1 files changed, 471 insertions, 0 deletions
diff --git a/src/tools/rust-analyzer/crates/hir-def/src/body.rs b/src/tools/rust-analyzer/crates/hir-def/src/body.rs
new file mode 100644
index 000000000..080a307b1
--- /dev/null
+++ b/src/tools/rust-analyzer/crates/hir-def/src/body.rs
@@ -0,0 +1,471 @@
+//! Defines `Body`: a lowered representation of bodies of functions, statics and
+//! consts.
+mod lower;
+#[cfg(test)]
+mod tests;
+pub mod scope;
+
+use std::{ops::Index, sync::Arc};
+
+use base_db::CrateId;
+use cfg::{CfgExpr, CfgOptions};
+use drop_bomb::DropBomb;
+use either::Either;
+use hir_expand::{hygiene::Hygiene, ExpandError, ExpandResult, HirFileId, InFile, MacroCallId};
+use la_arena::{Arena, ArenaMap};
+use limit::Limit;
+use profile::Count;
+use rustc_hash::FxHashMap;
+use syntax::{ast, AstPtr, SyntaxNodePtr};
+
+use crate::{
+    attr::{Attrs, RawAttrs},
+    db::DefDatabase,
+    expr::{dummy_expr_id, Expr, ExprId, Label, LabelId, Pat, PatId},
+    item_scope::BuiltinShadowMode,
+    macro_id_to_def_id,
+    nameres::DefMap,
+    path::{ModPath, Path},
+    src::HasSource,
+    AsMacroCall, BlockId, DefWithBodyId, HasModule, LocalModuleId, Lookup, MacroId, ModuleId,
+    UnresolvedMacro,
+};
+
+pub use lower::LowerCtx;
+
+/// A subset of Expander that only deals with cfg attributes. We only need it to
+/// avoid cyclic queries in crate def map during enum processing.
+#[derive(Debug)]
+pub(crate) struct CfgExpander {
+    cfg_options: CfgOptions,
+    hygiene: Hygiene,
+    krate: CrateId,
+}
+
+#[derive(Debug)]
+pub struct Expander {
+    cfg_expander: CfgExpander,
+    def_map: Arc<DefMap>,
+    current_file_id: HirFileId,
+    module: LocalModuleId,
+    recursion_limit: usize,
+}
+
+impl CfgExpander {
+    pub(crate) fn new(
+        db: &dyn DefDatabase,
+        current_file_id: HirFileId,
+        krate: CrateId,
+    ) -> CfgExpander {
+        let hygiene = Hygiene::new(db.upcast(), current_file_id);
+        let cfg_options = db.crate_graph()[krate].cfg_options.clone();
+        CfgExpander { cfg_options, hygiene, krate }
+    }
+
+    pub(crate) fn parse_attrs(&self, db: &dyn DefDatabase, owner: &dyn ast::HasAttrs) -> Attrs {
+        RawAttrs::new(db, owner, &self.hygiene).filter(db, self.krate)
+    }
+
+    pub(crate) fn is_cfg_enabled(&self, db: &dyn DefDatabase, owner: &dyn ast::HasAttrs) -> bool {
+        let attrs = self.parse_attrs(db, owner);
+        attrs.is_cfg_enabled(&self.cfg_options)
+    }
+}
+
+impl Expander {
+    pub fn new(db: &dyn DefDatabase, current_file_id: HirFileId, module: ModuleId) -> Expander {
+        let cfg_expander = CfgExpander::new(db, current_file_id, module.krate);
+        let def_map = module.def_map(db);
+        Expander {
+            cfg_expander,
+            def_map,
+            current_file_id,
+            module: module.local_id,
+            recursion_limit: 0,
+        }
+    }
+
+    pub fn enter_expand<T: ast::AstNode>(
+        &mut self,
+        db: &dyn DefDatabase,
+        macro_call: ast::MacroCall,
+    ) -> Result<ExpandResult<Option<(Mark, T)>>, UnresolvedMacro> {
+        if self.recursion_limit(db).check(self.recursion_limit + 1).is_err() {
+            cov_mark::hit!(your_stack_belongs_to_me);
+            return Ok(ExpandResult::only_err(ExpandError::Other(
+                "reached recursion limit during macro expansion".into(),
+            )));
+        }
+
+        let macro_call = InFile::new(self.current_file_id, &macro_call);
+
+        let resolver =
+            |path| self.resolve_path_as_macro(db, &path).map(|it| macro_id_to_def_id(db, it));
+
+        let mut err = None;
+        let call_id =
+            macro_call.as_call_id_with_errors(db, self.def_map.krate(), resolver, &mut |e| {
+                err.get_or_insert(e);
+            })?;
+        let call_id = match call_id {
+            Ok(it) => it,
+            Err(_) => {
+                return Ok(ExpandResult { value: None, err });
+            }
+        };
+
+        Ok(self.enter_expand_inner(db, call_id, err))
+    }
+
+    pub fn enter_expand_id<T: ast::AstNode>(
+        &mut self,
+        db: &dyn DefDatabase,
+        call_id: MacroCallId,
+    ) -> ExpandResult<Option<(Mark, T)>> {
+        self.enter_expand_inner(db, call_id, None)
+    }
+
+    fn enter_expand_inner<T: ast::AstNode>(
+        &mut self,
+        db: &dyn DefDatabase,
+        call_id: MacroCallId,
+        mut err: Option<ExpandError>,
+    ) -> ExpandResult<Option<(Mark, T)>> {
+        if err.is_none() {
+            err = db.macro_expand_error(call_id);
+        }
+
+        let file_id = call_id.as_file();
+
+        let raw_node = match db.parse_or_expand(file_id) {
+            Some(it) => it,
+            None => {
+                // Only `None` if the macro expansion produced no usable AST.
