Auto merge of #30410 - Manishearth:rollup, r=Manishearth

- Successful merges: #30320, #30368, #30372, #30376, #30388, #30392
- Failed merges: #30354, #30389

src/libcollections/btree/set.rs

@@ -26,12 +26,17 @@ use Bound;
 
 /// A set based on a B-Tree.
 ///
-/// See BTreeMap's documentation for a detailed discussion of this collection's performance
+/// See [`BTreeMap`]'s documentation for a detailed discussion of this collection's performance
 /// benefits and drawbacks.
 ///
 /// It is a logic error for an item to be modified in such a way that the item's ordering relative
-/// to any other item, as determined by the `Ord` trait, changes while it is in the set. This is
-/// normally only possible through `Cell`, `RefCell`, global state, I/O, or unsafe code.
+/// to any other item, as determined by the [`Ord`] trait, changes while it is in the set. This is
+/// normally only possible through [`Cell`], [`RefCell`], global state, I/O, or unsafe code.
+///
+/// [`BTreeMap`]: ../struct.BTreeMap.html
+/// [`Ord`]: ../../core/cmp/trait.Ord.html
+/// [`Cell`]: ../../std/cell/struct.Cell.html
+/// [`RefCell`]: ../../std/cell/struct.RefCell.html
 #[derive(Clone, Hash, PartialEq, Eq, Ord, PartialOrd)]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct BTreeSet<T> {

src/librustc/middle/check_static_recursion.rs

@@ -99,8 +99,9 @@ pub fn check_crate<'ast>(sess: &Session,
         ast_map: ast_map,
         discriminant_map: RefCell::new(NodeMap()),
     };
-    krate.visit_all_items(&mut visitor);
-    sess.abort_if_errors();
+    sess.abort_if_new_errors(|| {
+        krate.visit_all_items(&mut visitor);
+    });
 }
 
 struct CheckItemRecursionVisitor<'a, 'ast: 'a> {

src/librustc/middle/def.rs

@@ -52,6 +52,7 @@ pub enum Def {
     DefStruct(DefId),
     DefLabel(ast::NodeId),
     DefMethod(DefId),
+    DefErr,
 }
 
 /// The result of resolving a path.
@@ -124,7 +125,7 @@ impl Def {
             DefVariant(..) | DefTy(..) | DefAssociatedTy(..) |
             DefTyParam(..) | DefUse(..) | DefStruct(..) | DefTrait(..) |
             DefMethod(..) | DefConst(..) | DefAssociatedConst(..) |
-            DefPrimTy(..) | DefLabel(..) | DefSelfTy(..) => {
+            DefPrimTy(..) | DefLabel(..) | DefSelfTy(..) | DefErr => {
                 panic!("attempted .def_id() on invalid {:?}", self)
             }
         }
@@ -142,7 +143,8 @@ impl Def {
 
             DefLabel(..)  |
             DefPrimTy(..) |
-            DefSelfTy(..) => {
+            DefSelfTy(..) |
+            DefErr => {
                 panic!("attempted .def_id() on invalid def: {:?}", self)
             }
         }

src/librustc/middle/infer/region_inference/mod.rs

@@ -18,6 +18,7 @@ pub use self::RegionResolutionError::*;
 pub use self::VarValue::*;
 
 use super::{RegionVariableOrigin, SubregionOrigin, TypeTrace, MiscVariable};
+use super::unify_key;
 
 use rustc_data_structures::graph::{self, Direction, NodeIndex};
 use rustc_data_structures::unify::{self, UnificationTable};
@@ -345,10 +346,13 @@ impl<'a, 'tcx> RegionVarBindings<'a, 'tcx> {
     }
 
     pub fn new_region_var(&self, origin: RegionVariableOrigin) -> RegionVid {
-        let id = self.num_vars();
+        let vid = RegionVid { index: self.num_vars() };
         self.var_origins.borrow_mut().push(origin.clone());
-        let vid = self.unification_table.borrow_mut().new_key(());
-        assert_eq!(vid.index, id);
+
+        let u_vid = self.unification_table.borrow_mut().new_key(
+            unify_key::RegionVidKey { min_vid: vid }
+            );
+        assert_eq!(vid, u_vid);
         if self.in_snapshot() {
             self.undo_log.borrow_mut().push(AddVar(vid));
         }
@@ -581,7 +585,7 @@ impl<'a, 'tcx> RegionVarBindings<'a, 'tcx> {
     }
 
