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Rollup merge of #119963 - clubby789:spec-allow-internal-unstable, r=compiler-errors

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Fix `allow_internal_unstable` for `(min_)specialization`

Fixes #119950

Blocked on #119949 (comment doesn't make sense until that merges)

I'd like to follow this up and look for more instances of not properly checking spans for features but I wanted to fix the motivating issue.
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Matthias Krüger 2024-01-15 08:44:49 +01:00 • committed by GitHub
commit 0891cb4d81
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3 changed files with 44 additions and 3 deletions
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26
compiler/rustc_trait_selection/src/traits/specialize/mod.rs
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@ -26,7 +26,7 @@ use rustc_middle::ty::{self, ImplSubject, Ty, TyCtxt, TypeVisitableExt};
use rustc_middle::ty::{GenericArgs, GenericArgsRef};
use rustc_session::lint::builtin::COHERENCE_LEAK_CHECK;
use rustc_session::lint::builtin::ORDER_DEPENDENT_TRAIT_OBJECTS;
use rustc_span::{ErrorGuaranteed, Span, DUMMY_SP};
use rustc_span::{sym, ErrorGuaranteed, Span, DUMMY_SP};
use super::util;
use super::SelectionContext;
@ -142,10 +142,30 @@ pub fn translate_args_with_cause<'tcx>(
pub(super) fn specializes(tcx: TyCtxt<'_>, (impl1_def_id, impl2_def_id): (DefId, DefId)) -> bool {
// The feature gate should prevent introducing new specializations, but not
// taking advantage of upstream ones.
// If specialization is enabled for this crate then no extra checks are needed.
// If it's not, and either of the `impl`s is local to this crate, then this definitely
// isn't specializing - unless specialization is enabled for the `impl` span,
// e.g. if it comes from an `allow_internal_unstable` macro
let features = tcx.features();
let specialization_enabled = features.specialization || features.min_specialization;
if !specialization_enabled && (impl1_def_id.is_local() || impl2_def_id.is_local()) {
return false;
if !specialization_enabled {
if impl1_def_id.is_local() {
let span = tcx.def_span(impl1_def_id);
if !span.allows_unstable(sym::specialization)
&& !span.allows_unstable(sym::min_specialization)
{
return false;
}
}
if impl2_def_id.is_local() {
let span = tcx.def_span(impl2_def_id);
if !span.allows_unstable(sym::specialization)
&& !span.allows_unstable(sym::min_specialization)
{
return false;
}
}
}
// We determine whether there's a subset relationship by: