rustc: implement and use Default on more types.

src/Cargo.lock

@@ -659,6 +659,14 @@ dependencies = [
  "log 0.4.5 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "ena"
+version = "0.10.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "log 0.4.5 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "env_logger"
 version = "0.5.12"
@@ -2196,7 +2204,7 @@ name = "rustc_data_structures"
 version = "0.0.0"
 dependencies = [
  "cfg-if 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
- "ena 0.9.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "ena 0.10.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "graphviz 0.0.0",
  "log 0.4.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "parking_lot 0.6.4 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -3261,6 +3269,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum difference 2.0.0 (registry+https://github.com/rust-lang/crates.io-index)" = "524cbf6897b527295dff137cec09ecf3a05f4fddffd7dfcd1585403449e74198"
 "checksum either 1.5.0 (registry+https://github.com/rust-lang/crates.io-index)" = "3be565ca5c557d7f59e7cfcf1844f9e3033650c929c6566f511e8005f205c1d0"
 "checksum elasticlunr-rs 2.3.3 (registry+https://github.com/rust-lang/crates.io-index)" = "4837d77a1e157489a3933b743fd774ae75074e0e390b2b7f071530048a0d87ee"
+"checksum ena 0.10.1 (registry+https://github.com/rust-lang/crates.io-index)" = "25b4e5febb25f08c49f1b07dc33a182729a6b21edfb562b5aef95f78e0dbe5bb"
 "checksum ena 0.9.3 (registry+https://github.com/rust-lang/crates.io-index)" = "88dc8393b3c7352f94092497f6b52019643e493b6b890eb417cdb7c46117e621"
 "checksum env_logger 0.5.12 (registry+https://github.com/rust-lang/crates.io-index)" = "f4d7e69c283751083d53d01eac767407343b8b69c4bd70058e08adc2637cb257"
 "checksum env_logger 0.6.0 (registry+https://github.com/rust-lang/crates.io-index)" = "afb070faf94c85d17d50ca44f6ad076bce18ae92f0037d350947240a36e9d42e"

src/librustc/dep_graph/graph.rs

@@ -101,11 +101,11 @@ impl DepGraph {
         DepGraph {
             data: Some(Lrc::new(DepGraphData {
                 previous_work_products: prev_work_products,
-                dep_node_debug: Lock::new(Default::default()),
+                dep_node_debug: Default::default(),
                 current: Lock::new(CurrentDepGraph::new()),
                 previous: prev_graph,
                 colors: Lock::new(DepNodeColorMap::new(prev_graph_node_count)),
-                loaded_from_cache: Lock::new(Default::default()),
+                loaded_from_cache: Default::default(),
             })),
             fingerprints: Lrc::new(Lock::new(fingerprints)),
         }

src/librustc/hir/map/definitions.rs

@@ -36,6 +36,7 @@ use util::nodemap::NodeMap;
 /// Internally the DefPathTable holds a tree of DefKeys, where each DefKey
 /// stores the DefIndex of its parent.
 /// There is one DefPathTable for each crate.
+#[derive(Default)]
 pub struct DefPathTable {
     index_to_key: [Vec<DefKey>; 2],
     def_path_hashes: [Vec<DefPathHash>; 2],
@@ -153,7 +154,7 @@ impl Decodable for DefPathTable {
 /// The definition table containing node definitions.
 /// It holds the DefPathTable for local DefIds/DefPaths and it also stores a
 /// mapping from NodeIds to local DefIds.
-#[derive(Clone)]
+#[derive(Clone, Default)]
 pub struct Definitions {
     table: DefPathTable,
     node_to_def_index: NodeMap<DefIndex>,
@@ -412,20 +413,8 @@ impl Definitions {
     ///     ascending order.
     ///
     /// FIXME: there is probably a better place to put this comment.
-    pub fn new() -> Definitions {
-        Definitions {
-            table: DefPathTable {
-                index_to_key: [vec![], vec![]],
-                def_path_hashes: [vec![], vec![]],
-            },
-            node_to_def_index: Default::default(),
-            def_index_to_node: [vec![], vec![]],
-            node_to_hir_id: IndexVec::new(),
-            parent_modules_of_macro_defs: Default::default(),
-            expansions_that_defined: Default::default(),
-            next_disambiguator: Default::default(),
-            def_index_to_span: Default::default(),
-        }
+    pub fn new() -> Self {
+        Self::default()
     }
 
     pub fn def_path_table(&self) -> &DefPathTable {

src/librustc/ich/hcx.rs

@@ -369,8 +369,7 @@ impl<'a> HashStable<StableHashingContext<'a>> for Span {
             // times, we cache a stable hash of it and hash that instead of
             // recursing every time.
             thread_local! {
-                static CACHE: RefCell<FxHashMap<hygiene::Mark, u64>> =
-                    RefCell::new(Default::default());
+                static CACHE: RefCell<FxHashMap<hygiene::Mark, u64>> = Default::default();
             }
 
             let sub_hash: u64 = CACHE.with(|cache| {

src/librustc/infer/region_constraints/mod.rs

@@ -29,6 +29,7 @@ use std::{cmp, fmt, mem, u32};
 
 mod taint;
 
