Auto merge of #60525 - eddyb:namespaces-not-kinds, r=petrochenkov

rustc: collapse relevant DefPathData variants into {Type,Value,Macro,Lifetime}Ns.

`DefPathData` was meant to disambiguate within each namespace, but over the years, that purpose was overlooked, and it started to serve a double-role as a sort of `DefKind` (which #60462 properly adds).
Now, we can go back to *only* categorizing namespaces (at least for the variants with names in them).

r? @petrochenkov or @nikomatsakis cc @michaelwoerister

11 files changed, 86 insertions, 121 deletions

diff --git a/src/librustc/hir/lowering.rs b/src/librustc/hir/lowering.rs
index 8361a62c07e..0ac9429de13 100644
--- a/src/librustc/hir/lowering.rs
+++ b/src/librustc/hir/lowering.rs
@@ -952,7 +952,7 @@ impl<'a> LoweringContext<'a> {
         self.resolver.definitions().create_def_with_parent(
             parent_index,
             node_id,
-            DefPathData::LifetimeParam(str_name),
+            DefPathData::LifetimeNs(str_name),
             DefIndexAddressSpace::High,
             Mark::root(),
             span,
@@ -1749,7 +1749,7 @@ impl<'a> LoweringContext<'a> {
                     self.context.resolver.definitions().create_def_with_parent(
                         self.parent,
                         def_node_id,
-                        DefPathData::LifetimeParam(name.ident().as_interned_str()),
+                        DefPathData::LifetimeNs(name.ident().as_interned_str()),
                         DefIndexAddressSpace::High,
                         Mark::root(),
                         lifetime.span,
diff --git a/src/librustc/hir/map/def_collector.rs b/src/librustc/hir/map/def_collector.rs
index 7f1352095d9..ddef64f27e8 100644
--- a/src/librustc/hir/map/def_collector.rs
+++ b/src/librustc/hir/map/def_collector.rs
@@ -141,14 +141,13 @@ impl<'a> visit::Visitor<'a> for DefCollector<'a> {
         // information we encapsulate into, the better
         let def_data = match i.node {
             ItemKind::Impl(..) => DefPathData::Impl,
-            ItemKind::Trait(..) => DefPathData::Trait(i.ident.as_interned_str()),
-            ItemKind::TraitAlias(..) => DefPathData::TraitAlias(i.ident.as_interned_str()),
-            ItemKind::Enum(..) | ItemKind::Struct(..) | ItemKind::Union(..) |
-            ItemKind::Existential(..) | ItemKind::ExternCrate(..) | ItemKind::ForeignMod(..) |
-            ItemKind::Ty(..) => DefPathData::TypeNs(i.ident.as_interned_str()),
             ItemKind::Mod(..) if i.ident == keywords::Invalid.ident() => {
                 return visit::walk_item(self, i);
             }
+            ItemKind::Mod(..) | ItemKind::Trait(..) | ItemKind::TraitAlias(..) |
+            ItemKind::Enum(..) | ItemKind::Struct(..) | ItemKind::Union(..) |
+            ItemKind::Existential(..) | ItemKind::ExternCrate(..) | ItemKind::ForeignMod(..) |
+            ItemKind::Ty(..) => DefPathData::TypeNs(i.ident.as_interned_str()),
             ItemKind::Fn(
                 ref decl,
                 ref header,
@@ -165,10 +164,9 @@ impl<'a> visit::Visitor<'a> for DefCollector<'a> {
                     body,
                 )
             }
-            ItemKind::Mod(..) => DefPathData::Module(i.ident.as_interned_str()),
             ItemKind::Static(..) | ItemKind::Const(..) | ItemKind::Fn(..) =>
                 DefPathData::ValueNs(i.ident.as_interned_str()),
-            ItemKind::MacroDef(..) => DefPathData::MacroDef(i.ident.as_interned_str()),
+            ItemKind::MacroDef(..) => DefPathData::MacroNs(i.ident.as_interned_str()),
             ItemKind::Mac(..) => return self.visit_macro_invoc(i.id),
             ItemKind::GlobalAsm(..) => DefPathData::Misc,
             ItemKind::Use(..) => {
@@ -213,7 +211,7 @@ impl<'a> visit::Visitor<'a> for DefCollector<'a> {
 
