Rollup merge of rust-lang#40683 - nikomatsakis:incr-comp-coerce-unsized-info, r=eddyb

on-demand-ify `custom_coerce_unsized_kind` and `inherent-impls`

This "on-demand" task both checks for errors and computes the custom unsized kind, if any. This task is only defined on impls of `CoerceUnsized`; invoking it on any other kind of impl results in a bug. This is just to avoid having an `Option`, could easily be changed.

r? @eddyb

Author: alexcrichton

src/librustc/dep_graph/dep_node.rs

@@ -75,7 +75,6 @@ pub enum DepNode<D: Clone + Debug> {
     CoherenceCheckImpl(D),
     CoherenceOverlapCheck(D),
     CoherenceOverlapCheckSpecial(D),
-    CoherenceOverlapInherentCheck(D),
     CoherenceOrphanCheck(D),
     Variance,
     WfCheck(D),
@@ -252,7 +251,6 @@ impl<D: Clone + Debug> DepNode<D> {
             CoherenceCheckImpl(ref d) => op(d).map(CoherenceCheckImpl),
             CoherenceOverlapCheck(ref d) => op(d).map(CoherenceOverlapCheck),
             CoherenceOverlapCheckSpecial(ref d) => op(d).map(CoherenceOverlapCheckSpecial),
-            CoherenceOverlapInherentCheck(ref d) => op(d).map(CoherenceOverlapInherentCheck),
             CoherenceOrphanCheck(ref d) => op(d).map(CoherenceOrphanCheck),
             WfCheck(ref d) => op(d).map(WfCheck),
             TypeckItemType(ref d) => op(d).map(TypeckItemType),

src/librustc/dep_graph/dep_tracking_map.rs

@@ -81,21 +81,6 @@ impl<M: DepTrackingMapConfig> DepTrackingMap<M> {
     pub fn keys(&self) -> Vec<M::Key> {
         self.map.keys().cloned().collect()
     }
-
-    /// Append `elem` to the vector stored for `k`, creating a new vector if needed.
-    /// This is considered a write to `k`.
-    ///
-    /// NOTE: Caution is required when using this method. You should
-    /// be sure that nobody is **reading from the vector** while you
-    /// are writing to it. Eventually, it'd be nice to remove this.
-    pub fn push<E: Clone>(&mut self, k: M::Key, elem: E)
-        where M: DepTrackingMapConfig<Value=Vec<E>>
-    {
-        self.write(&k);
-        self.map.entry(k)
-                .or_insert(Vec::new())
-                .push(elem);
-    }
 }
 
 impl<M: DepTrackingMapConfig> MemoizationMap for RefCell<DepTrackingMap<M>> {

src/librustc/middle/cstore.rs

@@ -176,7 +176,6 @@ pub trait CrateStore {
     fn item_generics_cloned(&self, def: DefId) -> ty::Generics;
     fn item_attrs(&self, def_id: DefId) -> Vec<ast::Attribute>;
     fn fn_arg_names(&self, did: DefId) -> Vec<ast::Name>;
-    fn inherent_implementations_for_type(&self, def_id: DefId) -> Vec<DefId>;
 
     // trait info
     fn implementations_of_trait(&self, filter: Option<DefId>) -> Vec<DefId>;
@@ -310,7 +309,6 @@ impl CrateStore for DummyCrateStore {
         { bug!("item_generics_cloned") }
     fn item_attrs(&self, def_id: DefId) -> Vec<ast::Attribute> { bug!("item_attrs") }
     fn fn_arg_names(&self, did: DefId) -> Vec<ast::Name> { bug!("fn_arg_names") }
-    fn inherent_implementations_for_type(&self, def_id: DefId) -> Vec<DefId> { vec![] }
 
     // trait info
     fn implementations_of_trait(&self, filter: Option<DefId>) -> Vec<DefId> { vec![] }

src/librustc/ty/adjustment.rs

@@ -139,6 +139,21 @@ pub enum AutoBorrow<'tcx> {
     RawPtr(hir::Mutability),
 }
 
