Auto merge of #52591 - eddyb:functional-snakes, r=oli-obk

rustc: remove {FxHash,Node,DefId,HirId,ItemLocal}{Map,Set} "constructor" fns.

These are cruft left over from a time when `Foo::default()` didn't "just work".

Author: bors

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/lowering.rs

@@ -244,9 +244,9 @@ pub fn lower_crate(
         loop_scopes: Vec::new(),
         is_in_loop_condition: false,
         anonymous_lifetime_mode: AnonymousLifetimeMode::PassThrough,
-        type_def_lifetime_params: DefIdMap(),
+        type_def_lifetime_params: Default::default(),
         current_hir_id_owner: vec![(CRATE_DEF_INDEX, 0)],
-        item_local_id_counters: NodeMap(),
+        item_local_id_counters: Default::default(),
         node_id_to_hir_id: IndexVec::new(),
         is_generator: false,
         is_in_trait_impl: false,
@@ -1168,7 +1168,7 @@ impl<'a> LoweringContext<'a> {
                             hir::TyKind::BareFn(P(hir::BareFnTy {
                                 generic_params: this.lower_generic_params(
                                     &f.generic_params,
-                                    &NodeMap(),
+                                    &NodeMap::default(),
                                     ImplTraitContext::disallowed(),
                                 ),
                                 unsafety: this.lower_unsafety(f.unsafety),
@@ -2467,7 +2467,7 @@ impl<'a> LoweringContext<'a> {
         // FIXME: This could probably be done with less rightward drift. Also looks like two control
         //        paths where report_error is called are also the only paths that advance to after
         //        the match statement, so the error reporting could probably just be moved there.
-        let mut add_bounds: NodeMap<Vec<_>> = NodeMap();
+        let mut add_bounds: NodeMap<Vec<_>> = Default::default();
         for pred in &generics.where_clause.predicates {
             if let WherePredicate::BoundPredicate(ref bound_pred) = *pred {
                 'next_bound: for bound in &bound_pred.bounds {
@@ -2552,7 +2552,7 @@ impl<'a> LoweringContext<'a> {
                         hir::WherePredicate::BoundPredicate(hir::WhereBoundPredicate {
                             bound_generic_params: this.lower_generic_params(
                                 bound_generic_params,
-                                &NodeMap(),
+                                &NodeMap::default(),
                                 ImplTraitContext::disallowed(),
                             ),
                             bounded_ty: this.lower_ty(bounded_ty, ImplTraitContext::disallowed()),
@@ -2636,8 +2636,11 @@ impl<'a> LoweringContext<'a> {
         p: &PolyTraitRef,
         mut itctx: ImplTraitContext<'_>,
     ) -> hir::PolyTraitRef {
-        let bound_generic_params =
-            self.lower_generic_params(&p.bound_generic_params, &NodeMap(), itctx.reborrow());
+        let bound_generic_params = self.lower_generic_params(
+            &p.bound_generic_params,
+            &NodeMap::default(),
+            itctx.reborrow(),
+        );
         let trait_ref = self.with_parent_impl_lifetime_defs(
             &bound_generic_params,
             |this| this.lower_trait_ref(&p.trait_ref, itctx),

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: NodeMap(),
-            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/opaque_types/mod.rs

@@ -121,7 +121,7 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
             parent_def_id,
             body_id,
             param_env,
-            opaque_types: DefIdMap(),
+            opaque_types: Default::default(),
             obligations: vec![],
         };
         let value = instantiator.instantiate_opaque_types_in_map(value);

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: NodeMap() }
-    }
-
     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,