mv compiler to compiler/

compiler/rustc_hir/src/definitions.rs

@@ -0,0 +1,457 @@
+//! For each definition, we track the following data. A definition
+//! here is defined somewhat circularly as "something with a `DefId`",
+//! but it generally corresponds to things like structs, enums, etc.
+//! There are also some rather random cases (like const initializer
+//! expressions) that are mostly just leftovers.
+
+pub use crate::def_id::DefPathHash;
+use crate::def_id::{CrateNum, DefId, DefIndex, LocalDefId, CRATE_DEF_INDEX, LOCAL_CRATE};
+use crate::hir;
+
+use rustc_ast::crate_disambiguator::CrateDisambiguator;
+use rustc_data_structures::fx::FxHashMap;
+use rustc_data_structures::stable_hasher::StableHasher;
+use rustc_index::vec::IndexVec;
+use rustc_span::hygiene::ExpnId;
+use rustc_span::symbol::{sym, Symbol};
+
+use std::fmt::Write;
+use std::hash::Hash;
+use tracing::debug;
+
+/// The `DefPathTable` maps `DefIndex`es to `DefKey`s and vice versa.
+/// Internally the `DefPathTable` holds a tree of `DefKey`s, where each `DefKey`
+/// stores the `DefIndex` of its parent.
+/// There is one `DefPathTable` for each crate.
+#[derive(Clone, Default)]
+pub struct DefPathTable {
+    index_to_key: IndexVec<DefIndex, DefKey>,
+    def_path_hashes: IndexVec<DefIndex, DefPathHash>,
+}
+
+impl DefPathTable {
+    fn allocate(&mut self, key: DefKey, def_path_hash: DefPathHash) -> DefIndex {
+        let index = {
+            let index = DefIndex::from(self.index_to_key.len());
+            debug!("DefPathTable::insert() - {:?} <-> {:?}", key, index);
+            self.index_to_key.push(key);
+            index
+        };
+        self.def_path_hashes.push(def_path_hash);
+        debug_assert!(self.def_path_hashes.len() == self.index_to_key.len());
+        index
+    }
+
+    #[inline(always)]
+    pub fn def_key(&self, index: DefIndex) -> DefKey {
+        self.index_to_key[index]
+    }
+
+    #[inline(always)]
+    pub fn def_path_hash(&self, index: DefIndex) -> DefPathHash {
+        let hash = self.def_path_hashes[index];
+        debug!("def_path_hash({:?}) = {:?}", index, hash);
+        hash
+    }
+
+    pub fn num_def_ids(&self) -> usize {
+        self.index_to_key.len()
+    }
+
+    pub fn enumerated_keys_and_path_hashes(
+        &self,
+    ) -> impl Iterator<Item = (DefIndex, &DefKey, &DefPathHash)> + '_ {
+        self.index_to_key
+            .iter_enumerated()
+            .map(move |(index, key)| (index, key, &self.def_path_hashes[index]))
+    }
+
+    pub fn all_def_path_hashes_and_def_ids(
+        &self,
+        krate: CrateNum,
+    ) -> impl Iterator<Item = (DefPathHash, DefId)> + '_ {
+        self.def_path_hashes
+            .iter_enumerated()
+            .map(move |(index, hash)| (*hash, DefId { krate, index }))
+    }
+}
+
+/// The definition table containing node definitions.
+/// It holds the `DefPathTable` for `LocalDefId`s/`DefPath`s.
+/// It also stores mappings to convert `LocalDefId`s to/from `HirId`s.
+#[derive(Clone)]
+pub struct Definitions {
+    table: DefPathTable,
+
+    // FIXME(eddyb) ideally all `LocalDefId`s would be HIR owners.
+    pub(super) def_id_to_hir_id: IndexVec<LocalDefId, Option<hir::HirId>>,
+    /// The reverse mapping of `def_id_to_hir_id`.
+    pub(super) hir_id_to_def_id: FxHashMap<hir::HirId, LocalDefId>,
+
+    /// If `ExpnId` is an ID of some macro expansion,
+    /// then `DefId` is the normal module (`mod`) in which the expanded macro was defined.
+    parent_modules_of_macro_defs: FxHashMap<ExpnId, DefId>,
+    /// Item with a given `LocalDefId` was defined during macro expansion with ID `ExpnId`.
+    expansions_that_defined: FxHashMap<LocalDefId, ExpnId>,
+}
+
+/// A unique identifier that we can use to lookup a definition
+/// precisely. It combines the index of the definition's parent (if
+/// any) with a `DisambiguatedDefPathData`.
