Auto merge of #39927 - nikomatsakis:incr-comp-skip-borrowck-2, r=eddyb

transition borrowck to visit all **bodies** and not item-likes

This is a better structure for incremental compilation and also more compatible with the eventual borrowck mir. It also fixes #38520 as a drive-by fix.

r? @eddyb

src/librustc/cfg/construct.rs

@@ -32,7 +32,7 @@ struct LoopScope {
 }
 
 pub fn construct<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
-                           body: &hir::Expr) -> CFG {
+                           body: &hir::Body) -> CFG {
     let mut graph = graph::Graph::new();
     let entry = graph.add_node(CFGNodeData::Entry);
 
@@ -43,26 +43,18 @@ pub fn construct<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
     let fn_exit = graph.add_node(CFGNodeData::Exit);
     let body_exit;
 
-    // Find the function this expression is from.
-    let mut node_id = body.id;
-    loop {
-        let node = tcx.hir.get(node_id);
-        if hir::map::blocks::FnLikeNode::from_node(node).is_some() {
-            break;
-        }
-        let parent = tcx.hir.get_parent_node(node_id);
-        assert!(node_id != parent);
-        node_id = parent;
-    }
+    // Find the tables for this body.
+    let owner_def_id = tcx.hir.local_def_id(tcx.hir.body_owner(body.id()));
+    let tables = tcx.item_tables(owner_def_id);
 
     let mut cfg_builder = CFGBuilder {
         tcx: tcx,
-        tables: tcx.item_tables(tcx.hir.local_def_id(node_id)),
+        tables: tables,
         graph: graph,
         fn_exit: fn_exit,
         loop_scopes: Vec::new()
     };
-    body_exit = cfg_builder.expr(body, entry);
+    body_exit = cfg_builder.expr(&body.value, entry);
     cfg_builder.add_contained_edge(body_exit, fn_exit);
     let CFGBuilder {graph, ..} = cfg_builder;
     CFG {graph: graph,

src/librustc/cfg/mod.rs

@@ -59,7 +59,7 @@ pub type CFGEdge = graph::Edge<CFGEdgeData>;
 
 impl CFG {
     pub fn new<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
-                         body: &hir::Expr) -> CFG {
+                         body: &hir::Body) -> CFG {
         construct::construct(tcx, body)
     }
 

src/librustc/dep_graph/dep_node.rs

@@ -89,8 +89,10 @@ pub enum DepNode<D: Clone + Debug> {
 
     // Represents the MIR for a fn; also used as the task node for
     // things read/modify that MIR.
+    MirKrate,
     Mir(D),
 
+    BorrowCheckKrate,
     BorrowCheck(D),
     RvalueCheck(D),
     Reachability,
@@ -114,6 +116,7 @@ pub enum DepNode<D: Clone + Debug> {
     SizedConstraint(D),
     AssociatedItemDefIds(D),
     InherentImpls(D),
+    TypeckBodiesKrate,
     TypeckTables(D),
     UsedTraitImports(D),
     MonomorphicConstEval(D),
@@ -209,6 +212,9 @@ impl<D: Clone + Debug> DepNode<D> {
 
         match *self {
             Krate => Some(Krate),
+            BorrowCheckKrate => Some(BorrowCheckKrate),
+            MirKrate => Some(MirKrate),
+            TypeckBodiesKrate => Some(TypeckBodiesKrate),
             CollectLanguageItems => Some(CollectLanguageItems),
             CheckStaticRecursion => Some(CheckStaticRecursion),
             ResolveLifetimes => Some(ResolveLifetimes),

src/librustc/dep_graph/mod.rs

@@ -25,5 +25,6 @@ pub use self::dep_node::WorkProductId;
 pub use self::graph::DepGraph;
 pub use self::graph::WorkProduct;
 pub use self::query::DepGraphQuery;
+pub use self::visit::visit_all_bodies_in_krate;
 pub use self::visit::visit_all_item_likes_in_krate;
 pub use self::raii::DepTask;

