Auto merge of #15053 - Veykril:crate-root-module-id, r=Veykril

internal: Add a CrateRootModuleId that encodes a module id that is always a crate root

Author: bors

crates/hir-def/src/find_path.rs

@@ -81,7 +81,7 @@ fn find_path_inner(
     }
 
     let def_map = from.def_map(db);
-    let crate_root = def_map.crate_root();
+    let crate_root = def_map.crate_root().into();
     // - if the item is a module, jump straight to module search
     if let ItemInNs::Types(ModuleDefId::ModuleId(module_id)) = item {
         let mut visited_modules = FxHashSet::default();
@@ -374,7 +374,7 @@ fn calculate_best_path(
         }
     }
     if let Some(module) = item.module(db) {
-        if module.def_map(db).block_id().is_some() && prefixed.is_some() {
+        if module.containing_block().is_some() && prefixed.is_some() {
             cov_mark::hit!(prefixed_in_block_expression);
             prefixed = Some(PrefixKind::Plain);
         }

crates/hir-def/src/item_tree.rs

@@ -101,7 +101,6 @@ pub struct ItemTree {
     top_level: SmallVec<[ModItem; 1]>,
     attrs: FxHashMap<AttrOwner, RawAttrs>,
 
-    // FIXME: Remove this indirection, an item tree is almost always non-empty?
     data: Option<Box<ItemTreeData>>,
 }
 
@@ -718,7 +717,6 @@ pub struct Mod {
 pub enum ModKind {
     /// `mod m { ... }`
     Inline { items: Box<[ModItem]> },
-
     /// `mod m;`
     Outline,
 }
@@ -892,10 +890,6 @@ impl ModItem {
         }
     }
 
-    pub fn downcast<N: ItemTreeNode>(self) -> Option<FileItemTreeId<N>> {
-        N::id_from_mod_item(self)
-    }
-
     pub fn ast_id(&self, tree: &ItemTree) -> FileAstId<ast::Item> {
         match self {
             ModItem::Import(it) => tree[it.index].ast_id().upcast(),

crates/hir-def/src/lib.rs

@@ -93,6 +93,46 @@ use crate::{
     },
 };
 
+/// A `ModuleId` that is always a crate's root module.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct CrateRootModuleId {
+    krate: CrateId,
+}
+
+impl CrateRootModuleId {
+    pub fn def_map(&self, db: &dyn db::DefDatabase) -> Arc<DefMap> {
+        db.crate_def_map(self.krate)
+    }
+
+    pub fn krate(self) -> CrateId {
+        self.krate
+    }
+}
+
+impl From<CrateRootModuleId> for ModuleId {
+    fn from(CrateRootModuleId { krate }: CrateRootModuleId) -> Self {
+        ModuleId { krate, block: None, local_id: DefMap::ROOT }
+    }
+}
+
+impl From<CrateRootModuleId> for ModuleDefId {
+    fn from(value: CrateRootModuleId) -> Self {
+        ModuleDefId::ModuleId(value.into())
+    }
+}
+
+impl TryFrom<ModuleId> for CrateRootModuleId {
+    type Error = ();
+
+    fn try_from(ModuleId { krate, block, local_id }: ModuleId) -> Result<Self, Self::Error> {
+        if block.is_none() && local_id == DefMap::ROOT {
+            Ok(CrateRootModuleId { krate })
+        } else {
+            Err(())
+        }
+    }
+}
+
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct ModuleId {
     krate: CrateId,
@@ -314,8 +354,7 @@ impl_intern!(MacroRulesId, MacroRulesLoc, intern_macro_rules, lookup_intern_macr
 pub struct ProcMacroId(salsa::InternId);
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct ProcMacroLoc {
-    // FIXME: this should be a crate? or just a crate-root module
-    pub container: ModuleId,
+    pub container: CrateRootModuleId,
     pub id: ItemTreeId<Function>,
     pub expander: ProcMacroExpander,
     pub kind: ProcMacroKind,
@@ -903,7 +942,7 @@ impl HasModule for MacroId {
         match self {
             MacroId::MacroRulesId(it) => it.lookup(db).container,
             MacroId::Macro2Id(it) => it.lookup(db).container,
-            MacroId::ProcMacroId(it) => it.lookup(db).container,
+            MacroId::ProcMacroId(it) => it.lookup(db).container.into(),
         }
     }
 }

crates/hir-def/src/nameres.rs

@@ -77,8 +77,8 @@ use crate::{
     path::ModPath,
     per_ns::PerNs,
     visibility::Visibility,
-    AstId, BlockId, BlockLoc, FunctionId, LocalModuleId, Lookup, MacroExpander, MacroId, ModuleId,
-    ProcMacroId,
+    AstId, BlockId, BlockLoc, CrateRootModuleId, FunctionId, LocalModuleId, Lookup, MacroExpander,
+    MacroId, ModuleId, ProcMacroId,
 };
 
