resolve: Merge `NameBindingKind::Module` into `NameBindingKind::Res`

9 files changed, 61 insertions, 99 deletions

diff --git a/compiler/rustc_hir/src/def.rs b/compiler/rustc_hir/src/def.rs
index df010f87098..ca57c4f3164 100644
--- a/compiler/rustc_hir/src/def.rs
+++ b/compiler/rustc_hir/src/def.rs
@@ -295,6 +295,12 @@ impl DefKind {
         }
     }
 
+    /// This is a "module" in name resolution sense.
+    #[inline]
+    pub fn is_module_like(self) -> bool {
+        matches!(self, DefKind::Mod | DefKind::Enum | DefKind::Trait)
+    }
+
     #[inline]
     pub fn is_fn_like(self) -> bool {
         matches!(
@@ -720,6 +726,15 @@ impl<Id> Res<Id> {
         }
     }
 
+    /// If this is a "module" in name resolution sense, return its `DefId`.
+    #[inline]
+    pub fn module_like_def_id(&self) -> Option<DefId> {
+        match self {
+            Res::Def(def_kind, def_id) if def_kind.is_module_like() => Some(*def_id),
+            _ => None,
+        }
+    }
+
     /// A human readable name for the res kind ("function", "module", etc.).
     pub fn descr(&self) -> &'static str {
         match *self {
diff --git a/compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs b/compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs
index 19954459cb5..57a672c45f7 100644
--- a/compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs
+++ b/compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs
@@ -3,7 +3,7 @@ use std::mem;
 use std::sync::Arc;
 
 use rustc_attr_data_structures::Deprecation;
-use rustc_hir::def::{CtorKind, DefKind, Res};
+use rustc_hir::def::{CtorKind, DefKind};
 use rustc_hir::def_id::{CrateNum, DefId, DefIdMap, LOCAL_CRATE};
 use rustc_hir::definitions::{DefKey, DefPath, DefPathHash};
 use rustc_middle::arena::ArenaAllocatable;
@@ -510,10 +510,7 @@ pub(in crate::rmeta) fn provide(providers: &mut Providers) {
                         }
                         Entry::Vacant(entry) => {
                             entry.insert(parent);
-                            if matches!(
-                                child.res,
-                                Res::Def(DefKind::Mod | DefKind::Enum | DefKind::Trait, _)
-                            ) {
+                            if child.res.module_like_def_id().is_some() {
                                 bfs_queue.push_back(def_id);
                             }
                         }
diff --git a/compiler/rustc_middle/src/ty/print/pretty.rs b/compiler/rustc_middle/src/ty/print/pretty.rs
index 7c48a4b0885..8f0f9b21dc1 100644
--- a/compiler/rustc_middle/src/ty/print/pretty.rs
+++ b/compiler/rustc_middle/src/ty/print/pretty.rs
@@ -3454,9 +3454,7 @@ fn for_each_def(tcx: TyCtxt<'_>, mut collect_fn: impl for<'b> FnMut(&'b Ident, N
                         collect_fn(&child.ident, ns, def_id);
                     }
 
-                    if matches!(defkind, DefKind::Mod | DefKind::Enum | DefKind::Trait)
-                        && seen_defs.insert(def_id)
-                    {
+                    if defkind.is_module_like() && seen_defs.insert(def_id) {
                         queue.push(def_id);
                     }
                 }
diff --git a/compiler/rustc_resolve/src/build_reduced_graph.rs b/compiler/rustc_resolve/src/build_reduced_graph.rs
index 6979d89a8e7..a51cdbe76ee 100644
--- a/compiler/rustc_resolve/src/build_reduced_graph.rs
+++ b/compiler/rustc_resolve/src/build_reduced_graph.rs
@@ -39,21 +39,6 @@ use crate::{
 
 type Res = def::Res<NodeId>;
 