     fn visit_variant(&mut self, v: &'a Variant, g: &'a Generics, item_id: NodeId) {
         let def = self.create_def(v.node.id,
-                                  DefPathData::EnumVariant(v.node.ident.as_interned_str()),
+                                  DefPathData::TypeNs(v.node.ident.as_interned_str()),
                                   REGULAR_SPACE,
                                   v.span);
         self.with_parent(def, |this| {
@@ -230,7 +228,7 @@ impl<'a> visit::Visitor<'a> for DefCollector<'a> {
             let name = field.ident.map(|ident| ident.name)
                 .unwrap_or_else(|| Symbol::intern(&index.to_string()));
             let def = self.create_def(field.id,
-                                      DefPathData::Field(name.as_interned_str()),
+                                      DefPathData::ValueNs(name.as_interned_str()),
                                       REGULAR_SPACE,
                                       field.span);
             self.with_parent(def, |this| this.visit_struct_field(field));
@@ -240,9 +238,9 @@ impl<'a> visit::Visitor<'a> for DefCollector<'a> {
     fn visit_generic_param(&mut self, param: &'a GenericParam) {
         let name = param.ident.as_interned_str();
         let def_path_data = match param.kind {
-            GenericParamKind::Lifetime { .. } => DefPathData::LifetimeParam(name),
-            GenericParamKind::Type { .. } => DefPathData::TypeParam(name),
-            GenericParamKind::Const { .. } => DefPathData::ConstParam(name),
+            GenericParamKind::Lifetime { .. } => DefPathData::LifetimeNs(name),
+            GenericParamKind::Type { .. } => DefPathData::TypeNs(name),
+            GenericParamKind::Const { .. } => DefPathData::ValueNs(name),
         };
         self.create_def(param.id, def_path_data, REGULAR_SPACE, param.ident.span);
 
@@ -254,7 +252,7 @@ impl<'a> visit::Visitor<'a> for DefCollector<'a> {
             TraitItemKind::Method(..) | TraitItemKind::Const(..) =>
                 DefPathData::ValueNs(ti.ident.as_interned_str()),
             TraitItemKind::Type(..) => {
-                DefPathData::AssocTypeInTrait(ti.ident.as_interned_str())
+                DefPathData::TypeNs(ti.ident.as_interned_str())
             },
             TraitItemKind::Macro(..) => return self.visit_macro_invoc(ti.id),
         };
@@ -281,9 +279,9 @@ impl<'a> visit::Visitor<'a> for DefCollector<'a> {
             }
             ImplItemKind::Method(..) | ImplItemKind::Const(..) =>
                 DefPathData::ValueNs(ii.ident.as_interned_str()),
-            ImplItemKind::Type(..) => DefPathData::AssocTypeInImpl(ii.ident.as_interned_str()),
+            ImplItemKind::Type(..) |
             ImplItemKind::Existential(..) => {
-                DefPathData::AssocExistentialInImpl(ii.ident.as_interned_str())
+                DefPathData::TypeNs(ii.ident.as_interned_str())
             },
             ImplItemKind::Macro(..) => return self.visit_macro_invoc(ii.id),
         };
diff --git a/src/librustc/hir/map/definitions.rs b/src/librustc/hir/map/definitions.rs
index 1006d813e65..fc9d6d86500 100644
--- a/src/librustc/hir/map/definitions.rs
+++ b/src/librustc/hir/map/definitions.rs
@@ -337,35 +337,17 @@ pub enum DefPathData {
     // Different kinds of items and item-like things:
     /// An impl
     Impl,
-    /// A trait
-    Trait(InternedString),
-    /// An associated type **declaration** (i.e., in a trait)
-    AssocTypeInTrait(InternedString),
-    /// An associated type **value** (i.e., in an impl)
-    AssocTypeInImpl(InternedString),
-    /// An existential associated type **value** (i.e., in an impl)
-    AssocExistentialInImpl(InternedString),
     /// Something in the type NS
     TypeNs(InternedString),
     /// Something in the value NS
     ValueNs(InternedString),
-    /// A module declaration
-    Module(InternedString),
-    /// A macro rule
-    MacroDef(InternedString),
+    /// Something in the macro NS
+    MacroNs(InternedString),
+    /// Something in the lifetime NS
+    LifetimeNs(InternedString),
     /// A closure expression
     ClosureExpr,
     // Subportions of items
-    /// A type (generic) parameter
-    TypeParam(InternedString),
-    /// A lifetime (generic) parameter
-    LifetimeParam(InternedString),
-    /// A const (generic) parameter
-    ConstParam(InternedString),
-    /// A variant of a enum
-    EnumVariant(InternedString),
-    /// A struct field
-    Field(InternedString),
     /// Implicit ctor for a unit or tuple-like struct or enum variant.
     Ctor,
     /// A constant expression (see {ast,hir}::AnonConst).
@@ -376,8 +358,6 @@ pub enum DefPathData {
     /// a whole crate (as opposed to just one item). GlobalMetaData components
     /// are only supposed to show up right below the crate root.
     GlobalMetaData(InternedString),
-    /// A trait alias.
-    TraitAlias(InternedString),
 }
 