 /// Contains the results of (early) name resolution.
@@ -93,7 +93,10 @@ use crate::{
 #[derive(Debug, PartialEq, Eq)]
 pub struct DefMap {
     _c: Count<Self>,
+    /// When this is a block def map, this will hold the block id of the the block and module that
+    /// contains this block.
     block: Option<BlockInfo>,
+    /// The modules and their data declared in this crate.
     modules: Arena<ModuleData>,
     krate: CrateId,
     /// The prelude module for this crate. This either comes from an import
@@ -111,15 +114,18 @@ pub struct DefMap {
     /// attributes.
     derive_helpers_in_scope: FxHashMap<AstId<ast::Item>, Vec<(Name, MacroId, MacroCallId)>>,
 
+    /// The diagnostics that need to be emitted for this crate.
     diagnostics: Vec<DefDiagnostic>,
 
+    /// The crate data that is shared between a crate's def map and all its block def maps.
     data: Arc<DefMapCrateData>,
 }
 
 /// Data that belongs to a crate which is shared between a crate's def map and all its block def maps.
 #[derive(Clone, Debug, PartialEq, Eq)]
 struct DefMapCrateData {
-    extern_prelude: FxHashMap<Name, ModuleId>,
+    /// The extern prelude which contains all root modules of external crates that are in scope.
+    extern_prelude: FxHashMap<Name, CrateRootModuleId>,
 
     /// Side table for resolving derive helpers.
     exported_derives: FxHashMap<MacroDefId, Box<[Name]>>,
@@ -279,6 +285,7 @@ pub struct ModuleData {
 }
 
 impl DefMap {
+    /// The module id of a crate or block root.
     pub const ROOT: LocalModuleId = LocalModuleId::from_raw(la_arena::RawIdx::from_u32(0));
 
     pub(crate) fn crate_def_map_query(db: &dyn DefDatabase, krate: CrateId) -> Arc<DefMap> {
@@ -419,20 +426,20 @@ impl DefMap {
     }
 
     pub(crate) fn extern_prelude(&self) -> impl Iterator<Item = (&Name, ModuleId)> + '_ {
-        self.data.extern_prelude.iter().map(|(name, def)| (name, *def))
+        self.data.extern_prelude.iter().map(|(name, &def)| (name, def.into()))
     }
 
     pub(crate) fn macro_use_prelude(&self) -> impl Iterator<Item = (&Name, MacroId)> + '_ {
-        self.macro_use_prelude.iter().map(|(name, def)| (name, *def))
+        self.macro_use_prelude.iter().map(|(name, &def)| (name, def))
     }
 
     pub fn module_id(&self, local_id: LocalModuleId) -> ModuleId {
         let block = self.block.map(|b| b.block);
         ModuleId { krate: self.krate, local_id, block }
     }
 
-    pub(crate) fn crate_root(&self) -> ModuleId {
-        ModuleId { krate: self.krate, block: None, local_id: DefMap::ROOT }
+    pub fn crate_root(&self) -> CrateRootModuleId {
+        CrateRootModuleId { krate: self.krate }
     }
 
     pub(crate) fn resolve_path(
@@ -476,7 +483,7 @@ impl DefMap {
     ///
     /// If `f` returns `Some(val)`, iteration is stopped and `Some(val)` is returned. If `f` returns
     /// `None`, iteration continues.
-    pub fn with_ancestor_maps<T>(
+    pub(crate) fn with_ancestor_maps<T>(
         &self,
         db: &dyn DefDatabase,
         local_mod: LocalModuleId,