-impl<'ra, Id: Into<DefId>> ToNameBinding<'ra>
-    for (Module<'ra>, ty::Visibility<Id>, Span, LocalExpnId)
-{
-    fn to_name_binding(self, arenas: &'ra ResolverArenas<'ra>) -> NameBinding<'ra> {
-        arenas.alloc_name_binding(NameBindingData {
-            kind: NameBindingKind::Module(self.0),
-            ambiguity: None,
-            warn_ambiguity: false,
-            vis: self.1.to_def_id(),
-            span: self.2,
-            expansion: self.3,
-        })
-    }
-}
-
 impl<'ra, Id: Into<DefId>> ToNameBinding<'ra> for (Res, ty::Visibility<Id>, Span, LocalExpnId) {
     fn to_name_binding(self, arenas: &'ra ResolverArenas<'ra>) -> NameBinding<'ra> {
         arenas.alloc_name_binding(NameBindingData {
@@ -121,7 +106,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         if !def_id.is_local() {
             // Query `def_kind` is not used because query system overhead is too expensive here.
             let def_kind = self.cstore().def_kind_untracked(def_id);
-            if let DefKind::Mod | DefKind::Enum | DefKind::Trait = def_kind {
+            if def_kind.is_module_like() {
                 let parent = self
                     .tcx
                     .opt_parent(def_id)
@@ -223,12 +208,11 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         let expansion = parent_scope.expansion;
         // Record primary definitions.
         match res {
-            Res::Def(DefKind::Mod | DefKind::Enum | DefKind::Trait, def_id) => {
-                let module = self.expect_module(def_id);
-                self.define(parent, ident, TypeNS, (module, vis, span, expansion));
-            }
             Res::Def(
-                DefKind::Struct
+                DefKind::Mod
+                | DefKind::Enum
+                | DefKind::Trait
+                | DefKind::Struct
                 | DefKind::Union
                 | DefKind::Variant
                 | DefKind::TyAlias
@@ -766,7 +750,12 @@ impl<'a, 'ra, 'tcx> BuildReducedGraphVisitor<'a, 'ra, 'tcx> {
             }
 
             ItemKind::Mod(_, ident, ref mod_kind) => {
-                let module = self.r.new_module(
+                self.r.define(parent, ident, TypeNS, (res, vis, sp, expansion));
+
+                if let ast::ModKind::Loaded(_, _, _, Err(_)) = mod_kind {
+                    self.r.mods_with_parse_errors.insert(def_id);
+                }
+                self.parent_scope.module = self.r.new_module(
                     Some(parent),
                     ModuleKind::Def(def_kind, def_id, Some(ident.name)),
                     expansion.to_expn_id(),
@@ -774,14 +763,6 @@ impl<'a, 'ra, 'tcx> BuildReducedGraphVisitor<'a, 'ra, 'tcx> {
                     parent.no_implicit_prelude
                         || ast::attr::contains_name(&item.attrs, sym::no_implicit_prelude),
                 );
-                self.r.define(parent, ident, TypeNS, (module, vis, sp, expansion));
-
-                if let ast::ModKind::Loaded(_, _, _, Err(_)) = mod_kind {
-                    self.r.mods_with_parse_errors.insert(def_id);
-                }
-
-                // Descend into the module.
-                self.parent_scope.module = module;
             }
 
             // These items live in the value namespace.
@@ -804,15 +785,15 @@ impl<'a, 'ra, 'tcx> BuildReducedGraphVisitor<'a, 'ra, 'tcx> {
             }
 
             ItemKind::Enum(ident, _, _) | ItemKind::Trait(box ast::Trait { ident, .. }) => {
-                let module = self.r.new_module(
+                self.r.define(parent, ident, TypeNS, (res, vis, sp, expansion));
+
+                self.parent_scope.module = self.r.new_module(
                     Some(parent),
                     ModuleKind::Def(def_kind, def_id, Some(ident.name)),
                     expansion.to_expn_id(),
                     item.span,
                     parent.no_implicit_prelude,
                 );
-                self.r.define(parent, ident, TypeNS, (module, vis, sp, expansion));
-                self.parent_scope.module = module;
             }
 