src/librustc/dep_graph/visit.rs

@@ -74,3 +74,13 @@ pub fn visit_all_item_likes_in_krate<'a, 'tcx, V, F>(tcx: TyCtxt<'a, 'tcx, 'tcx>
     };
     krate.visit_all_item_likes(&mut tracking_visitor)
 }
+
+pub fn visit_all_bodies_in_krate<'a, 'tcx, C>(tcx: TyCtxt<'a, 'tcx, 'tcx>, callback: C)
+    where C: Fn(/* body_owner */ DefId, /* body id */ hir::BodyId),
+{
+    let krate = tcx.hir.krate();
+    for &body_id in &krate.body_ids {
+        let body_owner_def_id = tcx.hir.body_owner_def_id(body_id);
+        callback(body_owner_def_id, body_id);
+    }
+}

src/librustc/hir/lowering.rs

@@ -46,7 +46,7 @@ use hir::map::definitions::DefPathData;
 use hir::def_id::{DefIndex, DefId};
 use hir::def::{Def, PathResolution};
 use session::Session;
-use util::nodemap::{DefIdMap, NodeMap, FxHashMap};
+use util::nodemap::{DefIdMap, NodeMap};
 
 use std::collections::BTreeMap;
 use std::iter;
@@ -78,7 +78,7 @@ pub struct LoweringContext<'a> {
 
     trait_items: BTreeMap<hir::TraitItemId, hir::TraitItem>,
     impl_items: BTreeMap<hir::ImplItemId, hir::ImplItem>,
-    bodies: FxHashMap<hir::BodyId, hir::Body>,
+    bodies: BTreeMap<hir::BodyId, hir::Body>,
 
     trait_impls: BTreeMap<DefId, Vec<NodeId>>,
     trait_default_impl: BTreeMap<DefId, NodeId>,
@@ -118,7 +118,7 @@ pub fn lower_crate(sess: &Session,
         items: BTreeMap::new(),
         trait_items: BTreeMap::new(),
         impl_items: BTreeMap::new(),
-        bodies: FxHashMap(),
+        bodies: BTreeMap::new(),
         trait_impls: BTreeMap::new(),
         trait_default_impl: BTreeMap::new(),
         loop_scopes: Vec::new(),
@@ -196,6 +196,7 @@ impl<'a> LoweringContext<'a> {
         let module = self.lower_mod(&c.module);
         let attrs = self.lower_attrs(&c.attrs);
         let exported_macros = c.exported_macros.iter().map(|m| self.lower_macro_def(m)).collect();
+        let body_ids = body_ids(&self.bodies);
 
         hir::Crate {
             module: module,
@@ -206,6 +207,7 @@ impl<'a> LoweringContext<'a> {
             trait_items: self.trait_items,
             impl_items: self.impl_items,
             bodies: self.bodies,
+            body_ids: body_ids,
             trait_impls: self.trait_impls,
             trait_default_impl: self.trait_default_impl,
         }
@@ -2524,3 +2526,11 @@ impl<'a> LoweringContext<'a> {
         }
     }
 }
+
+fn body_ids(bodies: &BTreeMap<hir::BodyId, hir::Body>) -> Vec<hir::BodyId> {
+    // Sorting by span ensures that we get things in order within a
+    // file, and also puts the files in a sensible order.
+    let mut body_ids: Vec<_> = bodies.keys().cloned().collect();
+    body_ids.sort_by_key(|b| bodies[b].value.span);
+    body_ids
+}

src/librustc/hir/map/def_collector.rs

@@ -259,6 +259,7 @@ impl<'a> visit::Visitor<'a> for DefCollector<'a> {
             TyKind::ImplTrait(..) => {
                 self.create_def(ty.id, DefPathData::ImplTrait);
             }
+            TyKind::Typeof(ref expr) => self.visit_ast_const_integer(expr),
             _ => {}
         }
         visit::walk_ty(self, ty);

src/librustc/hir/map/definitions.rs

@@ -260,7 +260,9 @@ pub enum DefPathData {
     /// Pattern binding
     Binding(InternedString),
     /// An `impl Trait` type node.
-    ImplTrait
+    ImplTrait,
+    /// A `typeof` type node.
+    Typeof,
 }
 
 impl Definitions {
@@ -387,7 +389,8 @@ impl DefPathData {
             ClosureExpr |
             StructCtor |
             Initializer |
-            ImplTrait => None
+            ImplTrait |
+            Typeof => None
         }
     }
 