 #[derive(Copy, Clone, Hash, PartialEq, Eq, PartialOrd, Ord, Debug,
@@ -633,19 +613,9 @@ impl DefPathData {
         use self::DefPathData::*;
         match *self {
             TypeNs(name) |
-            Trait(name) |
-            TraitAlias(name) |
-            AssocTypeInTrait(name) |
-            AssocTypeInImpl(name) |
-            AssocExistentialInImpl(name) |
             ValueNs(name) |
-            Module(name) |
-            MacroDef(name) |
-            TypeParam(name) |
-            LifetimeParam(name) |
-            ConstParam(name) |
-            EnumVariant(name) |
-            Field(name) |
+            MacroNs(name) |
+            LifetimeNs(name) |
             GlobalMetaData(name) => Some(name),
 
             Impl |
@@ -662,19 +632,9 @@ impl DefPathData {
         use self::DefPathData::*;
         let s = match *self {
             TypeNs(name) |
-            Trait(name) |
-            TraitAlias(name) |
-            AssocTypeInTrait(name) |
-            AssocTypeInImpl(name) |
-            AssocExistentialInImpl(name) |
             ValueNs(name) |
-            Module(name) |
-            MacroDef(name) |
-            TypeParam(name) |
-            LifetimeParam(name) |
-            ConstParam(name) |
-            EnumVariant(name) |
-            Field(name) |
+            MacroNs(name) |
+            LifetimeNs(name) |
             GlobalMetaData(name) => {
                 return name
             }
diff --git a/src/librustc/ty/print/pretty.rs b/src/librustc/ty/print/pretty.rs
index d10da495ee7..e09dcd16bd3 100644
--- a/src/librustc/ty/print/pretty.rs
+++ b/src/librustc/ty/print/pretty.rs
@@ -355,7 +355,6 @@ pub trait PrettyPrinter<'gcx: 'tcx, 'tcx>:
             // the children of the visible parent (as was done when computing
             // `visible_parent_map`), looking for the specific child we currently have and then
             // have access to the re-exported name.
-            DefPathData::Module(ref mut name) |
             DefPathData::TypeNs(ref mut name) if Some(visible_parent) != actual_parent => {
                 let reexport = self.tcx().item_children(visible_parent)
                     .iter()
@@ -367,7 +366,7 @@ pub trait PrettyPrinter<'gcx: 'tcx, 'tcx>:
             }
             // Re-exported `extern crate` (#43189).
             DefPathData::CrateRoot => {
-                data = DefPathData::Module(
+                data = DefPathData::TypeNs(
                     self.tcx().original_crate_name(def_id.krate).as_interned_str(),
                 );
             }
@@ -859,15 +858,16 @@ impl TyCtxt<'_, '_, '_> {
     // (but also some things just print a `DefId` generally so maybe we need this?)
     fn guess_def_namespace(self, def_id: DefId) -> Namespace {
         match self.def_key(def_id).disambiguated_data.data {
-            DefPathData::ValueNs(..) |
-            DefPathData::EnumVariant(..) |
-            DefPathData::Field(..) |
-            DefPathData::AnonConst |
-            DefPathData::ConstParam(..) |
-            DefPathData::ClosureExpr |
-            DefPathData::Ctor => Namespace::ValueNS,
-
-            DefPathData::MacroDef(..) => Namespace::MacroNS,
+            DefPathData::TypeNs(..)
+            | DefPathData::CrateRoot
+            | DefPathData::ImplTrait => Namespace::TypeNS,
+
+            DefPathData::ValueNs(..)
+            | DefPathData::AnonConst
+            | DefPathData::ClosureExpr
+            | DefPathData::Ctor => Namespace::ValueNS,
+
+            DefPathData::MacroNs(..) => Namespace::MacroNS,
 