             // These items live in both the type and value namespaces.
@@ -920,8 +901,9 @@ impl<'a, 'ra, 'tcx> BuildReducedGraphVisitor<'a, 'ra, 'tcx> {
         }
         .map(|module| {
             let used = self.process_macro_use_imports(item, module);
+            let res = module.res().unwrap();
             let vis = ty::Visibility::<LocalDefId>::Public;
-            let binding = (module, vis, sp, expansion).to_name_binding(self.r.arenas);
+            let binding = (res, vis, sp, expansion).to_name_binding(self.r.arenas);
             (used, Some(ModuleOrUniformRoot::Module(module)), binding)
         })
         .unwrap_or((true, None, self.r.dummy_binding));
diff --git a/compiler/rustc_resolve/src/diagnostics.rs b/compiler/rustc_resolve/src/diagnostics.rs
index 93d848787ef..11e4a729ae2 100644
--- a/compiler/rustc_resolve/src/diagnostics.rs
+++ b/compiler/rustc_resolve/src/diagnostics.rs
@@ -232,12 +232,12 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             return;
         }
 
-        let old_kind = match (ns, old_binding.module()) {
+        let old_kind = match (ns, old_binding.res()) {
             (ValueNS, _) => "value",
             (MacroNS, _) => "macro",
             (TypeNS, _) if old_binding.is_extern_crate() => "extern crate",
-            (TypeNS, Some(module)) if module.is_normal() => "module",
-            (TypeNS, Some(module)) if module.is_trait() => "trait",
+            (TypeNS, Res::Def(DefKind::Mod, _)) => "module",
+            (TypeNS, Res::Def(DefKind::Trait, _)) => "trait",
             (TypeNS, _) => "type",
         };
 
@@ -1319,7 +1319,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                 }
 
                 // collect submodules to explore
-                if let Some(module) = name_binding.module() {
+                if let Some(def_id) = name_binding.res().module_like_def_id() {
                     // form the path
                     let mut path_segments = path_segments.clone();
                     path_segments.push(ast::PathSegment::from_ident(ident));
@@ -1339,14 +1339,14 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
 
                     if !is_extern_crate_that_also_appears_in_prelude || alias_import {
                         // add the module to the lookup
-                        if seen_modules.insert(module.def_id()) {
+                        if seen_modules.insert(def_id) {
                             if via_import { &mut worklist_via_import } else { &mut worklist }.push(
                                 (
-                                    module,
+                                    this.expect_module(def_id),
                                     path_segments,
                                     child_accessible,
                                     child_doc_visible,
-                                    is_stable && this.is_stable(module.def_id(), name_binding.span),
+                                    is_stable && this.is_stable(def_id, name_binding.span),
                                 ),
                             );
                         }
@@ -2094,7 +2094,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                         true, // re-export
                     ));
                 }
-                NameBindingKind::Res(_) | NameBindingKind::Module(_) => {}
+                NameBindingKind::Res(_) => {}
             }
             let first = binding == first_binding;
             let def_span = self.tcx.sess.source_map().guess_head_span(binding.span);
@@ -2306,25 +2306,11 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                     .ok()
                 };
                 if let Some(binding) = binding {
-                    let mut found = |what| {
-                        msg = format!(
-                            "expected {}, found {} `{}` in {}",
-                            ns.descr(),
-                            what,
-                            ident,
-                            parent
-                        )
-                    };
-                    if binding.module().is_some() {
-                        found("module")
-                    } else {
-                        match binding.res() {
-                            // Avoid using TyCtxt::def_kind_descr in the resolver, because it
-                            // indirectly *calls* the resolver, and would cause a query cycle.
-                            Res::Def(kind, id) => found(kind.descr(id)),
-                            _ => found(ns_to_try.descr()),
-                        }
-                    }
+                    msg = format!(
+                        "expected {}, found {} `{ident}` in {parent}",
+                        ns.descr(),
+                        binding.res().descr(),
+                    );
                 };
             }
             (msg, None)
diff --git a/compiler/rustc_resolve/src/ident.rs b/compiler/rustc_resolve/src/ident.rs
index 99297de40d5..04f9e35b6b4 100644
--- a/compiler/rustc_resolve/src/ident.rs
+++ b/compiler/rustc_resolve/src/ident.rs
@@ -1637,11 +1637,11 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                     }
 