+                if err.is_none() {
+                    tracing::warn!("no error despite `parse_or_expand` failing");
+                }
+
+                return ExpandResult::only_err(err.unwrap_or_else(|| {
+                    ExpandError::Other("failed to parse macro invocation".into())
+                }));
+            }
+        };
+
+        let node = match T::cast(raw_node) {
+            Some(it) => it,
+            None => {
+                // This can happen without being an error, so only forward previous errors.
+                return ExpandResult { value: None, err };
+            }
+        };
+
+        tracing::debug!("macro expansion {:#?}", node.syntax());
+
+        self.recursion_limit += 1;
+        let mark =
+            Mark { file_id: self.current_file_id, bomb: DropBomb::new("expansion mark dropped") };
+        self.cfg_expander.hygiene = Hygiene::new(db.upcast(), file_id);
+        self.current_file_id = file_id;
+
+        ExpandResult { value: Some((mark, node)), err }
+    }
+
+    pub fn exit(&mut self, db: &dyn DefDatabase, mut mark: Mark) {
+        self.cfg_expander.hygiene = Hygiene::new(db.upcast(), mark.file_id);
+        self.current_file_id = mark.file_id;
+        self.recursion_limit -= 1;
+        mark.bomb.defuse();
+    }
+
+    pub(crate) fn to_source<T>(&self, value: T) -> InFile<T> {
+        InFile { file_id: self.current_file_id, value }
+    }
+
+    pub(crate) fn parse_attrs(&self, db: &dyn DefDatabase, owner: &dyn ast::HasAttrs) -> Attrs {
+        self.cfg_expander.parse_attrs(db, owner)
+    }
+
+    pub(crate) fn cfg_options(&self) -> &CfgOptions {
+        &self.cfg_expander.cfg_options
+    }
+
+    pub fn current_file_id(&self) -> HirFileId {
+        self.current_file_id
+    }
+
+    fn parse_path(&mut self, db: &dyn DefDatabase, path: ast::Path) -> Option<Path> {
+        let ctx = LowerCtx::with_hygiene(db, &self.cfg_expander.hygiene);
+        Path::from_src(path, &ctx)
+    }
+
+    fn resolve_path_as_macro(&self, db: &dyn DefDatabase, path: &ModPath) -> Option<MacroId> {
+        self.def_map.resolve_path(db, self.module, path, BuiltinShadowMode::Other).0.take_macros()
+    }
+
+    fn recursion_limit(&self, db: &dyn DefDatabase) -> Limit {
+        let limit = db.crate_limits(self.cfg_expander.krate).recursion_limit as _;
+
+        #[cfg(not(test))]
+        return Limit::new(limit);
+
+        // Without this, `body::tests::your_stack_belongs_to_me` stack-overflows in debug
+        #[cfg(test)]
+        return Limit::new(std::cmp::min(32, limit));
+    }
+}
+
+#[derive(Debug)]
+pub struct Mark {
+    file_id: HirFileId,
+    bomb: DropBomb,
+}
+
+/// The body of an item (function, const etc.).
+#[derive(Debug, Eq, PartialEq)]
+pub struct Body {
+    pub exprs: Arena<Expr>,
+    pub pats: Arena<Pat>,
+    pub or_pats: FxHashMap<PatId, Arc<[PatId]>>,
+    pub labels: Arena<Label>,
+    /// The patterns for the function's parameters. While the parameter types are
+    /// part of the function signature, the patterns are not (they don't change
+    /// the external type of the function).
+    ///
+    /// If this `Body` is for the body of a constant, this will just be
+    /// empty.
+    pub params: Vec<PatId>,
+    /// The `ExprId` of the actual body expression.
+    pub body_expr: ExprId,
+    /// Block expressions in this body that may contain inner items.
