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Rollup merge of #136434 - RalfJung:rustc_allowed_through_unstable_modules-deprecation-required, r=compiler-errors

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rustc_allowed_through_unstable_modules: require deprecation message

This changes the `#[rustc_allowed_through_unstable_modules]` attribute so that a deprecation message (ideally directing people towards the stable path) is required.
This commit is contained in:
Matthias Krüger 2025-02-02 18:05:25 +01:00 • committed by GitHub
commit 961bf7ffa6
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GPG key ID: B5690EEEBB952194
12 changed files with 107 additions and 125 deletions
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15
compiler/rustc_attr_data_structures/src/stability.rs
View file

@ -101,16 +101,6 @@ impl PartialConstStability {
}
}
#[derive(Encodable, Decodable, PartialEq, Copy, Clone, Debug, Eq, Hash)]
#[derive(HashStable_Generic)]
pub enum AllowedThroughUnstableModules {
/// This does not get a deprecation warning. We still generally would prefer people to use the
/// fully stable path, and a warning will likely be emitted in the future.
WithoutDeprecation,
/// Emit the given deprecation warning.
WithDeprecation(Symbol),
}
/// The available stability levels.
#[derive(Encodable, Decodable, PartialEq, Copy, Clone, Debug, Eq, Hash)]
#[derive(HashStable_Generic)]
@ -147,8 +137,9 @@ pub enum StabilityLevel {
Stable {
/// Rust release which stabilized this feature.
since: StableSince,
/// This is `Some` if this item allowed to be referred to on stable via unstable modules.
allowed_through_unstable_modules: Option<AllowedThroughUnstableModules>,
/// This is `Some` if this item allowed to be referred to on stable via unstable modules;
/// the `Symbol` is the deprecation message printed in that case.
allowed_through_unstable_modules: Option<Symbol>,
},
}

18
compiler/rustc_attr_parsing/src/attributes/stability.rs
View file

@ -6,12 +6,12 @@ use rustc_ast::MetaItem;
use rustc_ast::attr::AttributeExt;
use rustc_ast_pretty::pprust;
use rustc_attr_data_structures::{
AllowedThroughUnstableModules, ConstStability, DefaultBodyStability, Stability, StabilityLevel,
StableSince, UnstableReason, VERSION_PLACEHOLDER,
ConstStability, DefaultBodyStability, Stability, StabilityLevel, StableSince, UnstableReason,
VERSION_PLACEHOLDER,
};
use rustc_errors::ErrorGuaranteed;
use rustc_session::Session;
use rustc_span::{Span, Symbol, sym};
use rustc_span::{Span, Symbol, kw, sym};
use crate::attributes::util::UnsupportedLiteralReason;
use crate::{parse_version, session_diagnostics};
@ -29,10 +29,14 @@ pub fn find_stability(
for attr in attrs {
match attr.name_or_empty() {
sym::rustc_allowed_through_unstable_modules => {
allowed_through_unstable_modules = Some(match attr.value_str() {
Some(msg) => AllowedThroughUnstableModules::WithDeprecation(msg),
None => AllowedThroughUnstableModules::WithoutDeprecation,
})
// The value is mandatory, but avoid ICEs in case such code reaches this function.
allowed_through_unstable_modules = Some(attr.value_str().unwrap_or_else(|| {
sess.dcx().span_delayed_bug(
item_sp,
"`#[rustc_allowed_through_unstable_modules]` without deprecation message",
);
kw::Empty
}))
}
sym::unstable => {
if stab.is_some() {

2
compiler/rustc_feature/src/builtin_attrs.rs
View file

@ -616,7 +616,7 @@ pub const BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
EncodeCrossCrate::No, "allow_internal_unsafe side-steps the unsafe_code lint",
),
rustc_attr!(
rustc_allowed_through_unstable_modules, Normal, template!(Word, NameValueStr: "deprecation message"),
rustc_allowed_through_unstable_modules, Normal, template!(NameValueStr: "deprecation message"),
WarnFollowing, EncodeCrossCrate::No,
"rustc_allowed_through_unstable_modules special cases accidental stabilizations of stable items \
through unstable paths"

