Add documentation

compiler/rustc_middle/src/middle/stability.rs

@@ -395,7 +395,7 @@ impl<'tcx> TyCtxt<'tcx> {
     /// This function will also check if the item is deprecated.
     /// If so, and `id` is not `None`, a deprecated lint attached to `id` will be emitted.
     pub fn check_stability(self, def_id: DefId, id: Option<HirId>, span: Span) {
-        self.check_stability_internal(def_id, id, span, |span, def_id| {
+        self.check_optional_stability(def_id, id, span, |span, def_id| {
             // The API could be uncallable for other reasons, for example when a private module
             // was referenced.
             self.sess.delay_span_bug(span, &format!("encountered unmarked API: {:?}", def_id));
@@ -409,7 +409,10 @@ impl<'tcx> TyCtxt<'tcx> {
     ///
     /// This function will also check if the item is deprecated.
     /// If so, and `id` is not `None`, a deprecated lint attached to `id` will be emitted.
-    pub fn check_stability_internal(
+    ///
+    /// The `unmarked` closure is called definitions without a stability annotation.
+    /// This is needed for generic parameters, since they may not be marked when used in a staged_api crate.
+    pub fn check_optional_stability(
         self,
         def_id: DefId,
         id: Option<HirId>,

compiler/rustc_passes/src/stability.rs

@@ -37,6 +37,20 @@ enum AnnotationKind {
     Container,
 }
 
+/// Inheriting deprecations Nested items causes duplicate warnings.
+/// Inheriting the deprecation of `Foo<T>` onto the parameter `T`, would cause a duplicate warnings.
+#[derive(PartialEq, Copy, Clone)]
+enum InheritDeprecation {
+    Yes,
+    No,
+}
+
+impl InheritDeprecation {
+    fn yes(&self) -> bool {
+        *self == InheritDeprecation::Yes
+    }
+}
+
 // A private tree-walker for producing an Index.
 struct Annotator<'a, 'tcx> {
     tcx: TyCtxt<'tcx>,
@@ -56,7 +70,7 @@ impl<'a, 'tcx> Annotator<'a, 'tcx> {
         attrs: &[Attribute],
         item_sp: Span,
         kind: AnnotationKind,
-        inherit_deprecation: bool,
+        inherit_deprecation: InheritDeprecation,
         visit_children: F,
     ) where
         F: FnOnce(&mut Self),
@@ -81,7 +95,7 @@ impl<'a, 'tcx> Annotator<'a, 'tcx> {
             let depr_entry = DeprecationEntry::local(depr.clone(), hir_id);
             self.index.depr_map.insert(hir_id, depr_entry);
         } else if let Some(parent_depr) = self.parent_depr.clone() {
-            if inherit_deprecation {
+            if inherit_deprecation.yes() {
                 is_deprecated = true;
                 info!("tagging child {:?} as deprecated from parent", hir_id);
                 self.index.depr_map.insert(hir_id, parent_depr);
@@ -189,7 +203,7 @@ 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 && stab.level.is_unstable() {
+                if inherit_deprecation.yes() && stab.level.is_unstable() {
                     self.index.stab_map.insert(hir_id, stab);
                 }
             }
@@ -240,7 +254,7 @@ impl<'a, 'tcx> Annotator<'a, 'tcx> {
     }
 
     // returns true if an error occurred, used to suppress some spurious errors
-    fn forbid_staged_api_attrs(&mut self, hir_id: HirId, attrs: &[Attribute], inherit_deprecation: bool) -> bool {
+    fn forbid_staged_api_attrs(&mut self, hir_id: HirId, attrs: &[Attribute], inherit_deprecation: InheritDeprecation) -> bool {
         // Emit errors for non-staged-api crates.
         let unstable_attrs = [
             sym::unstable,
@@ -268,7 +282,7 @@ 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 && stab.level.is_unstable() {
+            if inherit_deprecation.yes() && stab.level.is_unstable() {
                 self.index.stab_map.insert(hir_id, stab);
             }
         }
@@ -309,7 +323,7 @@ impl<'a, 'tcx> Visitor<'tcx> for Annotator<'a, 'tcx> {
                         &i.attrs,
                         i.span,
                         AnnotationKind::Required,
-                        true,
+                        InheritDeprecation::Yes,
                         |_| {},
                     )
                 }
@@ -317,55 +331,92 @@ impl<'a, 'tcx> Visitor<'tcx> for Annotator<'a, 'tcx> {
             _ => {}
         }
 