+    block_scopes: Vec<BlockId>,
+    _c: Count<Self>,
+}
+
+pub type ExprPtr = AstPtr<ast::Expr>;
+pub type ExprSource = InFile<ExprPtr>;
+
+pub type PatPtr = Either<AstPtr<ast::Pat>, AstPtr<ast::SelfParam>>;
+pub type PatSource = InFile<PatPtr>;
+
+pub type LabelPtr = AstPtr<ast::Label>;
+pub type LabelSource = InFile<LabelPtr>;
+/// An item body together with the mapping from syntax nodes to HIR expression
+/// IDs. This is needed to go from e.g. a position in a file to the HIR
+/// expression containing it; but for type inference etc., we want to operate on
+/// a structure that is agnostic to the actual positions of expressions in the
+/// file, so that we don't recompute types whenever some whitespace is typed.
+///
+/// One complication here is that, due to macro expansion, a single `Body` might
+/// be spread across several files. So, for each ExprId and PatId, we record
+/// both the HirFileId and the position inside the file. However, we only store
+/// AST -> ExprId mapping for non-macro files, as it is not clear how to handle
+/// this properly for macros.
+#[derive(Default, Debug, Eq, PartialEq)]
+pub struct BodySourceMap {
+    expr_map: FxHashMap<ExprSource, ExprId>,
+    expr_map_back: ArenaMap<ExprId, Result<ExprSource, SyntheticSyntax>>,
+
+    pat_map: FxHashMap<PatSource, PatId>,
+    pat_map_back: ArenaMap<PatId, Result<PatSource, SyntheticSyntax>>,
+
+    label_map: FxHashMap<LabelSource, LabelId>,
+    label_map_back: ArenaMap<LabelId, LabelSource>,
+
+    /// We don't create explicit nodes for record fields (`S { record_field: 92 }`).
+    /// Instead, we use id of expression (`92`) to identify the field.
+    field_map: FxHashMap<InFile<AstPtr<ast::RecordExprField>>, ExprId>,
+    field_map_back: FxHashMap<ExprId, InFile<AstPtr<ast::RecordExprField>>>,
+
+    expansions: FxHashMap<InFile<AstPtr<ast::MacroCall>>, HirFileId>,
+
+    /// Diagnostics accumulated during body lowering. These contain `AstPtr`s and so are stored in
+    /// the source map (since they're just as volatile).
+    diagnostics: Vec<BodyDiagnostic>,
+}
+
+#[derive(Default, Debug, Eq, PartialEq, Clone, Copy)]
+pub struct SyntheticSyntax;
+
+#[derive(Debug, Eq, PartialEq)]
+pub enum BodyDiagnostic {
+    InactiveCode { node: InFile<SyntaxNodePtr>, cfg: CfgExpr, opts: CfgOptions },
+    MacroError { node: InFile<AstPtr<ast::MacroCall>>, message: String },
+    UnresolvedProcMacro { node: InFile<AstPtr<ast::MacroCall>>, krate: CrateId },
+    UnresolvedMacroCall { node: InFile<AstPtr<ast::MacroCall>>, path: ModPath },
+}
+
+impl Body {
+    pub(crate) fn body_with_source_map_query(
+        db: &dyn DefDatabase,
+        def: DefWithBodyId,
+    ) -> (Arc<Body>, Arc<BodySourceMap>) {
+        let _p = profile::span("body_with_source_map_query");
+        let mut params = None;
+
+        let (file_id, module, body) = match def {
+            DefWithBodyId::FunctionId(f) => {
+                let f = f.lookup(db);
+                let src = f.source(db);
+                params = src.value.param_list();
+                (src.file_id, f.module(db), src.value.body().map(ast::Expr::from))
+            }
+            DefWithBodyId::ConstId(c) => {
+                let c = c.lookup(db);
+                let src = c.source(db);
+                (src.file_id, c.module(db), src.value.body())
+            }
+            DefWithBodyId::StaticId(s) => {
+                let s = s.lookup(db);
+                let src = s.source(db);
+                (src.file_id, s.module(db), src.value.body())
+            }
+        };
+        let expander = Expander::new(db, file_id, module);
+        let (mut body, source_map) = Body::new(db, expander, params, body);
+        body.shrink_to_fit();
+        (Arc::new(body), Arc::new(source_map))
+    }
+
+    pub(crate) fn body_query(db: &dyn DefDatabase, def: DefWithBodyId) -> Arc<Body> {
+        db.body_with_source_map(def).0
+    }
+
+    /// Returns an iterator over all block expressions in this body that define inner items.
+    pub fn blocks<'a>(
+        &'a self,
+        db: &'a dyn DefDatabase,
+    ) -> impl Iterator<Item = (BlockId, Arc<DefMap>)> + '_ {
+        self.block_scopes
+            .iter()
+            .map(move |&block| (block, db.block_def_map(block).expect("block ID without DefMap")))
+    }
+
+    pub fn pattern_representative(&self, pat: PatId) -> PatId {
+        self.or_pats.get(&pat).and_then(|pats| pats.first().copied()).unwrap_or(pat)
+    }
+
+    /// Retrieves all ident patterns this pattern shares the ident with.