154
compiler/rustc_passes/src/stability.rs
View file

@ -5,8 +5,8 @@ use std::mem::replace;
use std::num::NonZero;
use rustc_attr_parsing::{
self as attr, AllowedThroughUnstableModules, ConstStability, DeprecatedSince, Stability,
StabilityLevel, StableSince, UnstableReason, VERSION_PLACEHOLDER,
self as attr, ConstStability, DeprecatedSince, Stability, StabilityLevel, StableSince,
UnstableReason, VERSION_PLACEHOLDER,
};
use rustc_data_structures::fx::FxIndexMap;
use rustc_data_structures::unord::{ExtendUnord, UnordMap, UnordSet};
@ -880,7 +880,7 @@ impl<'tcx> Visitor<'tcx> for Checker<'tcx> {
if item_is_allowed {
// The item itself is allowed; check whether the path there is also allowed.
let is_allowed_through_unstable_modules: Option<AllowedThroughUnstableModules> =
let is_allowed_through_unstable_modules: Option<Symbol> =
self.tcx.lookup_stability(def_id).and_then(|stab| match stab.level {
StabilityLevel::Stable { allowed_through_unstable_modules, .. } => {
allowed_through_unstable_modules
@ -888,84 +888,80 @@ impl<'tcx> Visitor<'tcx> for Checker<'tcx> {
_ => None,
});
if is_allowed_through_unstable_modules.is_none() {
// Check parent modules stability as well if the item the path refers to is itself
// stable. We only emit warnings for unstable path segments if the item is stable
// or allowed because stability is often inherited, so the most common case is that
// both the segments and the item are unstable behind the same feature flag.
//
// We check here rather than in `visit_path_segment` to prevent visiting the last
// path segment twice
//
// We include special cases via #[rustc_allowed_through_unstable_modules] for items
// that were accidentally stabilized through unstable paths before this check was
// added, such as `core::intrinsics::transmute`
let parents = path.segments.iter().rev().skip(1);
for path_segment in parents {
if let Some(def_id) = path_segment.res.opt_def_id() {
// use `None` for id to prevent deprecation check
self.tcx.check_stability_allow_unstable(
def_id,
None,
path.span,
None,
if is_unstable_reexport(self.tcx, id) {
AllowUnstable::Yes
} else {
AllowUnstable::No
},
);
}
}
} else if let Some(AllowedThroughUnstableModules::WithDeprecation(deprecation)) =
is_allowed_through_unstable_modules
{
// Similar to above, but we cannot use `check_stability_allow_unstable` as that would
// immediately show the stability error. We just want to know the result and disaplay
// our own kind of error.
let parents = path.segments.iter().rev().skip(1);
for path_segment in parents {
if let Some(def_id) = path_segment.res.opt_def_id() {
// use `None` for id to prevent deprecation check
let eval_result = self.tcx.eval_stability_allow_unstable(
def_id,
None,
path.span,
None,
if is_unstable_reexport(self.tcx, id) {
AllowUnstable::Yes
} else {
AllowUnstable::No
},
);
let is_allowed = matches!(eval_result, EvalResult::Allow);
if !is_allowed {
// Calculating message for lint involves calling `self.def_path_str`,
// which will by default invoke the expensive `visible_parent_map` query.
// Skip all that work if the lint is allowed anyway.
if self.tcx.lint_level_at_node(DEPRECATED, id).0
== lint::Level::Allow
{
return;
}
// Show a deprecation message.
let def_path =
with_no_trimmed_paths!(self.tcx.def_path_str(def_id));
let def_kind = self.tcx.def_descr(def_id);
let diag = Deprecated {
sub: None,
kind: def_kind.to_owned(),
path: def_path,
note: Some(deprecation),
since_kind: lint::DeprecatedSinceKind::InEffect,
};
self.tcx.emit_node_span_lint(
DEPRECATED,
id,
method_span.unwrap_or(path.span),
diag,
// Check parent modules stability as well if the item the path refers to is itself
// stable. We only emit errors for unstable path segments if the item is stable
// or allowed because stability is often inherited, so the most common case is that
// both the segments and the item are unstable behind the same feature flag.
//
// We check here rather than in `visit_path_segment` to prevent visiting the last
// path segment twice
//
// We include special cases via #[rustc_allowed_through_unstable_modules] for items
// that were accidentally stabilized through unstable paths before this check was
// added, such as `core::intrinsics::transmute`
let parents = path.segments.iter().rev().skip(1);
for path_segment in parents {
if let Some(def_id) = path_segment.res.opt_def_id() {
match is_allowed_through_unstable_modules {
None => {
// Emit a hard stability error if this path is not stable.
// use `None` for id to prevent deprecation check
self.tcx.check_stability_allow_unstable(
def_id,
None,
path.span,
None,
if is_unstable_reexport(self.tcx, id) {
AllowUnstable::Yes
} else {
AllowUnstable::No
},
);
}
Some(deprecation) => {
// Call the stability check directly so that we can control which
// diagnostic is emitted.
let eval_result = self.tcx.eval_stability_allow_unstable(
def_id,
None,
path.span,
None,
if is_unstable_reexport(self.tcx, id) {
AllowUnstable::Yes
} else {
AllowUnstable::No
},
);
let is_allowed = matches!(eval_result, EvalResult::Allow);
if !is_allowed {
// Calculating message for lint involves calling `self.def_path_str`,
// which will by default invoke the expensive `visible_parent_map` query.
// Skip all that work if the lint is allowed anyway.
if self.tcx.lint_level_at_node(DEPRECATED, id).0
== lint::Level::Allow
{
return;
}
// Show a deprecation message.
let def_path =
with_no_trimmed_paths!(self.tcx.def_path_str(def_id));
let def_kind = self.tcx.def_descr(def_id);
let diag = Deprecated {
sub: None,
kind: def_kind.to_owned(),
path: def_path,
note: Some(deprecation),
since_kind: lint::DeprecatedSinceKind::InEffect,
};
self.tcx.emit_node_span_lint(
DEPRECATED,
id,
method_span.unwrap_or(path.span),
diag,
);
}
}
}
}
}