@@ -415,6 +418,7 @@ impl DefPathData {
             StructCtor => "{{constructor}}",
             Initializer => "{{initializer}}",
             ImplTrait => "{{impl-Trait}}",
+            Typeof => "{{typeof}}",
         };
 
         Symbol::intern(s).as_str()

src/librustc/hir/map/mod.rs

@@ -168,43 +168,48 @@ impl<'hir> MapEntry<'hir> {
         })
     }
 
-    fn is_body_owner(self, node_id: NodeId) -> bool {
+    fn associated_body(self) -> Option<BodyId> {
         match self {
             EntryItem(_, item) => {
                 match item.node {
                     ItemConst(_, body) |
                     ItemStatic(.., body) |
-                    ItemFn(_, _, _, _, _, body) => body.node_id == node_id,
-                    _ => false
+                    ItemFn(_, _, _, _, _, body) => Some(body),
+                    _ => None,
                 }
             }
 
             EntryTraitItem(_, item) => {
                 match item.node {
                     TraitItemKind::Const(_, Some(body)) |
-                    TraitItemKind::Method(_, TraitMethod::Provided(body)) => {
-                        body.node_id == node_id
-                    }
-                    _ => false
+                    TraitItemKind::Method(_, TraitMethod::Provided(body)) => Some(body),
+                    _ => None
                 }
             }
 
             EntryImplItem(_, item) => {
                 match item.node {
                     ImplItemKind::Const(_, body) |
-                    ImplItemKind::Method(_, body) => body.node_id == node_id,
-                    _ => false
+                    ImplItemKind::Method(_, body) => Some(body),
+                    _ => None,
                 }
             }
 
             EntryExpr(_, expr) => {
                 match expr.node {
-                    ExprClosure(.., body, _) => body.node_id == node_id,
-                    _ => false
+                    ExprClosure(.., body, _) => Some(body),
+                    _ => None,
                 }
             }
 
-            _ => false
+            _ => None
+        }
+    }
+
+    fn is_body_owner(self, node_id: NodeId) -> bool {
+        match self.associated_body() {
+            Some(b) => b.node_id == node_id,
+            None => false,
         }
     }
 }

src/librustc/hir/mod.rs

@@ -31,7 +31,7 @@ pub use self::PathParameters::*;
 
 use hir::def::Def;
 use hir::def_id::DefId;
-use util::nodemap::{NodeMap, FxHashMap, FxHashSet};
+use util::nodemap::{NodeMap, FxHashSet};
 
 use syntax_pos::{Span, ExpnId, DUMMY_SP};
 use syntax::codemap::{self, Spanned};
@@ -409,10 +409,15 @@ pub struct Crate {
 
     pub trait_items: BTreeMap<TraitItemId, TraitItem>,
     pub impl_items: BTreeMap<ImplItemId, ImplItem>,
-    pub bodies: FxHashMap<BodyId, Body>,
-
+    pub bodies: BTreeMap<BodyId, Body>,
     pub trait_impls: BTreeMap<DefId, Vec<NodeId>>,
     pub trait_default_impl: BTreeMap<DefId, NodeId>,
+
+    /// A list of the body ids written out in the order in which they
+    /// appear in the crate. If you're going to process all the bodies
+    /// in the crate, you should iterate over this list rather than the keys
+    /// of bodies.
+    pub body_ids: Vec<BodyId>,
 }
 
 impl Crate {

src/librustc/middle/free_region.rs

@@ -19,7 +19,7 @@ use ty::{self, TyCtxt, FreeRegion, Region};
 use ty::wf::ImpliedBound;
 use rustc_data_structures::transitive_relation::TransitiveRelation;
 
-#[derive(Clone)]
+#[derive(Clone, RustcEncodable, RustcDecodable)]
 pub struct FreeRegionMap {
     // Stores the relation `a < b`, where `a` and `b` are regions.
     relation: TransitiveRelation<Region>
@@ -30,6 +30,10 @@ impl FreeRegionMap {
         FreeRegionMap { relation: TransitiveRelation::new() }
     }
 
