rustc: use DefKind instead of Def, where possible.

src/librustc/hir/def.rs

@@ -80,6 +80,53 @@ pub enum DefKind {
     Macro(MacroKind),
 }
 
+impl DefKind {
+    pub fn descr(self) -> &'static str {
+        match self {
+            DefKind::Fn => "function",
+            DefKind::Mod => "module",
+            DefKind::Static => "static",
+            DefKind::Enum => "enum",
+            DefKind::Variant => "variant",
+            DefKind::Ctor(CtorOf::Variant, CtorKind::Fn) => "tuple variant",
+            DefKind::Ctor(CtorOf::Variant, CtorKind::Const) => "unit variant",
+            DefKind::Ctor(CtorOf::Variant, CtorKind::Fictive) => "struct variant",
+            DefKind::Struct => "struct",
+            DefKind::Ctor(CtorOf::Struct, CtorKind::Fn) => "tuple struct",
+            DefKind::Ctor(CtorOf::Struct, CtorKind::Const) => "unit struct",
+            DefKind::Ctor(CtorOf::Struct, CtorKind::Fictive) =>
+                bug!("impossible struct constructor"),
+            DefKind::Existential => "existential type",
+            DefKind::TyAlias => "type alias",
+            DefKind::TraitAlias => "trait alias",
+            DefKind::AssociatedTy => "associated type",
+            DefKind::AssociatedExistential => "associated existential type",
+            DefKind::Union => "union",
+            DefKind::Trait => "trait",
+            DefKind::ForeignTy => "foreign type",
+            DefKind::Method => "method",
+            DefKind::Const => "constant",
+            DefKind::AssociatedConst => "associated constant",
+            DefKind::TyParam => "type parameter",
+            DefKind::ConstParam => "const parameter",
+            DefKind::Macro(macro_kind) => macro_kind.descr(),
+        }
+    }
+
+    /// An English article for the def.
+    pub fn article(&self) -> &'static str {
+        match *self {
+            DefKind::AssociatedTy
+            | DefKind::AssociatedConst
+            | DefKind::AssociatedExistential
+            | DefKind::Enum
+            | DefKind::Existential => "an",
+            DefKind::Macro(macro_kind) => macro_kind.article(),
+            _ => "a",
+        }
+    }
+}
+
 #[derive(Clone, Copy, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, HashStable)]
 pub enum Def<Id = hir::HirId> {
     Def(DefKind, DefId),
@@ -328,39 +375,13 @@ impl<Id> Def<Id> {
     /// A human readable name for the def kind ("function", "module", etc.).
     pub fn kind_name(&self) -> &'static str {
         match *self {
-            Def::Def(DefKind::Fn, _) => "function",
-            Def::Def(DefKind::Mod, _) => "module",
-            Def::Def(DefKind::Static, _) => "static",
-            Def::Def(DefKind::Enum, _) => "enum",
-            Def::Def(DefKind::Variant, _) => "variant",
-            Def::Def(DefKind::Ctor(CtorOf::Variant, CtorKind::Fn), _) => "tuple variant",
-            Def::Def(DefKind::Ctor(CtorOf::Variant, CtorKind::Const), _) => "unit variant",
-            Def::Def(DefKind::Ctor(CtorOf::Variant, CtorKind::Fictive), _) => "struct variant",
-            Def::Def(DefKind::Struct, _) => "struct",
-            Def::Def(DefKind::Ctor(CtorOf::Struct, CtorKind::Fn), _) => "tuple struct",
-            Def::Def(DefKind::Ctor(CtorOf::Struct, CtorKind::Const), _) => "unit struct",
-            Def::Def(DefKind::Ctor(CtorOf::Struct, CtorKind::Fictive), _) =>
-                bug!("impossible struct constructor"),
-            Def::Def(DefKind::Existential, _) => "existential type",
-            Def::Def(DefKind::TyAlias, _) => "type alias",
-            Def::Def(DefKind::TraitAlias, _) => "trait alias",
-            Def::Def(DefKind::AssociatedTy, _) => "associated type",
-            Def::Def(DefKind::AssociatedExistential, _) => "associated existential type",
+            Def::Def(kind, _) => kind.descr(),
             Def::SelfCtor(..) => "self constructor",
-            Def::Def(DefKind::Union, _) => "union",
-            Def::Def(DefKind::Trait, _) => "trait",
-            Def::Def(DefKind::ForeignTy, _) => "foreign type",
-            Def::Def(DefKind::Method, _) => "method",
-            Def::Def(DefKind::Const, _) => "constant",
-            Def::Def(DefKind::AssociatedConst, _) => "associated constant",
-            Def::Def(DefKind::TyParam, _) => "type parameter",
-            Def::Def(DefKind::ConstParam, _) => "const parameter",
             Def::PrimTy(..) => "builtin type",
             Def::Local(..) => "local variable",
             Def::Upvar(..) => "closure capture",
             Def::Label(..) => "label",
             Def::SelfTy(..) => "self type",
-            Def::Def(DefKind::Macro(macro_kind), _) => macro_kind.descr(),
             Def::ToolMod => "tool module",
             Def::NonMacroAttr(attr_kind) => attr_kind.descr(),
             Def::Err => "unresolved item",
@@ -370,13 +391,8 @@ impl<Id> Def<Id> {
     /// An English article for the def.
     pub fn article(&self) -> &'static str {
         match *self {
-            Def::Def(DefKind::AssociatedTy, _)
-            | Def::Def(DefKind::AssociatedConst, _)
-            | Def::Def(DefKind::AssociatedExistential, _)
-            | Def::Def(DefKind::Enum, _)
-            | Def::Def(DefKind::Existential, _)
-            | Def::Err => "an",
-            Def::Def(DefKind::Macro(macro_kind), _) => macro_kind.article(),
+            Def::Def(kind, _) => kind.article(),
+            Def::Err => "an",
             _ => "a",
         }
     }