                     let maybe_assoc = opt_ns != Some(MacroNS) && PathSource::Type.is_expected(res);
-                    if let Some(next_module) = binding.module() {
-                        if self.mods_with_parse_errors.contains(&next_module.def_id()) {
+                    if let Some(def_id) = binding.res().module_like_def_id() {
+                        if self.mods_with_parse_errors.contains(&def_id) {
                             module_had_parse_errors = true;
                         }
-                        module = Some(ModuleOrUniformRoot::Module(next_module));
+                        module = Some(ModuleOrUniformRoot::Module(self.expect_module(def_id)));
                         record_segment_res(self, res);
                     } else if res == Res::ToolMod && !is_last && opt_ns.is_some() {
                         if binding.is_import() {
diff --git a/compiler/rustc_resolve/src/imports.rs b/compiler/rustc_resolve/src/imports.rs
index 40c63a3edf3..2fa20b25469 100644
--- a/compiler/rustc_resolve/src/imports.rs
+++ b/compiler/rustc_resolve/src/imports.rs
@@ -679,9 +679,6 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                             NameBindingKind::Res(res) => {
                                 Some(self.def_id_to_node_id(res.def_id().expect_local()))
                             }
-                            NameBindingKind::Module(module) => {
-                                Some(self.def_id_to_node_id(module.def_id().expect_local()))
-                            }
                             NameBindingKind::Import { import, .. } => import.id(),
                         };
                         if let Some(binding_id) = binding_id {
diff --git a/compiler/rustc_resolve/src/late/diagnostics.rs b/compiler/rustc_resolve/src/late/diagnostics.rs
index b669796bb02..a4601cb44eb 100644
--- a/compiler/rustc_resolve/src/late/diagnostics.rs
+++ b/compiler/rustc_resolve/src/late/diagnostics.rs
@@ -2656,18 +2656,17 @@ impl<'ast, 'ra, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
                 if result.is_some() || !name_binding.vis.is_visible_locally() {
                     return;
                 }
-                if let Some(module) = name_binding.module() {
+                if let Some(module_def_id) = name_binding.res().module_like_def_id() {
                     // form the path
                     let mut path_segments = path_segments.clone();
                     path_segments.push(ast::PathSegment::from_ident(ident));
-                    let module_def_id = module.def_id();
                     let doc_visible = doc_visible
                         && (module_def_id.is_local() || !r.tcx.is_doc_hidden(module_def_id));
                     if module_def_id == def_id {
                         let path =
                             Path { span: name_binding.span, segments: path_segments, tokens: None };
                         result = Some((
-                            module,
+                            r.expect_module(module_def_id),
                             ImportSuggestion {
                                 did: Some(def_id),
                                 descr: "module",
@@ -2682,6 +2681,7 @@ impl<'ast, 'ra, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
                     } else {
                         // add the module to the lookup
                         if seen_modules.insert(module_def_id) {
+                            let module = r.expect_module(module_def_id);
                             worklist.push((module, path_segments, doc_visible));
                         }
                     }
diff --git a/compiler/rustc_resolve/src/lib.rs b/compiler/rustc_resolve/src/lib.rs
index c2b3451d4a1..eb2b9260483 100644
--- a/compiler/rustc_resolve/src/lib.rs
+++ b/compiler/rustc_resolve/src/lib.rs
@@ -674,7 +674,6 @@ impl<'ra> Module<'ra> {
         }
     }
 
