Store impl unsafety in impl trait header

Author: oli-obk

compiler/rustc_hir_analysis/src/coherence/mod.rs

@@ -132,12 +132,12 @@ fn coherent_trait(tcx: TyCtxt<'_>, def_id: DefId) -> Result<(), ErrorGuaranteed>
     let mut res = tcx.ensure().specialization_graph_of(def_id);
 
     for &impl_def_id in impls {
-        let trait_ref = tcx.impl_trait_ref(impl_def_id).unwrap().instantiate_identity();
+        let trait_header = tcx.impl_trait_header(impl_def_id).unwrap().instantiate_identity();
 
-        res = res.and(check_impl(tcx, impl_def_id, trait_ref));
-        res = res.and(check_object_overlap(tcx, impl_def_id, trait_ref));
+        res = res.and(check_impl(tcx, impl_def_id, trait_header.trait_ref));
+        res = res.and(check_object_overlap(tcx, impl_def_id, trait_header.trait_ref));
 
-        res = res.and(unsafety::check_item(tcx, impl_def_id, trait_ref));
+        res = res.and(unsafety::check_item(tcx, impl_def_id, trait_header));
         res = res.and(tcx.ensure().orphan_check_impl(impl_def_id));
         res = res.and(builtin::check_trait(tcx, def_id, impl_def_id));
     }

compiler/rustc_hir_analysis/src/coherence/unsafety.rs

@@ -2,23 +2,23 @@
 //! crate or pertains to a type defined in this crate.
 
 use rustc_errors::{codes::*, struct_span_code_err};
-use rustc_hir as hir;
 use rustc_hir::Unsafety;
-use rustc_middle::ty::{TraitRef, TyCtxt};
+use rustc_middle::ty::{ImplPolarity::*, ImplTraitHeader, TyCtxt};
 use rustc_span::def_id::LocalDefId;
 use rustc_span::ErrorGuaranteed;
 
 pub(super) fn check_item(
     tcx: TyCtxt<'_>,
     def_id: LocalDefId,
-    trait_ref: TraitRef<'_>,
+    trait_header: ImplTraitHeader<'_>,
 ) -> Result<(), ErrorGuaranteed> {
-    let item = tcx.hir().expect_item(def_id);
-    let impl_ = item.expect_impl();
+    let trait_ref = trait_header.trait_ref;
     let trait_def = tcx.trait_def(trait_ref.def_id);
-    let unsafe_attr = impl_.generics.params.iter().find(|p| p.pure_wrt_drop).map(|_| "may_dangle");
-    match (trait_def.unsafety, unsafe_attr, impl_.unsafety, impl_.polarity) {
-        (Unsafety::Normal, None, Unsafety::Unsafe, hir::ImplPolarity::Positive) => {
+    let unsafe_attr =
+        tcx.generics_of(def_id).params.iter().find(|p| p.pure_wrt_drop).map(|_| "may_dangle");
+    match (trait_def.unsafety, unsafe_attr, trait_header.unsafety, trait_header.polarity) {
+        (Unsafety::Normal, None, Unsafety::Unsafe, Positive | Reservation) => {
+            let span = tcx.def_span(def_id);
             return Err(struct_span_code_err!(
                 tcx.dcx(),
                 tcx.def_span(def_id),
@@ -27,18 +27,19 @@ pub(super) fn check_item(
                 trait_ref.print_trait_sugared()
             )
             .with_span_suggestion_verbose(
-                item.span.with_hi(item.span.lo() + rustc_span::BytePos(7)),
+                span.with_hi(span.lo() + rustc_span::BytePos(7)),
                 "remove `unsafe` from this trait implementation",
                 "",
                 rustc_errors::Applicability::MachineApplicable,
             )
             .emit());
         }
 
-        (Unsafety::Unsafe, _, Unsafety::Normal, hir::ImplPolarity::Positive) => {
+        (Unsafety::Unsafe, _, Unsafety::Normal, Positive | Reservation) => {
+            let span = tcx.def_span(def_id);
             return Err(struct_span_code_err!(
                 tcx.dcx(),
-                tcx.def_span(def_id),
+                span,
                 E0200,
                 "the trait `{}` requires an `unsafe impl` declaration",
                 trait_ref.print_trait_sugared()
@@ -50,18 +51,19 @@ pub(super) fn check_item(
                 trait_ref.print_trait_sugared()
             ))
             .with_span_suggestion_verbose(
-                item.span.shrink_to_lo(),
+                span.shrink_to_lo(),
                 "add `unsafe` to this trait implementation",
                 "unsafe ",
                 rustc_errors::Applicability::MaybeIncorrect,
             )
             .emit());
         }
 
-        (Unsafety::Normal, Some(attr_name), Unsafety::Normal, hir::ImplPolarity::Positive) => {
+        (Unsafety::Normal, Some(attr_name), Unsafety::Normal, Positive | Reservation) => {
+            let span = tcx.def_span(def_id);
             return Err(struct_span_code_err!(
                 tcx.dcx(),
-                tcx.def_span(def_id),
+                span,
                 E0569,
                 "requires an `unsafe impl` declaration due to `#[{}]` attribute",
                 attr_name
@@ -73,22 +75,22 @@ pub(super) fn check_item(
                 trait_ref.print_trait_sugared()
             ))
             .with_span_suggestion_verbose(
-                item.span.shrink_to_lo(),
+                span.shrink_to_lo(),
                 "add `unsafe` to this trait implementation",
                 "unsafe ",
                 rustc_errors::Applicability::MaybeIncorrect,
             )
             .emit());
         }
 
-        (_, _, Unsafety::Unsafe, hir::ImplPolarity::Negative(_)) => {
+        (_, _, Unsafety::Unsafe, Negative) => {
             // Reported in AST validation
-            tcx.dcx().span_delayed_bug(item.span, "unsafe negative impl");
+            tcx.dcx().span_delayed_bug(tcx.def_span(def_id), "unsafe negative impl");
             Ok(())
         }
-        (_, _, Unsafety::Normal, hir::ImplPolarity::Negative(_))
-        | (Unsafety::Unsafe, _, Unsafety::Unsafe, hir::ImplPolarity::Positive)
-        | (Unsafety::Normal, Some(_), Unsafety::Unsafe, hir::ImplPolarity::Positive)
+        (_, _, Unsafety::Normal, Negative)
+        | (Unsafety::Unsafe, _, Unsafety::Unsafe, Positive | Reservation)
+        | (Unsafety::Normal, Some(_), Unsafety::Unsafe, Positive | Reservation)
         | (Unsafety::Normal, None, Unsafety::Normal, _) => Ok(()),
     }
 }

compiler/rustc_hir_analysis/src/collect.rs

@@ -1539,6 +1539,7 @@ fn impl_trait_header(
             };
             ty::EarlyBinder::bind(ty::ImplTraitHeader {
                 trait_ref,
+                unsafety: impl_.unsafety,
                 polarity: polarity_of_impl(tcx, def_id,  impl_, item.span)
             })
         })

compiler/rustc_middle/src/ty/mod.rs

@@ -252,6 +252,7 @@ pub struct ImplHeader<'tcx> {
 pub struct ImplTraitHeader<'tcx> {
     pub trait_ref: ty::TraitRef<'tcx>,
     pub polarity: ImplPolarity,
+    pub unsafety: hir::Unsafety,
 }
 
 #[derive(Copy, Clone, PartialEq, Eq, Debug, TypeFoldable, TypeVisitable)]