+/// Information for `CoerceUnsized` impls, storing information we
+/// have computed about the coercion.
+///
+/// This struct can be obtained via the `coerce_impl_info` query.
+/// Demanding this struct also has the side-effect of reporting errors
+/// for inappropriate impls.
+#[derive(Clone, Copy, RustcEncodable, RustcDecodable, Debug)]
+pub struct CoerceUnsizedInfo {
+    /// If this is a "custom coerce" impl, then what kind of custom
+    /// coercion is it? This applies to impls of `CoerceUnsized` for
+    /// structs, primarily, where we store a bit of info about which
+    /// fields need to be coerced.
+    pub custom_kind: Option<CustomCoerceUnsized>
+}
+
 #[derive(Clone, Copy, RustcEncodable, RustcDecodable, Debug)]
 pub enum CustomCoerceUnsized {
     /// Records the index of the field being coerced.

src/librustc/ty/maps.rs

@@ -13,7 +13,7 @@ use hir::def_id::{CrateNum, DefId, LOCAL_CRATE};
 use middle::const_val::ConstVal;
 use middle::privacy::AccessLevels;
 use mir;
-use ty::{self, Ty, TyCtxt};
+use ty::{self, CrateInherentImpls, Ty, TyCtxt};
 
 use rustc_data_structures::indexed_vec::IndexVec;
 use std::cell::{RefCell, RefMut};
@@ -177,9 +177,15 @@ impl<'tcx> QueryDescription for queries::coherent_trait<'tcx> {
     }
 }
 
-impl<'tcx> QueryDescription for queries::coherent_inherent_impls<'tcx> {
+impl<'tcx> QueryDescription for queries::crate_inherent_impls<'tcx> {
+    fn describe(_: TyCtxt, k: CrateNum) -> String {
+        format!("all inherent impls defined in crate `{:?}`", k)
+    }
+}
+
+impl<'tcx> QueryDescription for queries::crate_inherent_impls_overlap_check<'tcx> {
     fn describe(_: TyCtxt, _: CrateNum) -> String {
-        format!("coherence checking all inherent impls")
+        format!("check for overlap between inherent impls defined in this crate")
     }
 }
 
@@ -375,7 +381,7 @@ define_maps! { <'tcx>
     /// Maps a DefId of a type to a list of its inherent impls.
     /// Contains implementations of methods that are inherent to a type.
     /// Methods in these implementations don't need to be exported.
-    pub inherent_impls: InherentImpls(DefId) -> Vec<DefId>,
+    pub inherent_impls: InherentImpls(DefId) -> Rc<Vec<DefId>>,
 
     /// Maps from the def-id of a function/method or const/static
     /// to its MIR. Mutation is done at an item granularity to
@@ -400,14 +406,22 @@ define_maps! { <'tcx>
     pub closure_type: ItemSignature(DefId) -> ty::PolyFnSig<'tcx>,
 
     /// Caches CoerceUnsized kinds for impls on custom types.
-    pub custom_coerce_unsized_kind: ItemSignature(DefId)
-        -> ty::adjustment::CustomCoerceUnsized,
+    pub coerce_unsized_info: ItemSignature(DefId)
+        -> ty::adjustment::CoerceUnsizedInfo,
 
     pub typeck_tables: TypeckTables(DefId) -> &'tcx ty::TypeckTables<'tcx>,
 
     pub coherent_trait: coherent_trait_dep_node((CrateNum, DefId)) -> (),
 
-    pub coherent_inherent_impls: coherent_inherent_impls_dep_node(CrateNum) -> (),
+    /// Gets a complete map from all types to their inherent impls.
+    /// Not meant to be used directly outside of coherence.
+    /// (Defined only for LOCAL_CRATE)
+    pub crate_inherent_impls: crate_inherent_impls_dep_node(CrateNum) -> CrateInherentImpls,
+
+    /// Checks all types in the krate for overlap in their inherent impls. Reports errors.
+    /// Not meant to be used directly outside of coherence.
+    /// (Defined only for LOCAL_CRATE)
+    pub crate_inherent_impls_overlap_check: crate_inherent_impls_dep_node(CrateNum) -> (),
 