src/librustc/hir/map/mod.rs

@@ -17,7 +17,7 @@ use syntax::ext::base::MacroKind;
 use syntax_pos::{Span, DUMMY_SP};
 
 use crate::hir::*;
-use crate::hir::{Def, DefKind};
+use crate::hir::DefKind;
 use crate::hir::itemlikevisit::ItemLikeVisitor;
 use crate::hir::print::Nested;
 use crate::util::nodemap::FxHashMap;
@@ -310,14 +310,14 @@ impl<'hir> Map<'hir> {
         self.definitions.as_local_node_id(def_id.to_def_id()).unwrap()
     }
 
-    pub fn describe_def(&self, node_id: NodeId) -> Option<Def> {
+    fn def_kind(&self, node_id: NodeId) -> Option<DefKind> {
         let node = if let Some(node) = self.find(node_id) {
             node
         } else {
             return None
         };
 
-        let kind = match node {
+        Some(match node {
             Node::Item(item) => {
                 match item.node {
                     ItemKind::Static(..) => DefKind::Static,
@@ -382,15 +382,11 @@ impl<'hir> Map<'hir> {
             Node::TraitRef(_) |
             Node::Pat(_) |
             Node::Binding(_) |
+            Node::Local(_) |
             Node::Lifetime(_) |
             Node::Visibility(_) |
             Node::Block(_) |
             Node::Crate => return None,
-            // FIXME(eddyb) this is the only non-`DefKind` case here,
-            // investigate whether it's actually used, and ideally remove it.
-            Node::Local(local) => {
-                return Some(Def::Local(local.hir_id));
-            }
             Node::MacroDef(_) => DefKind::Macro(MacroKind::Bang),
             Node::GenericParam(param) => {
                 match param.kind {
@@ -399,14 +395,7 @@ impl<'hir> Map<'hir> {
                     GenericParamKind::Const { .. } => DefKind::ConstParam,
                 }
             }
-        };
-        Some(Def::Def(kind, self.local_def_id(node_id)))
-    }
-
-    // FIXME(@ljedrz): replace the NodeId variant
-    pub fn describe_def_by_hir_id(&self, hir_id: HirId) -> Option<Def> {
-        let node_id = self.hir_to_node_id(hir_id);
-        self.describe_def(node_id)
+        })
     }
 
