8 files changed, 26 insertions, 94 deletions

diff --git a/Cargo.lock b/Cargo.lock
index 4666347f8..b06058688 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -371,11 +371,6 @@ version = "1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
-name = "id-arena"
-version = "2.0.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-
-[[package]]
 name = "idna"
 version = "0.1.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -733,9 +728,9 @@ dependencies = [
  "arrayvec 0.4.10 (registry+https://github.com/rust-lang/crates.io-index)",
  "ena 0.11.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "flexi_logger 0.10.3 (registry+https://github.com/rust-lang/crates.io-index)",
- "id-arena 2.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "parking_lot 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "ra_arena 0.1.0",
  "ra_db 0.1.0",
  "ra_editor 0.1.0",
  "ra_syntax 0.1.0",
@@ -1534,7 +1529,6 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum glob 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)" = "8be18de09a56b60ed0edf84bc9df007e30040691af7acd1c41874faac5895bfb"
 "checksum heck 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)" = "20564e78d53d2bb135c343b3f47714a56af2061f1c928fdb541dc7b9fdd94205"
 "checksum humansize 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "b6cab2627acfc432780848602f3f558f7e9dd427352224b0d9324025796d2a5e"
-"checksum id-arena 2.0.0 (registry+https://github.com/rust-lang/crates.io-index)" = "3a7250033feafee46a1cecd2c2616a64aec1d064f38c9ae2bdd297728542843e"
 "checksum idna 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)" = "38f09e0f0b1fb55fdee1f17470ad800da77af5186a1a76c026b679358b7e844e"
 "checksum im 12.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "ae9c7f9bb8aee47fc16d535a705f7867a9fc83bb822e5e1043bb98e77ffeed3c"
 "checksum indexmap 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)" = "7e81a7c05f79578dbc15793d8b619db9ba32b4577003ef3af1a91c416798c58d"
diff --git a/crates/ra_arena/src/lib.rs b/crates/ra_arena/src/lib.rs
index 44d9e826b..a5eeb4118 100644
--- a/crates/ra_arena/src/lib.rs
+++ b/crates/ra_arena/src/lib.rs
@@ -33,7 +33,7 @@ impl fmt::Display for RawId {
     }
 }
 
-#[derive(Clone, Debug)]
+#[derive(Clone, Debug, PartialEq, Eq)]
 pub struct Arena<ID: ArenaId, T> {
     data: Vec<T>,
     _ty: PhantomData<ID>,
diff --git a/crates/ra_hir/Cargo.toml b/crates/ra_hir/Cargo.toml
index c3fbd327d..8c0cf4b86 100644
--- a/crates/ra_hir/Cargo.toml
+++ b/crates/ra_hir/Cargo.toml
@@ -11,9 +11,9 @@ relative-path = "0.4.0"
 salsa = "0.9.0"
 rustc-hash = "1.0"
 parking_lot = "0.7.0"
-id-arena = "2.0"
 ena = "0.11"
 ra_syntax = { path = "../ra_syntax" }
+ra_arena = { path = "../ra_arena" }
 ra_editor = { path = "../ra_editor" }
 ra_db = { path = "../ra_db" }
 test_utils = { path = "../test_utils" }
diff --git a/crates/ra_hir/src/arena.rs b/crates/ra_hir/src/arena.rs
deleted file mode 100644
index d4f9d9cb9..000000000
--- a/crates/ra_hir/src/arena.rs
+++ /dev/null
@@ -1,66 +0,0 @@
-//! A simple id-based arena, similar to https://github.com/fitzgen/id-arena.
-//! We use our own version for more compact id's and to allow inherent impls
-//! on Ids.
-
-use std::{
-    fmt,
-    hash::{Hash, Hasher},
-    marker::PhantomData,
-};
-
-pub struct Id<T> {
-    idx: u32,
-    _ty: PhantomData<fn() -> T>,
-}
-
-impl<T> fmt::Debug for Id<T> {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        f.debug_tuple("Id").field(&self.idx).finish()
-    }
-}
-impl<T> Copy for Id<T> {}
-impl<T> Clone for Id<T> {
-    fn clone(&self) -> Id<T> {
-        *self
-    }
-}
-
-impl<T> PartialEq for Id<T> {
-    fn eq(&self, other: &Id<T>) -> bool {
-        self.idx == other.idx
-    }
-}
-
-impl<T> Eq for Id<T> {}
-
-impl<T> Hash for Id<T> {
-    fn hash<H: Hasher>(&self, h: &mut H) {
-        self.idx.hash(h);
-    }
-}
-
-#[derive(Debug, PartialEq, Eq)]
-pub(crate) struct ArenaBehavior<T> {
-    _ty: PhantomData<T>,
-}
-
-impl<T> id_arena::ArenaBehavior for ArenaBehavior<T> {
-    type Id = Id<T>;
-    fn new_arena_id() -> u32 {
-        0
-    }
-    fn new_id(_arena_id: u32, index: usize) -> Id<T> {
-        Id {
-            idx: index as u32,
-            _ty: PhantomData,
-        }
-    }
-    fn index(id: Id<T>) -> usize {
-        id.idx as usize
-    }
-    fn arena_id(_id: Id<T>) -> u32 {
-        0
-    }
-}
-
-pub(crate) type Arena<T> = id_arena::Arena<T, ArenaBehavior<T>>;
diff --git a/crates/ra_hir/src/function/scope.rs b/crates/ra_hir/src/function/scope.rs
index 3e4cfad0c..42bfe4f32 100644
--- a/crates/ra_hir/src/function/scope.rs
+++ b/crates/ra_hir/src/function/scope.rs
@@ -5,19 +5,19 @@ use ra_syntax::{
     algo::generate,
     ast::{self, ArgListOwner, LoopBodyOwner, NameOwner},
 };
+use ra_arena::{Arena, RawId, impl_arena_id};
 use ra_db::LocalSyntaxPtr;
 
