// it will have no effect.
// See: https://github.com/rust-lang/rust/issues/55436
let attrs = self.tcx.hir().attrs(item.hir_id());
if let (Some((Stability { level: attr::Unstable { .. }, .. }, span)), _) =
attr::find_stability(&self.tcx.sess, attrs, item.span)
{
if let Some((Stability { level: attr::Unstable { .. }, .. }, span)) = stab {
let mut c = CheckTraitImplStable { tcx: self.tcx, fully_stable: true };
c.visit_ty(self_ty);
c.visit_trait_ref(t);
@ -773,6 +741,19 @@ impl<'tcx> Visitor<'tcx> for Checker<'tcx> {
);
}
}
// `#![feature(const_trait_impl)]` is unstable, so any impl declared stable
// needs to have an error emitted.
if features.const_trait_impl
&& constness == hir::Constness::Const
&& const_stab.map_or(false, |(stab, _)| stab.is_const_stable())
{
self.tcx
.sess
.struct_span_err(item.span, "trait implementations cannot be const stable yet")
.note("see issue #67792 <https://github.com/rust-lang/rust/issues/67792> for more information")
.emit();
}
}
for impl_item_ref in *items {
@ -864,17 +845,6 @@ impl<'tcx> Visitor<'tcx> for CheckTraitImplStable<'tcx> {
}
}
pub fn check_const_impl_trait(tcx: TyCtxt<'_>) {
let features = tcx.features(); // FIXME How cheap is this call?
// Both feature gates have to be enabled for this check to have any effect.
if !features.staged_api || !features.const_trait_impl {
return;
}
let mut visitor = CheckStableConstImplTrait { tcx };
tcx.hir().visit_all_item_likes(&mut visitor);
}
/// Given the list of enabled features that were not language features (i.e., that
/// were expected to be library features), and the list of features used from
/// libraries, identify activated features that don't exist and error about them.