     /// Results of evaluating monomorphic constants embedded in
     /// other items, such as enum variant explicit discriminants.
@@ -423,7 +437,7 @@ fn coherent_trait_dep_node((_, def_id): (CrateNum, DefId)) -> DepNode<DefId> {
     DepNode::CoherenceCheckTrait(def_id)
 }
 
-fn coherent_inherent_impls_dep_node(_: CrateNum) -> DepNode<DefId> {
+fn crate_inherent_impls_dep_node(_: CrateNum) -> DepNode<DefId> {
     DepNode::Coherence
 }
 

src/librustc/ty/mod.rs

@@ -31,7 +31,7 @@ use ty::subst::{Subst, Substs};
 use ty::util::IntTypeExt;
 use ty::walk::TypeWalker;
 use util::common::MemoizationMap;
-use util::nodemap::{NodeSet, FxHashMap};
+use util::nodemap::{NodeSet, DefIdMap, FxHashMap};
 
 use serialize::{self, Encodable, Encoder};
 use std::borrow::Cow;
@@ -2057,8 +2057,8 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
         })
     }
 
-    pub fn custom_coerce_unsized_kind(self, did: DefId) -> adjustment::CustomCoerceUnsized {
-        queries::custom_coerce_unsized_kind::get(self, DUMMY_SP, did)
+    pub fn coerce_unsized_info(self, did: DefId) -> adjustment::CoerceUnsizedInfo {
+        queries::coerce_unsized_info::get(self, DUMMY_SP, did)
     }
 
     pub fn associated_item(self, def_id: DefId) -> AssociatedItem {
@@ -2348,34 +2348,6 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
         def.flags.get().intersects(TraitFlags::HAS_DEFAULT_IMPL)
     }
 
-    /// Populates the type context with all the inherent implementations for
-    /// the given type if necessary.
-    pub fn populate_inherent_implementations_for_type_if_necessary(self,
-                                                                   span: Span,
-                                                                   type_id: DefId) {
-        if type_id.is_local() {
-            // Make sure coherence of inherent impls ran already.
-            ty::queries::coherent_inherent_impls::force(self, span, LOCAL_CRATE);
-            return
-        }
-
-        // The type is not local, hence we are reading this out of
-        // metadata and don't need to track edges.
-        let _ignore = self.dep_graph.in_ignore();
-
-        if self.populated_external_types.borrow().contains(&type_id) {
-            return
-        }
-
-        debug!("populate_inherent_implementations_for_type_if_necessary: searching for {:?}",
-               type_id);
-
-        let inherent_impls = self.sess.cstore.inherent_implementations_for_type(type_id);
-
-        self.maps.inherent_impls.borrow_mut().insert(type_id, inherent_impls);
-        self.populated_external_types.borrow_mut().insert(type_id);
-    }
-
     /// Populates the type context with all the implementations for the given
     /// trait if necessary.
     pub fn populate_implementations_for_trait_if_necessary(self, trait_id: DefId) {
@@ -2640,3 +2612,16 @@ pub fn provide(providers: &mut ty::maps::Providers) {
         ..*providers
     };
 }
+
+
+/// A map for the local crate mapping each type to a vector of its
+/// inherent impls. This is not meant to be used outside of coherence;
+/// rather, you should request the vector for a specific type via
+/// `ty::queries::inherent_impls::get(def_id)` so as to minimize your
+/// dependencies (constructing this map requires touching the entire
+/// crate).
+#[derive(Clone, Debug)]
+pub struct CrateInherentImpls {
+    pub inherent_impls: DefIdMap<Rc<Vec<DefId>>>,
+}
+