+#[derive(Copy, Clone, PartialEq, Debug, Encodable, Decodable)]
+pub struct DefKey {
+    /// The parent path.
+    pub parent: Option<DefIndex>,
+
+    /// The identifier of this node.
+    pub disambiguated_data: DisambiguatedDefPathData,
+}
+
+impl DefKey {
+    fn compute_stable_hash(&self, parent_hash: DefPathHash) -> DefPathHash {
+        let mut hasher = StableHasher::new();
+
+        // We hash a `0u8` here to disambiguate between regular `DefPath` hashes,
+        // and the special "root_parent" below.
+        0u8.hash(&mut hasher);
+        parent_hash.hash(&mut hasher);
+
+        let DisambiguatedDefPathData { ref data, disambiguator } = self.disambiguated_data;
+
+        ::std::mem::discriminant(data).hash(&mut hasher);
+        if let Some(name) = data.get_opt_name() {
+            // Get a stable hash by considering the symbol chars rather than
+            // the symbol index.
+            name.as_str().hash(&mut hasher);
+        }
+
+        disambiguator.hash(&mut hasher);
+
+        DefPathHash(hasher.finish())
+    }
+
+    fn root_parent_stable_hash(
+        crate_name: &str,
+        crate_disambiguator: CrateDisambiguator,
+    ) -> DefPathHash {
+        let mut hasher = StableHasher::new();
+        // Disambiguate this from a regular `DefPath` hash; see `compute_stable_hash()` above.
+        1u8.hash(&mut hasher);
+        crate_name.hash(&mut hasher);
+        crate_disambiguator.hash(&mut hasher);
+        DefPathHash(hasher.finish())
+    }
+}
+
+/// A pair of `DefPathData` and an integer disambiguator. The integer is
+/// normally `0`, but in the event that there are multiple defs with the
+/// same `parent` and `data`, we use this field to disambiguate
+/// between them. This introduces some artificial ordering dependency
+/// but means that if you have, e.g., two impls for the same type in
+/// the same module, they do get distinct `DefId`s.
+#[derive(Copy, Clone, PartialEq, Debug, Encodable, Decodable)]
+pub struct DisambiguatedDefPathData {
+    pub data: DefPathData,
+    pub disambiguator: u32,
+}
+
+#[derive(Clone, Debug, Encodable, Decodable)]
+pub struct DefPath {
+    /// The path leading from the crate root to the item.
+    pub data: Vec<DisambiguatedDefPathData>,
+
+    /// The crate root this path is relative to.
+    pub krate: CrateNum,
+}
+
+impl DefPath {
+    pub fn is_local(&self) -> bool {
+        self.krate == LOCAL_CRATE
+    }
+
+    pub fn make<FN>(krate: CrateNum, start_index: DefIndex, mut get_key: FN) -> DefPath
+    where
+        FN: FnMut(DefIndex) -> DefKey,
+    {
+        let mut data = vec![];
+        let mut index = Some(start_index);
+        loop {
+            debug!("DefPath::make: krate={:?} index={:?}", krate, index);
+            let p = index.unwrap();
+            let key = get_key(p);
+            debug!("DefPath::make: key={:?}", key);
+            match key.disambiguated_data.data {
+                DefPathData::CrateRoot => {
+                    assert!(key.parent.is_none());
+                    break;
+                }
+                _ => {
+                    data.push(key.disambiguated_data);
+                    index = key.parent;
+                }
+            }
+        }
+        data.reverse();
+        DefPath { data, krate }
+    }
+
+    /// Returns a string representation of the `DefPath` without
+    /// the crate-prefix. This method is useful if you don't have
+    /// a `TyCtxt` available.
+    pub fn to_string_no_crate(&self) -> String {
+        let mut s = String::with_capacity(self.data.len() * 16);
+
+        for component in &self.data {
+            write!(s, "::{}[{}]", component.data.as_symbol(), component.disambiguator).unwrap();
+        }
+
+        s
+    }
+
+    /// Returns a filename-friendly string for the `DefPath`, with the
+    /// crate-prefix.