             _ => Namespace::TypeNS,
         }
diff --git a/src/librustc/ty/util.rs b/src/librustc/ty/util.rs
index 0cd1700dd0d..4c8ed71a57c 100644
--- a/src/librustc/ty/util.rs
+++ b/src/librustc/ty/util.rs
@@ -1,6 +1,7 @@
 //! Miscellaneous type-system utilities that are too small to deserve their own modules.
 
 use crate::hir;
+use crate::hir::def::DefKind;
 use crate::hir::def_id::DefId;
 use crate::hir::map::DefPathData;
 use crate::mir::interpret::{sign_extend, truncate};
@@ -529,21 +530,13 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
 
     /// Returns `true` if `def_id` refers to a trait (i.e., `trait Foo { ... }`).
     pub fn is_trait(self, def_id: DefId) -> bool {
-        if let DefPathData::Trait(_) = self.def_key(def_id).disambiguated_data.data {
-            true
-        } else {
-            false
-        }
+        self.def_kind(def_id) == Some(DefKind::Trait)
     }
 
     /// Returns `true` if `def_id` refers to a trait alias (i.e., `trait Foo = ...;`),
     /// and `false` otherwise.
     pub fn is_trait_alias(self, def_id: DefId) -> bool {
-        if let DefPathData::TraitAlias(_) = self.def_key(def_id).disambiguated_data.data {
-            true
-        } else {
-            false
-        }
+        self.def_kind(def_id) == Some(DefKind::TraitAlias)
     }
 
     /// Returns `true` if this `DefId` refers to the implicit constructor for
diff --git a/src/librustc_metadata/decoder.rs b/src/librustc_metadata/decoder.rs
index ad28f47ba04..048acf56ea7 100644
--- a/src/librustc_metadata/decoder.rs
+++ b/src/librustc_metadata/decoder.rs
@@ -459,7 +459,7 @@ crate fn proc_macro_def_path_table(crate_root: &CrateRoot,
         let def_index = definitions.create_def_with_parent(
             crate_root,
             ast::DUMMY_NODE_ID,
-            DefPathData::MacroDef(name.as_interned_str()),
+            DefPathData::MacroNs(name.as_interned_str()),
             DefIndexAddressSpace::High,
             Mark::root(),
             DUMMY_SP);
diff --git a/src/librustc_metadata/encoder.rs b/src/librustc_metadata/encoder.rs
index f914184b34f..0946dad5320 100644
--- a/src/librustc_metadata/encoder.rs
+++ b/src/librustc_metadata/encoder.rs
@@ -586,8 +586,13 @@ impl<'a, 'b: 'a, 'tcx: 'b> IsolatedEncoder<'a, 'b, 'tcx> {
         let data = VariantData {
             ctor_kind: variant.ctor_kind,
             discr: variant.discr,
+            // FIXME(eddyb) deduplicate these with `encode_enum_variant_ctor`.
             ctor: variant.ctor_def_id.map(|did| did.index),
-            ctor_sig: None,
+            ctor_sig: if variant.ctor_kind == CtorKind::Fn {
+                variant.ctor_def_id.map(|ctor_def_id| self.lazy(&tcx.fn_sig(ctor_def_id)))
+            } else {
+                None
+            },
         };
 