     pub fn opportunistic_resolve_var(&self, rid: RegionVid) -> ty::Region {
-        ty::ReVar(self.unification_table.borrow_mut().find(rid))
+        ty::ReVar(self.unification_table.borrow_mut().find_value(rid).min_vid)
     }
 
     fn combine_map(&self, t: CombineMapType) -> &RefCell<CombineMap> {

src/librustc/middle/infer/unify_key.rs

@@ -10,7 +10,7 @@
 
 use syntax::ast;
 use middle::ty::{self, IntVarValue, Ty};
-use rustc_data_structures::unify::UnifyKey;
+use rustc_data_structures::unify::{Combine, UnifyKey};
 
 pub trait ToType<'tcx> {
     fn to_type(&self, tcx: &ty::ctxt<'tcx>) -> Ty<'tcx>;
@@ -23,8 +23,28 @@ impl UnifyKey for ty::IntVid {
     fn tag(_: Option<ty::IntVid>) -> &'static str { "IntVid" }
 }
 
+#[derive(PartialEq, Copy, Clone, Debug)]
+pub struct RegionVidKey {
+    /// The minimum region vid in the unification set. This is needed
+    /// to have a canonical name for a type to prevent infinite
+    /// recursion.
+    pub min_vid: ty::RegionVid
+}
+
+impl Combine for RegionVidKey {
+    fn combine(&self, other: &RegionVidKey) -> RegionVidKey {
+        let min_vid = if self.min_vid.index < other.min_vid.index {
+            self.min_vid
+        } else {
+            other.min_vid
+        };
+
+        RegionVidKey { min_vid: min_vid }
+    }
+}
+
 impl UnifyKey for ty::RegionVid {
-    type Value = ();
+    type Value = RegionVidKey;
     fn index(&self) -> u32 { self.index }
     fn from_index(i: u32) -> ty::RegionVid { ty::RegionVid { index: i } }
     fn tag(_: Option<ty::RegionVid>) -> &'static str { "RegionVid" }

src/librustc/middle/mem_categorization.rs

@@ -609,6 +609,8 @@ impl<'t, 'a,'tcx> MemCategorizationContext<'t, 'a, 'tcx> {
                 note: NoteNone
             }))
           }
+
+          def::DefErr => panic!("DefErr in memory categorization")
         }
     }
 
@@ -1196,7 +1198,7 @@ impl<'t, 'a,'tcx> MemCategorizationContext<'t, 'a, 'tcx> {
         (*op)(self, cmt.clone(), pat);
 
         let opt_def = if let Some(path_res) = self.tcx().def_map.borrow().get(&pat.id) {
-            if path_res.depth != 0 {
+            if path_res.depth != 0 || path_res.base_def == def::DefErr {
                 // Since patterns can be associated constants
                 // which are resolved during typeck, we might have
                 // some unresolved patterns reaching this stage
@@ -1261,7 +1263,7 @@ impl<'t, 'a,'tcx> MemCategorizationContext<'t, 'a, 'tcx> {
                 _ => {
                     self.tcx().sess.span_bug(
                         pat.span,
-                        "enum pattern didn't resolve to enum or struct");
+                        &format!("enum pattern didn't resolve to enum or struct {:?}", opt_def));
                 }
             }
           }

src/librustc/middle/resolve_lifetime.rs

@@ -95,15 +95,16 @@ static ROOT_SCOPE: ScopeChain<'static> = RootScope;
 
 pub fn krate(sess: &Session, krate: &hir::Crate, def_map: &DefMap) -> NamedRegionMap {
     let mut named_region_map = NodeMap();
-    krate.visit_all_items(&mut LifetimeContext {
-        sess: sess,
-        named_region_map: &mut named_region_map,
-        scope: &ROOT_SCOPE,
-        def_map: def_map,
-        trait_ref_hack: false,
-        labels_in_fn: vec![],
+    sess.abort_if_new_errors(|| {
+        krate.visit_all_items(&mut LifetimeContext {
+            sess: sess,
+            named_region_map: &mut named_region_map,
+            scope: &ROOT_SCOPE,
+            def_map: def_map,
+            trait_ref_hack: false,
+            labels_in_fn: vec![],
+        });
     });
-    sess.abort_if_errors();
     named_region_map
 }
 