+#[derive(Default)]
 pub struct RegionConstraintCollector<'tcx> {
     /// For each `RegionVid`, the corresponding `RegionVariableOrigin`.
     var_infos: IndexVec<RegionVid, RegionVariableInfo>,
@@ -341,17 +342,8 @@ impl TaintDirections {
 }
 
 impl<'tcx> RegionConstraintCollector<'tcx> {
-    pub fn new() -> RegionConstraintCollector<'tcx> {
-        RegionConstraintCollector {
-            var_infos: VarInfos::default(),
-            data: RegionConstraintData::default(),
-            lubs: Default::default(),
-            glbs: Default::default(),
-            bound_count: 0,
-            undo_log: Vec::new(),
-            unification_table: ut::UnificationTable::new(),
-            any_unifications: false,
-        }
+    pub fn new() -> Self {
+        Self::default()
     }
 
     pub fn num_region_vars(&self) -> usize {

src/librustc/lint/context.rs

@@ -1233,7 +1233,7 @@ pub fn check_ast_crate(
     let (passes, buffered) = if pre_expansion {
         (
             sess.lint_store.borrow_mut().pre_expansion_passes.take(),
-            LintBuffer::new(),
+            LintBuffer::default(),
         )
     } else {
         (

src/librustc/lint/mod.rs

@@ -490,15 +490,12 @@ mod levels;
 
 pub use self::levels::{LintLevelSets, LintLevelMap};
 
+#[derive(Default)]
 pub struct LintBuffer {
     map: NodeMap<Vec<BufferedEarlyLint>>,
 }
 
 impl LintBuffer {
-    pub fn new() -> LintBuffer {
-        LintBuffer { map: ::std::default::Default::default() }
-    }
-
     pub fn add_lint(&mut self,
                     lint: &'static Lint,
                     id: ast::NodeId,

src/librustc/middle/borrowck.rs

@@ -18,9 +18,15 @@ use rustc_data_structures::stable_hasher::{HashStable, StableHasher,
 #[derive(Copy, Clone, Debug, RustcEncodable, RustcDecodable)]
 pub enum SignalledError { SawSomeError, NoErrorsSeen }
 
+impl Default for SignalledError {
+    fn default() -> SignalledError {
+        SignalledError::NoErrorsSeen
+    }
+}
+
 impl_stable_hash_for!(enum self::SignalledError { SawSomeError, NoErrorsSeen });
 
-#[derive(Debug, RustcEncodable, RustcDecodable)]
+#[derive(Debug, Default, RustcEncodable, RustcDecodable)]
 pub struct BorrowCheckResult {
     pub used_mut_nodes: FxHashSet<HirId>,
     pub signalled_any_error: SignalledError,

src/librustc/middle/resolve_lifetime.rs

@@ -2741,9 +2741,7 @@ fn insert_late_bound_lifetimes(
         constrained_by_input.visit_ty(arg_ty);
     }
 
-    let mut appears_in_output = AllCollector {
-        regions: Default::default(),
-    };
+    let mut appears_in_output = AllCollector::default();
     intravisit::walk_fn_ret_ty(&mut appears_in_output, &decl.output);
 
     debug!(
@@ -2755,9 +2753,7 @@ fn insert_late_bound_lifetimes(
     //
     // Subtle point: because we disallow nested bindings, we can just
     // ignore binders here and scrape up all names we see.
-    let mut appears_in_where_clause = AllCollector {
-        regions: Default::default(),
-    };
+    let mut appears_in_where_clause = AllCollector::default();
     appears_in_where_clause.visit_generics(generics);
 
     for param in &generics.params {
@@ -2854,6 +2850,7 @@ fn insert_late_bound_lifetimes(
         }
     }
 