crates/hir-def/src/nameres/collector.rs

@@ -51,11 +51,11 @@ use crate::{
     per_ns::PerNs,
     tt,
     visibility::{RawVisibility, Visibility},
-    AdtId, AstId, AstIdWithPath, ConstLoc, EnumLoc, EnumVariantId, ExternBlockLoc, FunctionId,
-    FunctionLoc, ImplLoc, Intern, ItemContainerId, LocalModuleId, Macro2Id, Macro2Loc,
-    MacroExpander, MacroId, MacroRulesId, MacroRulesLoc, ModuleDefId, ModuleId, ProcMacroId,
-    ProcMacroLoc, StaticLoc, StructLoc, TraitAliasLoc, TraitLoc, TypeAliasLoc, UnionLoc,
-    UnresolvedMacro,
+    AdtId, AstId, AstIdWithPath, ConstLoc, CrateRootModuleId, EnumLoc, EnumVariantId,
+    ExternBlockLoc, FunctionId, FunctionLoc, ImplLoc, Intern, ItemContainerId, LocalModuleId,
+    Macro2Id, Macro2Loc, MacroExpander, MacroId, MacroRulesId, MacroRulesLoc, ModuleDefId,
+    ModuleId, ProcMacroId, ProcMacroLoc, StaticLoc, StructLoc, TraitAliasLoc, TraitLoc,
+    TypeAliasLoc, UnionLoc, UnresolvedMacro,
 };
 
 static GLOB_RECURSION_LIMIT: Limit = Limit::new(100);
@@ -274,8 +274,6 @@ impl DefCollector<'_> {
 
         let file_id = self.db.crate_graph()[self.def_map.krate].root_file_id;
         let item_tree = self.db.file_item_tree(file_id.into());
-        let module_id = DefMap::ROOT;
-
         let attrs = item_tree.top_level_attrs(self.db, self.def_map.krate);
         let crate_data = Arc::get_mut(&mut self.def_map.data).unwrap();
 
@@ -285,10 +283,9 @@ impl DefCollector<'_> {
 
         for (name, dep) in &self.deps {
             if dep.is_prelude() {
-                crate_data.extern_prelude.insert(
-                    name.clone(),
-                    ModuleId { krate: dep.crate_id, block: None, local_id: DefMap::ROOT },
-                );
+                crate_data
+                    .extern_prelude
+                    .insert(name.clone(), CrateRootModuleId { krate: dep.crate_id });
             }
         }
 
@@ -374,7 +371,7 @@ impl DefCollector<'_> {
         ModCollector {
             def_collector: self,
             macro_depth: 0,
-            module_id,
+            module_id: DefMap::ROOT,
             tree_id: TreeId::new(file_id.into(), None),
             item_tree: &item_tree,
             mod_dir: ModDir::root(),
@@ -384,8 +381,6 @@ impl DefCollector<'_> {
 
     fn seed_with_inner(&mut self, tree_id: TreeId) {
         let item_tree = tree_id.item_tree(self.db);
-        let module_id = DefMap::ROOT;
-
         let is_cfg_enabled = item_tree
             .top_level_attrs(self.db, self.def_map.krate)
             .cfg()
@@ -394,7 +389,7 @@ impl DefCollector<'_> {
             ModCollector {
                 def_collector: self,
                 macro_depth: 0,
-                module_id,
+                module_id: DefMap::ROOT,
                 tree_id,
                 item_tree: &item_tree,
                 mod_dir: ModDir::root(),
@@ -604,8 +599,6 @@ impl DefCollector<'_> {
         if self.def_map.block.is_some() {
             return;
         }
-        let crate_root = self.def_map.module_id(DefMap::ROOT);
-
         let kind = def.kind.to_basedb_kind();
         let (expander, kind) =
             match self.proc_macros.as_ref().map(|it| it.iter().find(|(n, _)| n == &def.name)) {
@@ -614,7 +607,8 @@ impl DefCollector<'_> {
             };
 
         let proc_macro_id =
-            ProcMacroLoc { container: crate_root, id, expander, kind }.intern(self.db);
+            ProcMacroLoc { container: self.def_map.crate_root(), id, expander, kind }
+                .intern(self.db);
         self.define_proc_macro(def.name.clone(), proc_macro_id);
         let crate_data = Arc::get_mut(&mut self.def_map.data).unwrap();
         if let ProcMacroKind::CustomDerive { helpers } = def.kind {
@@ -831,16 +825,12 @@ impl DefCollector<'_> {
         }
     }
 
-    fn resolve_extern_crate(&self, name: &Name) -> Option<ModuleId> {
+    fn resolve_extern_crate(&self, name: &Name) -> Option<CrateRootModuleId> {
         if *name == name!(self) {
             cov_mark::hit!(extern_crate_self_as);
             Some(self.def_map.crate_root())
         } else {
-            self.deps.get(name).map(|dep| ModuleId {
-                krate: dep.crate_id,
-                block: None,
-                local_id: DefMap::ROOT,
-            })
+            self.deps.get(name).map(|dep| CrateRootModuleId { krate: dep.crate_id })
         }
     }
 