src/librustc/middle/ty/mod.rs

@@ -2100,9 +2100,8 @@ impl<'tcx> ctxt<'tcx> {
                     }) => {
                         true
                     }
-
+                    Some(&def::PathResolution { base_def: def::DefErr, .. })=> true,
                     Some(..) => false,
-
                     None => self.sess.span_bug(expr.span, &format!(
                         "no def for path {}", expr.id))
                 }

src/librustc/session/mod.rs

@@ -156,6 +156,15 @@ impl Session {
             _ => {}
         }
     }
+    pub fn abort_if_new_errors<F>(&self, mut f: F)
+        where F: FnMut()
+    {
+        let count = self.err_count();
+        f();
+        if self.err_count() > count {
+            self.abort_if_errors();
+        }
+    }
     pub fn span_warn(&self, sp: Span, msg: &str) {
         if self.can_print_warnings {
             self.diagnostic().span_warn(sp, msg)

src/librustc_borrowck/borrowck/gather_loans/mod.rs

@@ -33,6 +33,8 @@ use rustc_front::hir::{Expr, FnDecl, Block, Pat};
 use rustc_front::intravisit;
 use rustc_front::intravisit::Visitor;
 
+use self::restrictions::RestrictionResult;
+
 mod lifetime;
 mod restrictions;
 mod gather_moves;
@@ -354,12 +356,12 @@ impl<'a, 'tcx> GatherLoanCtxt<'a, 'tcx> {
 
         // Create the loan record (if needed).
         let loan = match restr {
-            restrictions::Safe => {
+            RestrictionResult::Safe => {
                 // No restrictions---no loan record necessary
                 return;
             }
 
-            restrictions::SafeIf(loan_path, restricted_paths) => {
+            RestrictionResult::SafeIf(loan_path, restricted_paths) => {
                 let loan_scope = match loan_region {
                     ty::ReScope(scope) => scope,
 

src/librustc_borrowck/borrowck/gather_loans/restrictions.rs

@@ -10,8 +10,6 @@
 
 //! Computes the restrictions that result from a borrow.
 
-pub use self::RestrictionResult::*;
-
 use borrowck::*;
 use rustc::middle::expr_use_visitor as euv;
 use rustc::middle::mem_categorization as mc;
@@ -69,19 +67,19 @@ impl<'a, 'tcx> RestrictionsContext<'a, 'tcx> {
                 // are inherently non-aliasable, they can only be
                 // accessed later through the borrow itself and hence
                 // must inherently comply with its terms.
-                Safe
+                RestrictionResult::Safe
             }
 
             Categorization::Local(local_id) => {
                 // R-Variable, locally declared
                 let lp = new_lp(LpVar(local_id));
-                SafeIf(lp.clone(), vec![lp])
+                RestrictionResult::SafeIf(lp.clone(), vec![lp])
             }
 
             Categorization::Upvar(mc::Upvar { id, .. }) => {
                 // R-Variable, captured into closure
                 let lp = new_lp(LpUpvar(id));
-                SafeIf(lp.clone(), vec![lp])
+                RestrictionResult::SafeIf(lp.clone(), vec![lp])
             }
 
             Categorization::Downcast(cmt_base, _) => {
@@ -106,7 +104,7 @@ impl<'a, 'tcx> RestrictionsContext<'a, 'tcx> {
             }
 
             Categorization::StaticItem => {
-                Safe
+                RestrictionResult::Safe
             }
 
             Categorization::Deref(cmt_base, _, pk) => {
@@ -133,11 +131,11 @@ impl<'a, 'tcx> RestrictionsContext<'a, 'tcx> {
                                     cmt: cmt_base,
                                     code: err_borrowed_pointer_too_short(
                                         self.loan_region, lt)});
-                            return Safe;
+                            return RestrictionResult::Safe;
                         }
 