+    #[derive(Default)]
     struct AllCollector {
         regions: FxHashSet<hir::LifetimeName>,
     }

src/librustc/session/mod.rs

@@ -1149,7 +1149,7 @@ pub fn build_session_(
         local_crate_source_file,
         working_dir,
         lint_store: RwLock::new(lint::LintStore::new()),
-        buffered_lints: Lock::new(Some(lint::LintBuffer::new())),
+        buffered_lints: Lock::new(Some(Default::default())),
         one_time_diagnostics: Default::default(),
         plugin_llvm_passes: OneThread::new(RefCell::new(Vec::new())),
         plugin_attributes: OneThread::new(RefCell::new(Vec::new())),

src/librustc/ty/mod.rs

@@ -3183,7 +3183,7 @@ pub fn provide(providers: &mut ty::query::Providers<'_>) {
 /// rather, you should request the vector for a specific type via
 /// `tcx.inherent_impls(def_id)` so as to minimize your dependencies
 /// (constructing this map requires touching the entire crate).
-#[derive(Clone, Debug)]
+#[derive(Clone, Debug, Default)]
 pub struct CrateInherentImpls {
     pub inherent_impls: DefIdMap<Lrc<Vec<DefId>>>,
 }

src/librustc_codegen_ssa/back/symbol_export.rs

@@ -64,7 +64,7 @@ fn reachable_non_generics_provider<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
     assert_eq!(cnum, LOCAL_CRATE);
 
     if !tcx.sess.opts.output_types.should_codegen() {
-        return Lrc::new(Default::default())
+        return Default::default();
     }
 
     // Check to see if this crate is a "special runtime crate". These

src/librustc_data_structures/Cargo.toml

@@ -9,7 +9,7 @@ path = "lib.rs"
 crate-type = ["dylib"]
 
 [dependencies]
-ena = "0.9.3"
+ena = "0.10.1"
 log = "0.4"
 rustc_cratesio_shim = { path = "../librustc_cratesio_shim" }
 serialize = { path = "../libserialize" }

src/librustc_data_structures/snapshot_map/mod.rs

@@ -23,6 +23,18 @@ pub struct SnapshotMap<K, V>
     undo_log: Vec<UndoLog<K, V>>,
 }
 
+// HACK(eddyb) manual impl avoids `Default` bounds on `K` and `V`.
+impl<K, V> Default for SnapshotMap<K, V>
+    where K: Hash + Clone + Eq
+{
+    fn default() -> Self {
+        SnapshotMap {
+            map: Default::default(),
+            undo_log: Default::default(),
+        }
+    }
+}
+
 pub struct Snapshot {
     len: usize,
 }
@@ -35,17 +47,6 @@ enum UndoLog<K, V> {
     Noop,
 }
 
-impl<K, V> Default for SnapshotMap<K, V>
-    where K: Hash + Clone + Eq
-{
-    fn default() -> Self {
-        SnapshotMap {
-            map: FxHashMap::default(),
-            undo_log: vec![],
-        }
-    }
-}
-
 impl<K, V> SnapshotMap<K, V>
     where K: Hash + Clone + Eq
 {

src/librustc_data_structures/transitive_relation.rs

@@ -42,6 +42,18 @@ pub struct TransitiveRelation<T: Clone + Debug + Eq + Hash> {
     closure: Lock<Option<BitMatrix<usize, usize>>>,
 }
 
+// HACK(eddyb) manual impl avoids `Default` bound on `T`.
+impl<T: Clone + Debug + Eq + Hash> Default for TransitiveRelation<T> {
+    fn default() -> Self {
+        TransitiveRelation {
+            elements: Default::default(),
+            map: Default::default(),
+            edges: Default::default(),
+            closure: Default::default(),
+        }
+    }
+}
+
 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable, Debug)]
 struct Index(usize);
 
@@ -51,17 +63,6 @@ struct Edge {
     target: Index,
 }
 
-impl<T: Clone + Debug + Eq + Hash> Default for TransitiveRelation<T> {
-    fn default() -> TransitiveRelation<T> {
-        TransitiveRelation {
-            elements: vec![],
-            map: FxHashMap::default(),
-            edges: vec![],
-            closure: Lock::new(None),
-        }
-    }
-}
-
 impl<T: Clone + Debug + Eq + Hash> TransitiveRelation<T> {
     pub fn is_empty(&self) -> bool {
         self.edges.is_empty()

src/librustc_typeck/coherence/inherent_impls.rs

@@ -22,7 +22,6 @@ use rustc::hir::def_id::{CrateNum, DefId, LOCAL_CRATE};
 use rustc::hir;
 use rustc::hir::itemlikevisit::ItemLikeVisitor;
 use rustc::ty::{self, CrateInherentImpls, TyCtxt};
-use rustc::util::nodemap::DefIdMap;
 
 use rustc_data_structures::sync::Lrc;
 use syntax::ast;
@@ -37,9 +36,7 @@ pub fn crate_inherent_impls<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
     let krate = tcx.hir.krate();
     let mut collect = InherentCollect {
         tcx,
-        impls_map: CrateInherentImpls {
-            inherent_impls: DefIdMap::default()
-        }
+        impls_map: Default::default(),
     };
     krate.visit_all_item_likes(&mut collect);
     Lrc::new(collect.impls_map)