         let enum_id = tcx.hir().as_local_hir_id(enum_did).unwrap();
diff --git a/src/librustc_mir/monomorphize/partitioning.rs b/src/librustc_mir/monomorphize/partitioning.rs
index 368bcc33399..f321e05d681 100644
--- a/src/librustc_mir/monomorphize/partitioning.rs
+++ b/src/librustc_mir/monomorphize/partitioning.rs
@@ -99,11 +99,11 @@ use std::sync::Arc;
 use syntax::symbol::InternedString;
 use rustc::dep_graph::{WorkProductId, WorkProduct, DepNode, DepConstructor};
 use rustc::hir::{CodegenFnAttrFlags, HirId};
+use rustc::hir::def::DefKind;
 use rustc::hir::def_id::{CrateNum, DefId, LOCAL_CRATE, CRATE_DEF_INDEX};
-use rustc::hir::map::DefPathData;
 use rustc::mir::mono::{Linkage, Visibility, CodegenUnitNameBuilder};
 use rustc::middle::exported_symbols::SymbolExportLevel;
-use rustc::ty::{self, TyCtxt, InstanceDef};
+use rustc::ty::{self, DefIdTree, TyCtxt, InstanceDef};
 use rustc::ty::print::characteristic_def_id_of_type;
 use rustc::ty::query::Providers;
 use rustc::util::common::time;
@@ -805,33 +805,27 @@ fn compute_codegen_unit_name(tcx: TyCtxt<'_, '_, '_>,
     let mut cgu_def_id = None;
     // Walk backwards from the item we want to find the module for:
     loop {
-        let def_key = tcx.def_key(current_def_id);
-
-        match def_key.disambiguated_data.data {
-            DefPathData::Module(..) => {
-                if cgu_def_id.is_none() {
-                    cgu_def_id = Some(current_def_id);
-                }
+        if current_def_id.index == CRATE_DEF_INDEX {
+            if cgu_def_id.is_none() {
+                // If we have not found a module yet, take the crate root.
+                cgu_def_id = Some(DefId {
+                    krate: def_id.krate,
+                    index: CRATE_DEF_INDEX,
+                });
             }
-            DefPathData::CrateRoot { .. } => {
-                if cgu_def_id.is_none() {
-                    // If we have not found a module yet, take the crate root.
-                    cgu_def_id = Some(DefId {
-                        krate: def_id.krate,
-                        index: CRATE_DEF_INDEX,
-                    });
-                }
-                break
-            }
-            _ => {
-                // If we encounter something that is not a module, throw away
-                // any module that we've found so far because we now know that
-                // it is nested within something else.
-                cgu_def_id = None;
+            break
+        } else if tcx.def_kind(current_def_id) == Some(DefKind::Mod) {
+            if cgu_def_id.is_none() {
+                cgu_def_id = Some(current_def_id);
             }
+        } else {
+            // If we encounter something that is not a module, throw away
+            // any module that we've found so far because we now know that
+            // it is nested within something else.
+            cgu_def_id = None;
         }
 
-        current_def_id.index = def_key.parent.unwrap();
+        current_def_id = tcx.parent(current_def_id).unwrap();
     }
 
     let cgu_def_id = cgu_def_id.unwrap();
diff --git a/src/librustc_traits/lowering/mod.rs b/src/librustc_traits/lowering/mod.rs
index c3cbdb03762..50c21302632 100644
--- a/src/librustc_traits/lowering/mod.rs
+++ b/src/librustc_traits/lowering/mod.rs
@@ -1,5 +1,6 @@
 mod environment;
 