@@ -883,10 +873,12 @@ impl DefCollector<'_> {
                 {
                     if let (Some(ModuleDefId::ModuleId(def)), Some(name)) = (def.take_types(), name)
                     {
-                        Arc::get_mut(&mut self.def_map.data)
-                            .unwrap()
-                            .extern_prelude
-                            .insert(name.clone(), def);
+                        if let Ok(def) = def.try_into() {
+                            Arc::get_mut(&mut self.def_map.data)
+                                .unwrap()
+                                .extern_prelude
+                                .insert(name.clone(), def);
+                        }
                     }
                 }
 
@@ -1791,13 +1783,11 @@ impl ModCollector<'_, '_> {
 
         let target_crate =
             match self.def_collector.resolve_extern_crate(&self.item_tree[extern_crate].name) {
-                Some(m) => {
-                    if m == self.def_collector.def_map.module_id(self.module_id) {
-                        cov_mark::hit!(ignore_macro_use_extern_crate_self);
-                        return;
-                    }
-                    m.krate
+                Some(m) if m.krate == self.def_collector.def_map.krate => {
+                    cov_mark::hit!(ignore_macro_use_extern_crate_self);
+                    return;
                 }
+                Some(m) => m.krate,
                 None => return,
             };
 

crates/hir-def/src/resolver.rs

@@ -21,11 +21,11 @@ use crate::{
     path::{ModPath, Path, PathKind},
     per_ns::PerNs,
     visibility::{RawVisibility, Visibility},
-    AdtId, AssocItemId, ConstId, ConstParamId, DefWithBodyId, EnumId, EnumVariantId, ExternBlockId,
-    FunctionId, GenericDefId, GenericParamId, HasModule, ImplId, ItemContainerId, LifetimeParamId,
-    LocalModuleId, Lookup, Macro2Id, MacroId, MacroRulesId, ModuleDefId, ModuleId, ProcMacroId,
-    StaticId, StructId, TraitAliasId, TraitId, TypeAliasId, TypeOrConstParamId, TypeOwnerId,
-    TypeParamId, VariantId,
+    AdtId, AssocItemId, ConstId, ConstParamId, CrateRootModuleId, DefWithBodyId, EnumId,
+    EnumVariantId, ExternBlockId, FunctionId, GenericDefId, GenericParamId, HasModule, ImplId,
+    ItemContainerId, LifetimeParamId, LocalModuleId, Lookup, Macro2Id, MacroId, MacroRulesId,
+    ModuleDefId, ModuleId, ProcMacroId, StaticId, StructId, TraitAliasId, TraitId, TypeAliasId,
+    TypeOrConstParamId, TypeOwnerId, TypeParamId, VariantId,
 };
 
 #[derive(Debug, Clone)]
@@ -946,6 +946,15 @@ impl HasResolver for ModuleId {
     }
 }
 
+impl HasResolver for CrateRootModuleId {
+    fn resolver(self, db: &dyn DefDatabase) -> Resolver {
+        Resolver {
+            scopes: vec![],
+            module_scope: ModuleItemMap { def_map: self.def_map(db), module_id: DefMap::ROOT },
+        }
+    }
+}
+
 impl HasResolver for TraitId {
     fn resolver(self, db: &dyn DefDatabase) -> Resolver {
         self.lookup(db).container.resolver(db).push_generic_params_scope(db, self.into())

crates/hir-expand/src/ast_id_map.rs

@@ -20,7 +20,7 @@ use syntax::{ast, AstNode, AstPtr, SyntaxNode, SyntaxNodePtr};
 /// `AstId` points to an AST node in a specific file.
 pub struct FileAstId<N: AstNode> {
     raw: ErasedFileAstId,
-    _ty: PhantomData<fn() -> N>,
+    covariant: PhantomData<fn() -> N>,
 }
 
 impl<N: AstNode> Clone for FileAstId<N> {
@@ -54,7 +54,7 @@ impl<N: AstNode> FileAstId<N> {
     where
         N: Into<M>,
     {
-        FileAstId { raw: self.raw, _ty: PhantomData }
+        FileAstId { raw: self.raw, covariant: PhantomData }
     }
 }
 
@@ -122,7 +122,7 @@ impl AstIdMap {
 
     pub fn ast_id<N: AstNode>(&self, item: &N) -> FileAstId<N> {
         let raw = self.erased_ast_id(item.syntax());
-        FileAstId { raw, _ty: PhantomData }
+        FileAstId { raw, covariant: PhantomData }
     }
 
     pub fn get<N: AstNode>(&self, id: FileAstId<N>) -> AstPtr<N> {