     fn entry_count(&self) -> usize {
@@ -1464,11 +1453,11 @@ fn hir_id_to_string(map: &Map<'_>, id: HirId, include_id: bool) -> String {
     node_id_to_string(map, node_id, include_id)
 }
 
-pub fn describe_def(tcx: TyCtxt<'_, '_, '_>, def_id: DefId) -> Option<Def> {
+pub fn def_kind(tcx: TyCtxt<'_, '_, '_>, def_id: DefId) -> Option<DefKind> {
     if let Some(node_id) = tcx.hir().as_local_node_id(def_id) {
-        tcx.hir().describe_def(node_id)
+        tcx.hir().def_kind(node_id)
     } else {
-        bug!("Calling local describe_def query provider for upstream DefId: {:?}",
+        bug!("Calling local def_kind query provider for upstream DefId: {:?}",
              def_id)
     }
 }

src/librustc/hir/mod.rs

@@ -2521,7 +2521,7 @@ pub type GlobMap = NodeMap<FxHashSet<Name>>;
 
 pub fn provide(providers: &mut Providers<'_>) {
     check_attr::provide(providers);
-    providers.describe_def = map::describe_def;
+    providers.def_kind = map::def_kind;
 }
 
 #[derive(Clone, RustcEncodable, RustcDecodable, HashStable)]

src/librustc/middle/reachable.rs

@@ -98,6 +98,7 @@ impl<'a, 'tcx> Visitor<'tcx> for ReachableContext<'a, 'tcx> {
             }
             hir::ExprKind::MethodCall(..) => {
                 self.tables.type_dependent_def(expr.hir_id)
+                    .map(|(kind, def_id)| Def::Def(kind, def_id))
             }
             _ => None
         };

src/librustc/middle/stability.rs

@@ -525,10 +525,10 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
     // See issue #38412.
     fn skip_stability_check_due_to_privacy(self, mut def_id: DefId) -> bool {
         // Check if `def_id` is a trait method.
-        match self.describe_def(def_id) {
-            Some(Def::Def(DefKind::Method, _)) |
-            Some(Def::Def(DefKind::AssociatedTy, _)) |
-            Some(Def::Def(DefKind::AssociatedConst, _)) => {
+        match self.def_kind(def_id) {
+            Some(DefKind::Method) |
+            Some(DefKind::AssociatedTy) |
+            Some(DefKind::AssociatedConst) => {
                 if let ty::TraitContainer(trait_def_id) = self.associated_item(def_id).container {
                     // Trait methods do not declare visibility (even
                     // for visibility info in cstore). Use containing

src/librustc/query/mod.rs

@@ -469,7 +469,7 @@ rustc_queries! {
             cache { true }
         }
 
-        query describe_def(_: DefId) -> Option<Def> {}
+        query def_kind(_: DefId) -> Option<DefKind> {}
         query def_span(_: DefId) -> Span {
             // FIXME(mw): DefSpans are not really inputs since they are derived from
             // HIR. But at the moment HIR hashing still contains some hacks that allow

src/librustc/ty/context.rs

@@ -44,6 +44,7 @@ use crate::ty::steal::Steal;
 use crate::ty::subst::{UserSubsts, UnpackedKind};
 use crate::ty::{BoundVar, BindingMode};
 use crate::ty::CanonicalPolyFnSig;
+use crate::util::common::ErrorReported;
 use crate::util::nodemap::{DefIdMap, DefIdSet, ItemLocalMap, ItemLocalSet};
 use crate::util::nodemap::{FxHashMap, FxHashSet};
 use errors::DiagnosticBuilder;
@@ -347,7 +348,7 @@ pub struct TypeckTables<'tcx> {
 