+    pub fn is_empty(&self) -> bool {
+        self.relation.is_empty()
+    }
+
     pub fn relate_free_regions_from_implied_bounds<'tcx>(&mut self,
                                                         implied_bounds: &[ImpliedBound<'tcx>])
     {

src/librustc/ty/context.rs

@@ -248,6 +248,11 @@ pub struct TypeckTables<'tcx> {
     /// If any errors occurred while type-checking this body,
     /// this field will be set to `true`.
     pub tainted_by_errors: bool,
+
+    /// Stores the free-region relationships that were deduced from
+    /// its where clauses and parameter types. These are then
+    /// read-again by borrowck.
+    pub free_region_map: FreeRegionMap,
 }
 
 impl<'tcx> TypeckTables<'tcx> {
@@ -267,6 +272,7 @@ impl<'tcx> TypeckTables<'tcx> {
             lints: lint::LintTable::new(),
             used_trait_imports: DefIdSet(),
             tainted_by_errors: false,
+            free_region_map: FreeRegionMap::new(),
         }
     }
 
@@ -414,13 +420,6 @@ pub struct GlobalCtxt<'tcx> {
 
     pub region_maps: RegionMaps,
 
-    // For each fn declared in the local crate, type check stores the
-    // free-region relationships that were deduced from its where
-    // clauses and parameter types. These are then read-again by
-    // borrowck. (They are not used during trans, and hence are not
-    // serialized or needed for cross-crate fns.)
-    free_region_maps: RefCell<NodeMap<FreeRegionMap>>,
-
     pub hir: hir_map::Map<'tcx>,
     pub maps: maps::Maps<'tcx>,
 
@@ -645,16 +644,6 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
         interned
     }
 
-    pub fn store_free_region_map(self, id: NodeId, map: FreeRegionMap) {
-        if self.free_region_maps.borrow_mut().insert(id, map).is_some() {
-            bug!("Tried to overwrite interned FreeRegionMap for NodeId {:?}", id)
-        }
-    }
-
-    pub fn free_region_map(self, id: NodeId) -> FreeRegionMap {
-        self.free_region_maps.borrow()[&id].clone()
-    }
-
     pub fn lift<T: ?Sized + Lift<'tcx>>(self, value: &T) -> Option<T::Lifted> {
         value.lift_to_tcx(self)
     }
@@ -707,7 +696,6 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
             types: common_types,
             named_region_map: named_region_map,
             region_maps: region_maps,
-            free_region_maps: RefCell::new(FxHashMap()),
             variance_computed: Cell::new(false),
             trait_map: resolutions.trait_map,
             fulfilled_predicates: RefCell::new(fulfilled_predicates),

src/librustc/ty/item_path.rs

@@ -180,7 +180,8 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
             data @ DefPathData::MacroDef(..) |
             data @ DefPathData::ClosureExpr |
             data @ DefPathData::Binding(..) |
-            data @ DefPathData::ImplTrait => {
+            data @ DefPathData::ImplTrait |
+            data @ DefPathData::Typeof => {
                 let parent_def_id = self.parent_def_id(def_id).unwrap();
                 self.push_item_path(buffer, parent_def_id);
                 buffer.push(&data.as_interned_str());

src/librustc/ty/mod.rs

@@ -2602,6 +2602,17 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
         dep_graph::visit_all_item_likes_in_krate(self.global_tcx(), dep_node_fn, visitor);
     }
 
+    /// Invokes `callback` for each body in the krate. This will
+    /// create a read edge from `DepNode::Krate` to the current task;
+    /// it is meant to be run in the context of some global task like
+    /// `BorrowckCrate`. The callback would then create a task like
+    /// `BorrowckBody(DefId)` to process each individual item.
+    pub fn visit_all_bodies_in_krate<C>(self, callback: C)
+        where C: Fn(/* body_owner */ DefId, /* body id */ hir::BodyId),
+    {
+        dep_graph::visit_all_bodies_in_krate(self.global_tcx(), callback)
+    }
+
     /// Looks up the span of `impl_did` if the impl is local; otherwise returns `Err`
     /// with the name of the crate containing the impl.
     pub fn span_of_impl(self, impl_did: DefId) -> Result<Span, Symbol> {