+use rustc::hir::def::DefKind;
 use rustc::hir::def_id::DefId;
 use rustc::hir::intravisit::{self, NestedVisitorMap, Visitor};
 use rustc::hir::map::definitions::DefPathData;
@@ -157,13 +158,27 @@ crate fn program_clauses_for<'a, 'tcx>(
     tcx: TyCtxt<'a, 'tcx, 'tcx>,
     def_id: DefId,
 ) -> Clauses<'tcx> {
+    // FIXME(eddyb) this should only be using `def_kind`.
     match tcx.def_key(def_id).disambiguated_data.data {
-        DefPathData::Trait(_) |
-        DefPathData::TraitAlias(_) => program_clauses_for_trait(tcx, def_id),
+        DefPathData::TypeNs(..) => match tcx.def_kind(def_id) {
+            Some(DefKind::Trait)
+            | Some(DefKind::TraitAlias) => program_clauses_for_trait(tcx, def_id),
+            // FIXME(eddyb) deduplicate this `associated_item` call with
+            // `program_clauses_for_associated_type_{value,def}`.
+            Some(DefKind::AssociatedTy) => match tcx.associated_item(def_id).container {
+                ty::AssociatedItemContainer::ImplContainer(_) =>
+                    program_clauses_for_associated_type_value(tcx, def_id),
+                ty::AssociatedItemContainer::TraitContainer(_) =>
+                    program_clauses_for_associated_type_def(tcx, def_id)
+            },
+            Some(DefKind::Struct)
+            | Some(DefKind::Enum)
+            | Some(DefKind::TyAlias)
+            | Some(DefKind::Union)
+            | Some(DefKind::Existential) => program_clauses_for_type_def(tcx, def_id),
+            _ => List::empty(),
+        },
         DefPathData::Impl => program_clauses_for_impl(tcx, def_id),
-        DefPathData::AssocTypeInImpl(..) => program_clauses_for_associated_type_value(tcx, def_id),
-        DefPathData::AssocTypeInTrait(..) => program_clauses_for_associated_type_def(tcx, def_id),
-        DefPathData::TypeNs(..) => program_clauses_for_type_def(tcx, def_id),
         _ => List::empty(),
     }
 }
diff --git a/src/test/ui/symbol-names/basic.stderr b/src/test/ui/symbol-names/basic.stderr
index 6ddd93d632e..7539cbada8b 100644
--- a/src/test/ui/symbol-names/basic.stderr
+++ b/src/test/ui/symbol-names/basic.stderr
@@ -1,4 +1,4 @@
-error: symbol-name(_ZN5basic4main17h08bcaf310214ed52E)
+error: symbol-name(_ZN5basic4main17hd72940ef9669d526E)
   --> $DIR/basic.rs:3:1
    |
 LL | #[rustc_symbol_name]
diff --git a/src/test/ui/symbol-names/impl1.stderr b/src/test/ui/symbol-names/impl1.stderr
index eda8646b5b4..20e48782a3a 100644
--- a/src/test/ui/symbol-names/impl1.stderr
+++ b/src/test/ui/symbol-names/impl1.stderr
@@ -1,4 +1,4 @@
-error: symbol-name(_ZN5impl13foo3Foo3bar17hc487d6ec13fe9124E)
+error: symbol-name(_ZN5impl13foo3Foo3bar17he53b9bee7600ed8dE)
   --> $DIR/impl1.rs:8:9
    |
 LL |         #[rustc_symbol_name]
@@ -10,7 +10,7 @@ error: def-path(foo::Foo::bar)
 LL |         #[rustc_def_path]
    |         ^^^^^^^^^^^^^^^^^
 
-error: symbol-name(_ZN5impl13bar33_$LT$impl$u20$impl1..foo..Foo$GT$3baz17h38577281258e1527E)
+error: symbol-name(_ZN5impl13bar33_$LT$impl$u20$impl1..foo..Foo$GT$3baz17h86c41f0462d901d4E)
   --> $DIR/impl1.rs:18:9
    |
 LL |         #[rustc_symbol_name]