+    pub fn ident_patterns_for<'slf>(&'slf self, pat: &'slf PatId) -> &'slf [PatId] {
+        match self.or_pats.get(pat) {
+            Some(pats) => &**pats,
+            None => std::slice::from_ref(pat),
+        }
+    }
+
+    fn new(
+        db: &dyn DefDatabase,
+        expander: Expander,
+        params: Option<ast::ParamList>,
+        body: Option<ast::Expr>,
+    ) -> (Body, BodySourceMap) {
+        lower::lower(db, expander, params, body)
+    }
+
+    fn shrink_to_fit(&mut self) {
+        let Self { _c: _, body_expr: _, block_scopes, or_pats, exprs, labels, params, pats } = self;
+        block_scopes.shrink_to_fit();
+        or_pats.shrink_to_fit();
+        exprs.shrink_to_fit();
+        labels.shrink_to_fit();
+        params.shrink_to_fit();
+        pats.shrink_to_fit();
+    }
+}
+
+impl Default for Body {
+    fn default() -> Self {
+        Self {
+            body_expr: dummy_expr_id(),
+            exprs: Default::default(),
+            pats: Default::default(),
+            or_pats: Default::default(),
+            labels: Default::default(),
+            params: Default::default(),
+            block_scopes: Default::default(),
+            _c: Default::default(),
+        }
+    }
+}
+
+impl Index<ExprId> for Body {
+    type Output = Expr;
+
+    fn index(&self, expr: ExprId) -> &Expr {
+        &self.exprs[expr]
+    }
+}
+
+impl Index<PatId> for Body {
+    type Output = Pat;
+
+    fn index(&self, pat: PatId) -> &Pat {
+        &self.pats[pat]
+    }
+}
+
+impl Index<LabelId> for Body {
+    type Output = Label;
+
+    fn index(&self, label: LabelId) -> &Label {
+        &self.labels[label]
+    }
+}
+
+// FIXME: Change `node_` prefix to something more reasonable.
+// Perhaps `expr_syntax` and `expr_id`?
+impl BodySourceMap {
+    pub fn expr_syntax(&self, expr: ExprId) -> Result<ExprSource, SyntheticSyntax> {
+        self.expr_map_back[expr].clone()
+    }
+
+    pub fn node_expr(&self, node: InFile<&ast::Expr>) -> Option<ExprId> {
+        let src = node.map(AstPtr::new);
+        self.expr_map.get(&src).cloned()
+    }
+
+    pub fn node_macro_file(&self, node: InFile<&ast::MacroCall>) -> Option<HirFileId> {
+        let src = node.map(AstPtr::new);
+        self.expansions.get(&src).cloned()
+    }
+
+    pub fn pat_syntax(&self, pat: PatId) -> Result<PatSource, SyntheticSyntax> {
+        self.pat_map_back[pat].clone()
+    }
+
+    pub fn node_pat(&self, node: InFile<&ast::Pat>) -> Option<PatId> {
+        let src = node.map(|it| Either::Left(AstPtr::new(it)));
+        self.pat_map.get(&src).cloned()
+    }
+
+    pub fn node_self_param(&self, node: InFile<&ast::SelfParam>) -> Option<PatId> {
+        let src = node.map(|it| Either::Right(AstPtr::new(it)));
+        self.pat_map.get(&src).cloned()
+    }
+
+    pub fn label_syntax(&self, label: LabelId) -> LabelSource {
+        self.label_map_back[label].clone()
+    }
+
+    pub fn node_label(&self, node: InFile<&ast::Label>) -> Option<LabelId> {
+        let src = node.map(AstPtr::new);
+        self.label_map.get(&src).cloned()
+    }
+
+    pub fn field_syntax(&self, expr: ExprId) -> InFile<AstPtr<ast::RecordExprField>> {
+        self.field_map_back[&expr].clone()
+    }
+    pub fn node_field(&self, node: InFile<&ast::RecordExprField>) -> Option<ExprId> {
+        let src = node.map(AstPtr::new);
+        self.field_map.get(&src).cloned()
+    }
+
+    pub fn macro_expansion_expr(&self, node: InFile<&ast::MacroExpr>) -> Option<ExprId> {
+        let src = node.map(AstPtr::new).map(AstPtr::upcast::<ast::MacroExpr>).map(AstPtr::upcast);
+        self.expr_map.get(&src).copied()
+    }
+
+    /// Get a reference to the body source map's diagnostics.
+    pub fn diagnostics(&self) -> &[BodyDiagnostic] {
+        &self.diagnostics
+    }
+}