bjoernager/rust
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Auto merge of #97177 - oli-obk:const-stability, r=davidtwco

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Implement proper stability check for const impl Trait, fall back to unstable const when undeclared

Continuation of #93960

`@jhpratt` it looks to me like the test was simply not testing for the failure you were looking for? Your checks actually do the right thing for const traits?
This commit is contained in:
bors 2022-05-22 06:47:36 +00:00
commit acfd327fd4
22 changed files with 259 additions and 168 deletions
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43
compiler/rustc_passes/src/stability.rs
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@ -147,7 +147,7 @@ impl<'a, 'tcx> Annotator<'a, 'tcx> {
// Propagate unstability. This can happen even for non-staged-api crates in case
// -Zforce-unstable-if-unmarked is set.
if let Some(stab) = self.parent_stab {
if inherit_deprecation.yes() && stab.level.is_unstable() {
if inherit_deprecation.yes() && stab.is_unstable() {
self.index.stab_map.insert(def_id, stab);
}
}
@ -190,7 +190,7 @@ impl<'a, 'tcx> Annotator<'a, 'tcx> {
if const_stab.is_none() {
debug!("annotate: const_stab not found, parent = {:?}", self.parent_const_stab);
if let Some(parent) = self.parent_const_stab {
if parent.level.is_unstable() {
if parent.is_const_unstable() {
self.index.const_stab_map.insert(def_id, parent);
}
}
@ -272,9 +272,7 @@ impl<'a, 'tcx> Annotator<'a, 'tcx> {
if stab.is_none() {
debug!("annotate: stab not found, parent = {:?}", self.parent_stab);
if let Some(stab) = self.parent_stab {
if inherit_deprecation.yes() && stab.level.is_unstable()
|| inherit_from_parent.yes()
{
if inherit_deprecation.yes() && stab.is_unstable() || inherit_from_parent.yes() {
self.index.stab_map.insert(def_id, stab);
}
}
@ -532,7 +530,8 @@ impl<'tcx> MissingStabilityAnnotations<'tcx> {
return;
}
let is_const = self.tcx.is_const_fn(def_id.to_def_id());
let is_const = self.tcx.is_const_fn(def_id.to_def_id())
|| self.tcx.is_const_trait_impl_raw(def_id.to_def_id());
let is_stable = self
.tcx
.lookup_stability(def_id)
@ -710,16 +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);
@ -735,6 +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 {