+    pub fn to_string_friendly<F>(&self, crate_imported_name: F) -> String
+    where
+        F: FnOnce(CrateNum) -> Symbol,
+    {
+        let crate_name_str = crate_imported_name(self.krate).as_str();
+        let mut s = String::with_capacity(crate_name_str.len() + self.data.len() * 16);
+
+        write!(s, "::{}", crate_name_str).unwrap();
+
+        for component in &self.data {
+            if component.disambiguator == 0 {
+                write!(s, "::{}", component.data.as_symbol()).unwrap();
+            } else {
+                write!(s, "{}[{}]", component.data.as_symbol(), component.disambiguator).unwrap();
+            }
+        }
+
+        s
+    }
+
+    /// Returns a filename-friendly string of the `DefPath`, without
+    /// the crate-prefix. This method is useful if you don't have
+    /// a `TyCtxt` available.
+    pub fn to_filename_friendly_no_crate(&self) -> String {
+        let mut s = String::with_capacity(self.data.len() * 16);
+
+        let mut opt_delimiter = None;
+        for component in &self.data {
+            s.extend(opt_delimiter);
+            opt_delimiter = Some('-');
+            if component.disambiguator == 0 {
+                write!(s, "{}", component.data.as_symbol()).unwrap();
+            } else {
+                write!(s, "{}[{}]", component.data.as_symbol(), component.disambiguator).unwrap();
+            }
+        }
+        s
+    }
+}
+
+#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, Encodable, Decodable)]
+pub enum DefPathData {
+    // Root: these should only be used for the root nodes, because
+    // they are treated specially by the `def_path` function.
+    /// The crate root (marker).
+    CrateRoot,
+    // Catch-all for random `DefId` things like `DUMMY_NODE_ID`.
+    Misc,
+
+    // Different kinds of items and item-like things:
+    /// An impl.
+    Impl,
+    /// Something in the type namespace.
+    TypeNs(Symbol),
+    /// Something in the value namespace.
+    ValueNs(Symbol),
+    /// Something in the macro namespace.
+    MacroNs(Symbol),
+    /// Something in the lifetime namespace.
+    LifetimeNs(Symbol),
+    /// A closure expression.
+    ClosureExpr,
+
+    // Subportions of items:
+    /// Implicit constructor for a unit or tuple-like struct or enum variant.
+    Ctor,
+    /// A constant expression (see `{ast,hir}::AnonConst`).
+    AnonConst,
+    /// An `impl Trait` type node.
+    ImplTrait,
+}
+
+impl Definitions {
+    pub fn def_path_table(&self) -> &DefPathTable {
+        &self.table
+    }
+
+    /// Gets the number of definitions.
+    pub fn def_index_count(&self) -> usize {
+        self.table.index_to_key.len()
+    }
+
+    pub fn def_key(&self, id: LocalDefId) -> DefKey {
+        self.table.def_key(id.local_def_index)
+    }
+
+    #[inline(always)]
+    pub fn def_path_hash(&self, id: LocalDefId) -> DefPathHash {
+        self.table.def_path_hash(id.local_def_index)
+    }
+
+    /// Returns the path from the crate root to `index`. The root
+    /// nodes are not included in the path (i.e., this will be an
+    /// empty vector for the crate root). For an inlined item, this
+    /// will be the path of the item in the external crate (but the
+    /// path will begin with the path to the external crate).
+    pub fn def_path(&self, id: LocalDefId) -> DefPath {
+        DefPath::make(LOCAL_CRATE, id.local_def_index, |index| {
+            self.def_key(LocalDefId { local_def_index: index })
+        })
+    }
+
+    #[inline]
+    pub fn local_def_id_to_hir_id(&self, id: LocalDefId) -> hir::HirId {
+        self.def_id_to_hir_id[id].unwrap()
+    }
+
+    #[inline]
+    pub fn opt_local_def_id_to_hir_id(&self, id: LocalDefId) -> Option<hir::HirId> {
+        self.def_id_to_hir_id[id]
+    }
+
+    #[inline]
+    pub fn opt_hir_id_to_local_def_id(&self, hir_id: hir::HirId) -> Option<LocalDefId> {
+        self.hir_id_to_def_id.get(&hir_id).copied()
+    }
+
+    /// Adds a root definition (no parent) and a few other reserved definitions.
+    pub fn new(crate_name: &str, crate_disambiguator: CrateDisambiguator) -> Definitions {
+        let key = DefKey {
+            parent: None,
+            disambiguated_data: DisambiguatedDefPathData {
+                data: DefPathData::CrateRoot,
+                disambiguator: 0,
+            },
+        };
+
+        let parent_hash = DefKey::root_parent_stable_hash(crate_name, crate_disambiguator);
+        let def_path_hash = key.compute_stable_hash(parent_hash);
+
+        // Create the root definition.