src/librustc_metadata/cstore_impl.rs

@@ -88,9 +88,9 @@ provide! { <'tcx> tcx, def_id, cdata
     }
     associated_item => { cdata.get_associated_item(def_id.index) }
     impl_trait_ref => { cdata.get_impl_trait(def_id.index, tcx) }
-    custom_coerce_unsized_kind => {
-        cdata.get_custom_coerce_unsized_kind(def_id.index).unwrap_or_else(|| {
-            bug!("custom_coerce_unsized_kind: `{:?}` is missing its kind", def_id);
+    coerce_unsized_info => {
+        cdata.get_coerce_unsized_info(def_id.index).unwrap_or_else(|| {
+            bug!("coerce_unsized_info: `{:?}` is missing its info", def_id);
         })
     }
     mir => {
@@ -109,6 +109,7 @@ provide! { <'tcx> tcx, def_id, cdata
     typeck_tables => { cdata.item_body_tables(def_id.index, tcx) }
     closure_kind => { cdata.closure_kind(def_id.index) }
     closure_type => { cdata.closure_ty(def_id.index, tcx) }
+    inherent_impls => { Rc::new(cdata.get_inherent_implementations_for_type(def_id.index)) }
 }
 
 impl CrateStore for cstore::CStore {
@@ -162,12 +163,6 @@ impl CrateStore for cstore::CStore {
         self.get_crate_data(did.krate).get_fn_arg_names(did.index)
     }
 
-    fn inherent_implementations_for_type(&self, def_id: DefId) -> Vec<DefId>
-    {
-        self.dep_graph.read(DepNode::MetaData(def_id));
-        self.get_crate_data(def_id.krate).get_inherent_implementations_for_type(def_id.index)
-    }
-
     fn implementations_of_trait(&self, filter: Option<DefId>) -> Vec<DefId>
     {
         if let Some(def_id) = filter {

src/librustc_metadata/decoder.rs

@@ -643,10 +643,10 @@ impl<'a, 'tcx> CrateMetadata {
         self.get_impl_data(id).polarity
     }
 
-    pub fn get_custom_coerce_unsized_kind(&self,
-                                          id: DefIndex)
-                                          -> Option<ty::adjustment::CustomCoerceUnsized> {
-        self.get_impl_data(id).coerce_unsized_kind
+    pub fn get_coerce_unsized_info(&self,
+                                   id: DefIndex)
+                                   -> Option<ty::adjustment::CoerceUnsizedInfo> {
+        self.get_impl_data(id).coerce_unsized_info
     }
 
     pub fn get_impl_trait(&self,

src/librustc_metadata/encoder.rs

@@ -693,7 +693,7 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
                 let data = ImplData {
                     polarity: hir::ImplPolarity::Positive,
                     parent_impl: None,
-                    coerce_unsized_kind: None,
+                    coerce_unsized_info: None,
                     trait_ref: tcx.impl_trait_ref(def_id).map(|trait_ref| self.lazy(&trait_ref)),
                 };
 
@@ -713,13 +713,21 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
                     None
                 };
 
+                // if this is an impl of `CoerceUnsized`, create its
+                // "unsized info", else just store None
+                let coerce_unsized_info =
+                    trait_ref.and_then(|t| {
+                        if Some(t.def_id) == tcx.lang_items.coerce_unsized_trait() {
+                            Some(ty::queries::coerce_unsized_info::get(tcx, item.span, def_id))
+                        } else {
+                            None
+                        }
+                    });
+
                 let data = ImplData {
                     polarity: polarity,
                     parent_impl: parent,
-                    coerce_unsized_kind: tcx.maps.custom_coerce_unsized_kind
-                        .borrow()
-                        .get(&def_id)
-                        .cloned(),
+                    coerce_unsized_info: coerce_unsized_info,
                     trait_ref: trait_ref.map(|trait_ref| self.lazy(&trait_ref)),
                 };
 

src/librustc_metadata/schema.rs

@@ -285,7 +285,9 @@ pub struct TraitData<'tcx> {
 pub struct ImplData<'tcx> {
     pub polarity: hir::ImplPolarity,
     pub parent_impl: Option<DefId>,
-    pub coerce_unsized_kind: Option<ty::adjustment::CustomCoerceUnsized>,
+
+    /// This is `Some` only for impls of `CoerceUnsized`.
+    pub coerce_unsized_info: Option<ty::adjustment::CoerceUnsizedInfo>,
     pub trait_ref: Option<Lazy<ty::TraitRef<'tcx>>>,
 }