     /// Resolved definitions for `<T>::X` associated paths and
     /// method calls, including those of overloaded operators.
-    type_dependent_defs: ItemLocalMap<Def>,
+    type_dependent_defs: ItemLocalMap<Result<(DefKind, DefId), ErrorReported>>,
 
     /// Resolved field indices for field accesses in expressions (`S { field }`, `obj.field`)
     /// or patterns (`S { field }`). The index is often useful by itself, but to learn more
@@ -481,30 +482,32 @@ impl<'tcx> TypeckTables<'tcx> {
     pub fn qpath_def(&self, qpath: &hir::QPath, id: hir::HirId) -> Def {
         match *qpath {
             hir::QPath::Resolved(_, ref path) => path.def,
-            hir::QPath::TypeRelative(..) => {
-                validate_hir_id_for_typeck_tables(self.local_id_root, id, false);
-                self.type_dependent_defs.get(&id.local_id).cloned().unwrap_or(Def::Err)
-            }
+            hir::QPath::TypeRelative(..) => self.type_dependent_def(id)
+                .map_or(Def::Err, |(kind, def_id)| Def::Def(kind, def_id)),
         }
     }
 
-    pub fn type_dependent_defs(&self) -> LocalTableInContext<'_, Def> {
+    pub fn type_dependent_defs(
+        &self,
+    ) -> LocalTableInContext<'_, Result<(DefKind, DefId), ErrorReported>> {
         LocalTableInContext {
             local_id_root: self.local_id_root,
             data: &self.type_dependent_defs
         }
     }
 
-    pub fn type_dependent_def(&self, id: HirId) -> Option<Def> {
+    pub fn type_dependent_def(&self, id: HirId) -> Option<(DefKind, DefId)> {
         validate_hir_id_for_typeck_tables(self.local_id_root, id, false);
-        self.type_dependent_defs.get(&id.local_id).cloned()
+        self.type_dependent_defs.get(&id.local_id).cloned().and_then(|r| r.ok())
     }
 
     pub fn type_dependent_def_id(&self, id: HirId) -> Option<DefId> {
-        self.type_dependent_def(id).map(|def| def.def_id())
+        self.type_dependent_def(id).map(|(_, def_id)| def_id)
     }
 
-    pub fn type_dependent_defs_mut(&mut self) -> LocalTableInContextMut<'_, Def> {
+    pub fn type_dependent_defs_mut(
+        &mut self,
+    ) -> LocalTableInContextMut<'_, Result<(DefKind, DefId), ErrorReported>> {
         LocalTableInContextMut {
             local_id_root: self.local_id_root,
             data: &mut self.type_dependent_defs
@@ -658,7 +661,7 @@ impl<'tcx> TypeckTables<'tcx> {
         }
 
         match self.type_dependent_defs().get(expr.hir_id) {
-            Some(&Def::Def(DefKind::Method, _)) => true,
+            Some(Ok((DefKind::Method, _))) => true,
             _ => false
         }
     }

src/librustc/ty/mod.rs

@@ -191,12 +191,12 @@ pub enum AssociatedKind {
 }
 
 impl AssociatedItem {
-    pub fn def(&self) -> Def {
+    pub fn def_kind(&self) -> DefKind {
         match self.kind {
-            AssociatedKind::Const => Def::Def(DefKind::AssociatedConst, self.def_id),
-            AssociatedKind::Method => Def::Def(DefKind::Method, self.def_id),
-            AssociatedKind::Type => Def::Def(DefKind::AssociatedTy, self.def_id),
-            AssociatedKind::Existential => Def::Def(DefKind::AssociatedExistential, self.def_id),
+            AssociatedKind::Const => DefKind::AssociatedConst,
+            AssociatedKind::Method => DefKind::Method,
+            AssociatedKind::Type => DefKind::AssociatedTy,
+            AssociatedKind::Existential => DefKind::AssociatedExistential,
         }
     }
 