+        let mut table = DefPathTable::default();
+        let root = LocalDefId { local_def_index: table.allocate(key, def_path_hash) };
+        assert_eq!(root.local_def_index, CRATE_DEF_INDEX);
+
+        Definitions {
+            table,
+            def_id_to_hir_id: Default::default(),
+            hir_id_to_def_id: Default::default(),
+            expansions_that_defined: Default::default(),
+            parent_modules_of_macro_defs: Default::default(),
+        }
+    }
+
+    /// Retrieves the root definition.
+    pub fn get_root_def(&self) -> LocalDefId {
+        LocalDefId { local_def_index: CRATE_DEF_INDEX }
+    }
+
+    /// Adds a definition with a parent definition.
+    pub fn create_def(
+        &mut self,
+        parent: LocalDefId,
+        data: DefPathData,
+        expn_id: ExpnId,
+        mut next_disambiguator: impl FnMut(LocalDefId, DefPathData) -> u32,
+    ) -> LocalDefId {
+        debug!("create_def(parent={:?}, data={:?}, expn_id={:?})", parent, data, expn_id);
+
+        // The root node must be created with `create_root_def()`.
+        assert!(data != DefPathData::CrateRoot);
+
+        let disambiguator = next_disambiguator(parent, data);
+        let key = DefKey {
+            parent: Some(parent.local_def_index),
+            disambiguated_data: DisambiguatedDefPathData { data, disambiguator },
+        };
+
+        let parent_hash = self.table.def_path_hash(parent.local_def_index);
+        let def_path_hash = key.compute_stable_hash(parent_hash);
+
+        debug!("create_def: after disambiguation, key = {:?}", key);
+
+        // Create the definition.
+        let def_id = LocalDefId { local_def_index: self.table.allocate(key, def_path_hash) };
+
+        if expn_id != ExpnId::root() {
+            self.expansions_that_defined.insert(def_id, expn_id);
+        }
+
+        def_id
+    }
+
+    /// Initializes the `LocalDefId` to `HirId` mapping once it has been generated during
+    /// AST to HIR lowering.
+    pub fn init_def_id_to_hir_id_mapping(
+        &mut self,
+        mapping: IndexVec<LocalDefId, Option<hir::HirId>>,
+    ) {
+        assert!(
+            self.def_id_to_hir_id.is_empty(),
+            "trying to initialize `LocalDefId` <-> `HirId` mappings twice"
+        );
+
+        // Build the reverse mapping of `def_id_to_hir_id`.
+        self.hir_id_to_def_id = mapping
+            .iter_enumerated()
+            .filter_map(|(def_id, hir_id)| hir_id.map(|hir_id| (hir_id, def_id)))
+            .collect();
+
+        self.def_id_to_hir_id = mapping;
+    }
+
+    pub fn expansion_that_defined(&self, id: LocalDefId) -> ExpnId {
+        self.expansions_that_defined.get(&id).copied().unwrap_or(ExpnId::root())
+    }
+
+    pub fn parent_module_of_macro_def(&self, expn_id: ExpnId) -> DefId {
+        self.parent_modules_of_macro_defs[&expn_id]
+    }
+
+    pub fn add_parent_module_of_macro_def(&mut self, expn_id: ExpnId, module: DefId) {
+        self.parent_modules_of_macro_defs.insert(expn_id, module);
+    }
+}
+
+impl DefPathData {
+    pub fn get_opt_name(&self) -> Option<Symbol> {
+        use self::DefPathData::*;
+        match *self {
+            TypeNs(name) | ValueNs(name) | MacroNs(name) | LifetimeNs(name) => Some(name),
+
+            Impl | CrateRoot | Misc | ClosureExpr | Ctor | AnonConst | ImplTrait => None,
+        }
+    }
+
+    pub fn as_symbol(&self) -> Symbol {
+        use self::DefPathData::*;
+        match *self {
+            TypeNs(name) | ValueNs(name) | MacroNs(name) | LifetimeNs(name) => name,
+            // Note that this does not show up in user print-outs.
+            CrateRoot => sym::double_braced_crate,
+            Impl => sym::double_braced_impl,
+            Misc => sym::double_braced_misc,
+            ClosureExpr => sym::double_braced_closure,
+            Ctor => sym::double_braced_constructor,
+            AnonConst => sym::double_braced_constant,
+            ImplTrait => sym::double_braced_opaque,
+        }
+    }
+
+    pub fn to_string(&self) -> String {
+        self.as_symbol().to_string()
+    }
+}