                         match bk {
-                            ty::ImmBorrow => Safe,
+                            ty::ImmBorrow => RestrictionResult::Safe,
                             ty::MutBorrow | ty::UniqueImmBorrow => {
                                 // R-Deref-Mut-Borrowed
                                 //
@@ -150,7 +148,7 @@ impl<'a, 'tcx> RestrictionsContext<'a, 'tcx> {
                         }
                     }
                     // Borrowck is not relevant for raw pointers
-                    mc::UnsafePtr(..) => Safe
+                    mc::UnsafePtr(..) => RestrictionResult::Safe
                 }
             }
         }
@@ -161,12 +159,12 @@ impl<'a, 'tcx> RestrictionsContext<'a, 'tcx> {
               cmt: &mc::cmt<'tcx>,
               elem: LoanPathElem) -> RestrictionResult<'tcx> {
         match result {
-            Safe => Safe,
-            SafeIf(base_lp, mut base_vec) => {
+            RestrictionResult::Safe => RestrictionResult::Safe,
+            RestrictionResult::SafeIf(base_lp, mut base_vec) => {
                 let v = LpExtend(base_lp, cmt.mutbl, elem);
                 let lp = Rc::new(LoanPath::new(v, cmt.ty));
                 base_vec.push(lp.clone());
-                SafeIf(lp, base_vec)
+                RestrictionResult::SafeIf(lp, base_vec)
             }
         }
     }

src/librustc_data_structures/unify/mod.rs

@@ -37,6 +37,16 @@ pub trait UnifyKey : Copy + Clone + Debug + PartialEq {
     fn tag(k: Option<Self>) -> &'static str;
 }
 
+/// This trait is implemented for unify values that can be
+/// combined. This relation should be a monoid.
+pub trait Combine {
+    fn combine(&self, other: &Self) -> Self;
+}
+
+impl Combine for () {
+    fn combine(&self, _other: &()) {}
+}
+
 /// Value of a unification key. We implement Tarjan's union-find
 /// algorithm: when two keys are unified, one of them is converted
 /// into a "redirect" pointing at the other. These redirects form a
@@ -243,23 +253,28 @@ impl<K:UnifyKey> sv::SnapshotVecDelegate for Delegate<K> {
 ///////////////////////////////////////////////////////////////////////////
 // Base union-find algorithm, where we are just making sets
 
-impl<'tcx,K> UnificationTable<K>
-    where K : UnifyKey<Value=()>,
+impl<'tcx,K:UnifyKey> UnificationTable<K>
+    where K::Value: Combine
 {
     pub fn union(&mut self, a_id: K, b_id: K) {
         let node_a = self.get(a_id);
         let node_b = self.get(b_id);
         let a_id = node_a.key();
         let b_id = node_b.key();
         if a_id != b_id {
-            self.unify(node_a, node_b, ());
+            let new_value = node_a.value.combine(&node_b.value);
+            self.unify(node_a, node_b, new_value);
         }
     }
 
     pub fn find(&mut self, id: K) -> K {
         self.get(id).key()
     }
 
+    pub fn find_value(&mut self, id: K) -> K::Value {
+        self.get(id).value
+    }
+
     pub fn unioned(&mut self, a_id: K, b_id: K) -> bool {
         self.find(a_id) == self.find(b_id)
     }

src/librustc_metadata/astencode.rs

@@ -407,7 +407,8 @@ impl tr for def::Def {
               def::DefUpvar(did1, nid1, index, nid2)
           }
           def::DefStruct(did) => def::DefStruct(did.tr(dcx)),
-          def::DefLabel(nid) => def::DefLabel(dcx.tr_id(nid))
+          def::DefLabel(nid) => def::DefLabel(dcx.tr_id(nid)),
+          def::DefErr => def::DefErr,
         }
     }
 }

src/librustc_resolve/build_reduced_graph.rs

@@ -709,7 +709,8 @@ impl<'a, 'b:'a, 'tcx:'b> GraphBuilder<'a, 'b, 'tcx> {
             DefUse(..) |
             DefUpvar(..) |
             DefLabel(..) |
-            DefSelfTy(..) => {
+            DefSelfTy(..) |
+            DefErr => {
                 panic!("didn't expect `{:?}`", def);
             }
         }