@@ -2805,10 +2805,10 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
                 _ => false,
             }
         } else {
-            match self.describe_def(def_id).expect("no def for def-id") {
-                Def::Def(DefKind::AssociatedConst, _)
-                | Def::Def(DefKind::Method, _)
-                | Def::Def(DefKind::AssociatedTy, _) => true,
+            match self.def_kind(def_id).expect("no def for def-id") {
+                DefKind::AssociatedConst
+                | DefKind::Method
+                | DefKind::AssociatedTy => true,
                 _ => false,
             }
         };
@@ -3046,7 +3046,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
     /// `DefId` of the impl that the method belongs to; otherwise, returns `None`.
     pub fn impl_of_method(self, def_id: DefId) -> Option<DefId> {
         let item = if def_id.krate != LOCAL_CRATE {
-            if let Some(Def::Def(DefKind::Method, _)) = self.describe_def(def_id) {
+            if let Some(DefKind::Method) = self.def_kind(def_id) {
                 Some(self.associated_item(def_id))
             } else {
                 None

src/librustc/ty/query/mod.rs

@@ -1,6 +1,6 @@
 use crate::dep_graph::{self, DepNode};
 use crate::hir::def_id::{CrateNum, DefId, DefIndex};
-use crate::hir::def::{Def, Export};
+use crate::hir::def::{DefKind, Export};
 use crate::hir::{self, TraitCandidate, ItemLocalId, CodegenFnAttrs};
 use crate::infer::canonical::{self, Canonical};
 use crate::lint;

src/librustc_lint/unused.rs

@@ -87,13 +87,14 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnusedResults {
 
         let mut fn_warned = false;
         let mut op_warned = false;
-        let maybe_def = match expr.node {
+        let maybe_def_id = match expr.node {
             hir::ExprKind::Call(ref callee, _) => {
                 match callee.node {
                     hir::ExprKind::Path(ref qpath) => {
                         let def = cx.tables.qpath_def(qpath, callee.hir_id);
                         match def {
-                            Def::Def(DefKind::Fn, _) | Def::Def(DefKind::Method, _) => Some(def),
+                            Def::Def(DefKind::Fn, def_id)
+                            | Def::Def(DefKind::Method, def_id) => Some(def_id),
                             // `Def::Local` if it was a closure, for which we
                             // do not currently support must-use linting
                             _ => None
@@ -103,12 +104,11 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnusedResults {
                 }
             },
             hir::ExprKind::MethodCall(..) => {
-                cx.tables.type_dependent_def(expr.hir_id)
+                cx.tables.type_dependent_def_id(expr.hir_id)
             },
             _ => None
         };
-        if let Some(def) = maybe_def {
-            let def_id = def.def_id();
+        if let Some(def_id) = maybe_def_id {
             fn_warned = check_must_use(cx, def_id, s.span, "return value of ", "");
         } else if type_permits_lack_of_use {
             // We don't warn about unused unit or uninhabited types.

src/librustc_metadata/cstore_impl.rs

@@ -138,7 +138,7 @@ provide! { <'tcx> tcx, def_id, other, cdata,
     is_const_fn_raw => { cdata.is_const_fn_raw(def_id.index) }
     is_foreign_item => { cdata.is_foreign_item(def_id.index) }
     static_mutability => { cdata.static_mutability(def_id.index) }
-    describe_def => { cdata.get_def(def_id.index) }
+    def_kind => { cdata.def_kind(def_id.index) }
     def_span => { cdata.get_span(def_id.index, &tcx.sess) }
     lookup_stability => {
         cdata.get_stability(def_id.index).map(|s| tcx.intern_stability(s))