-        self.annotate(i.hir_id, &i.attrs, i.span, kind, true, |v| intravisit::walk_item(v, i));
+        self.annotate(i.hir_id, &i.attrs, i.span, kind, InheritDeprecation::Yes, |v| {
+            intravisit::walk_item(v, i)
+        });
         self.in_trait_impl = orig_in_trait_impl;
     }
 
     fn visit_trait_item(&mut self, ti: &'tcx hir::TraitItem<'tcx>) {
-        self.annotate(ti.hir_id, &ti.attrs, ti.span, AnnotationKind::Required, true, |v| {
+        self.annotate(
+            ti.hir_id,
+            &ti.attrs,
+            ti.span,
+            AnnotationKind::Required,
+            InheritDeprecation::Yes,
+            |v| {
                 intravisit::walk_trait_item(v, ti);
-        });
+            },
+        );
     }
 
     fn visit_impl_item(&mut self, ii: &'tcx hir::ImplItem<'tcx>) {
         let kind =
             if self.in_trait_impl { AnnotationKind::Prohibited } else { AnnotationKind::Required };
-        self.annotate(ii.hir_id, &ii.attrs, ii.span, kind, true, |v| {
+        self.annotate(ii.hir_id, &ii.attrs, ii.span, kind, InheritDeprecation::Yes, |v| {
             intravisit::walk_impl_item(v, ii);
         });
     }
 
     fn visit_variant(&mut self, var: &'tcx Variant<'tcx>, g: &'tcx Generics<'tcx>, item_id: HirId) {
-        self.annotate(var.id, &var.attrs, var.span, AnnotationKind::Required, true, |v| {
+        self.annotate(
+            var.id,
+            &var.attrs,
+            var.span,
+            AnnotationKind::Required,
+            InheritDeprecation::Yes,
+            |v| {
                 if let Some(ctor_hir_id) = var.data.ctor_hir_id() {
                     v.annotate(
                         ctor_hir_id,
                         &var.attrs,
                         var.span,
                         AnnotationKind::Required,
-                    true,
+                        InheritDeprecation::Yes,
                         |_| {},
                     );
                 }
 
                 intravisit::walk_variant(v, var, g, item_id)
-        })
+            },
+        )
     }
 
     fn visit_struct_field(&mut self, s: &'tcx StructField<'tcx>) {
-        self.annotate(s.hir_id, &s.attrs, s.span, AnnotationKind::Required, true, |v| {
+        self.annotate(
+            s.hir_id,
+            &s.attrs,
+            s.span,
+            AnnotationKind::Required,
+            InheritDeprecation::Yes,
+            |v| {
                 intravisit::walk_struct_field(v, s);
-        });
+            },
+        );
     }
 
     fn visit_foreign_item(&mut self, i: &'tcx hir::ForeignItem<'tcx>) {
-        self.annotate(i.hir_id, &i.attrs, i.span, AnnotationKind::Required, true, |v| {
+        self.annotate(
+            i.hir_id,
+            &i.attrs,
+            i.span,
+            AnnotationKind::Required,
+            InheritDeprecation::Yes,
+            |v| {
                 intravisit::walk_foreign_item(v, i);
-        });
+            },
+        );
     }
 
     fn visit_macro_def(&mut self, md: &'tcx hir::MacroDef<'tcx>) {
-        self.annotate(md.hir_id, &md.attrs, md.span, AnnotationKind::Required, true, |_| {});
+        self.annotate(
+            md.hir_id,
+            &md.attrs,
+            md.span,
+            AnnotationKind::Required,
+            InheritDeprecation::Yes,
+            |_| {},
+        );
     }
 
     fn visit_generic_param(&mut self, p: &'tcx hir::GenericParam<'tcx>) {
@@ -377,7 +428,7 @@ impl<'a, 'tcx> Visitor<'tcx> for Annotator<'a, 'tcx> {
             _ => AnnotationKind::Prohibited,
         };
 
-        self.annotate(p.hir_id, &p.attrs, p.span, kind, false, |v| {
+        self.annotate(p.hir_id, &p.attrs, p.span, kind, InheritDeprecation::No, |v| {
             intravisit::walk_generic_param(v, p);
         });
     }
@@ -519,7 +570,7 @@ fn new_index(tcx: TyCtxt<'tcx>) -> Index<'tcx> {
             &krate.item.attrs,
             krate.item.span,
             AnnotationKind::Required,
-            true,
+            InheritDeprecation::Yes,
             |v| intravisit::walk_crate(v, krate),
         );
     }

compiler/rustc_typeck/src/astconv/mod.rs

@@ -362,7 +362,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                 }
                 (GenericParamDefKind::Type { has_default, .. }, GenericArg::Type(ty)) => {
                     if *has_default {
-                        tcx.check_stability_internal(
+                        tcx.check_optional_stability(
                             param.def_id,
                             Some(arg.id()),
                             arg.span(),