-    // Public for rustdoc.
     fn def_id(self) -> DefId {
         self.opt_def_id().expect("`ModuleData::def_id` is called on a block module")
     }
@@ -782,7 +781,6 @@ impl<'ra> ToNameBinding<'ra> for NameBinding<'ra> {
 #[derive(Clone, Copy, Debug)]
 enum NameBindingKind<'ra> {
     Res(Res),
-    Module(Module<'ra>),
     Import { binding: NameBinding<'ra>, import: Import<'ra> },
 }
 
@@ -875,18 +873,9 @@ struct AmbiguityError<'ra> {
 }
 
 impl<'ra> NameBindingData<'ra> {
-    fn module(&self) -> Option<Module<'ra>> {
-        match self.kind {
-            NameBindingKind::Module(module) => Some(module),
-            NameBindingKind::Import { binding, .. } => binding.module(),
-            _ => None,
-        }
-    }
-
     fn res(&self) -> Res {
         match self.kind {
             NameBindingKind::Res(res) => res,
-            NameBindingKind::Module(module) => module.res().unwrap(),
             NameBindingKind::Import { binding, .. } => binding.res(),
         }
     }
@@ -921,7 +910,7 @@ impl<'ra> NameBindingData<'ra> {
                 DefKind::Variant | DefKind::Ctor(CtorOf::Variant, ..),
                 _,
             )) => true,
-            NameBindingKind::Res(..) | NameBindingKind::Module(..) => false,
+            NameBindingKind::Res(..) => false,
         }
     }
 
@@ -930,11 +919,7 @@ impl<'ra> NameBindingData<'ra> {
             NameBindingKind::Import { import, .. } => {
                 matches!(import.kind, ImportKind::ExternCrate { .. })
             }
-            NameBindingKind::Module(module)
-                if let ModuleKind::Def(DefKind::Mod, def_id, _) = module.kind =>
-            {
-                def_id.is_crate_root()
-            }
+            NameBindingKind::Res(Res::Def(_, def_id)) => def_id.is_crate_root(),
             _ => false,
         }
     }
@@ -1279,7 +1264,8 @@ impl<'ra> ResolverArenas<'ra> {
         if let Some(def_id) = def_id {
             module_map.insert(def_id, module);
             let vis = ty::Visibility::<DefId>::Public;
-            let binding = (module, vis, module.span, LocalExpnId::ROOT).to_name_binding(self);
+            let res = module.res().unwrap();
+            let binding = (res, vis, module.span, LocalExpnId::ROOT).to_name_binding(self);
             module_self_bindings.insert(module, binding);
         }
         module
@@ -1838,7 +1824,8 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         module.ensure_traits(self);
         let traits = module.traits.borrow();
         for (trait_name, trait_binding) in traits.as_ref().unwrap().iter() {
-            if self.trait_may_have_item(trait_binding.module(), assoc_item) {
+            let trait_module = self.get_module(trait_binding.res().def_id());
+            if self.trait_may_have_item(trait_module, assoc_item) {
                 let def_id = trait_binding.res().def_id();
                 let import_ids = self.find_transitive_imports(&trait_binding.kind, *trait_name);
                 found_traits.push(TraitCandidate { def_id, import_ids });
@@ -2174,9 +2161,9 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                 } else {
                     self.crate_loader(|c| c.maybe_process_path_extern(ident.name))?
                 };
-                let crate_root = self.expect_module(crate_id.as_def_id());
+                let res = Res::Def(DefKind::Mod, crate_id.as_def_id());
                 let vis = ty::Visibility::<DefId>::Public;
-                (crate_root, vis, DUMMY_SP, LocalExpnId::ROOT).to_name_binding(self.arenas)
+                (res, vis, DUMMY_SP, LocalExpnId::ROOT).to_name_binding(self.arenas)
             })
         });