-use crate::{
-    arena::{Arena, Id},
-    Name, AsName,
-};
+use crate::{Name, AsName};
 
-pub(crate) type ScopeId = Id<ScopeData>;
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct ScopeId(RawId);
+impl_arena_id!(ScopeId);
 
 #[derive(Debug, PartialEq, Eq)]
 pub struct FnScopes {
     pub self_param: Option<LocalSyntaxPtr>,
-    scopes: Arena<ScopeData>,
+    scopes: Arena<ScopeId, ScopeData>,
     scope_for: FxHashMap<LocalSyntaxPtr, ScopeId>,
 }
 
diff --git a/crates/ra_hir/src/ids.rs b/crates/ra_hir/src/ids.rs
index 4c7ebe3ea..66adacc7d 100644
--- a/crates/ra_hir/src/ids.rs
+++ b/crates/ra_hir/src/ids.rs
@@ -1,10 +1,8 @@
 use ra_db::{SourceRootId, LocationIntener, Cancelable, FileId};
 use ra_syntax::{SourceFileNode, SyntaxKind, SyntaxNode, SyntaxNodeRef, SourceFile, AstNode, ast};
+use ra_arena::{Arena, RawId, impl_arena_id};
 
-use crate::{
-    HirDatabase, PerNs, ModuleId, Module, Def, Function, Struct, Enum,
-    arena::{Arena, Id},
-};
+use crate::{HirDatabase, PerNs, ModuleId, Module, Def, Function, Struct, Enum};
 
 /// hir makes a heavy use of ids: integer (u32) handlers to various things. You
 /// can think of id as a pointer (but without a lifetime) or a file descriptor
@@ -206,7 +204,9 @@ impl DefKind {
 
 /// Identifier of item within a specific file. This is stable over reparses, so
 /// it's OK to use it as a salsa key/value.
-pub(crate) type SourceFileItemId = Id<SyntaxNode>;
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct SourceFileItemId(RawId);
+impl_arena_id!(SourceFileItemId);
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct SourceItemId {
@@ -219,7 +219,7 @@ pub struct SourceItemId {
 #[derive(Debug, PartialEq, Eq)]
 pub struct SourceFileItems {
     file_id: HirFileId,
-    arena: Arena<SyntaxNode>,
+    arena: Arena<SourceFileItemId, SyntaxNode>,
 }
 
 impl SourceFileItems {
diff --git a/crates/ra_hir/src/lib.rs b/crates/ra_hir/src/lib.rs
index 8ee52a466..344b543b6 100644
--- a/crates/ra_hir/src/lib.rs
+++ b/crates/ra_hir/src/lib.rs
@@ -19,7 +19,6 @@ pub mod db;
 mod mock;
 mod query_definitions;
 mod path;
-mod arena;
 pub mod source_binder;
 
 mod ids;
diff --git a/crates/ra_hir/src/module.rs b/crates/ra_hir/src/module.rs
index a53b69d20..c70dc54dd 100644
--- a/crates/ra_hir/src/module.rs
+++ b/crates/ra_hir/src/module.rs
@@ -9,6 +9,7 @@ use ra_syntax::{
     ast::{self, AstNode, NameOwner},
     SyntaxNode,
 };
+use ra_arena::{Arena, RawId, impl_arena_id};
 use ra_db::{SourceRootId, FileId, Cancelable};
 use relative_path::RelativePathBuf;
 
@@ -16,7 +17,6 @@ use crate::{
     Def, DefKind, DefLoc, DefId,
     Name, Path, PathKind, HirDatabase, SourceItemId, SourceFileItemId, Crate,
     HirFileId,
-    arena::{Arena, Id},
 };
 
 pub use self::nameres::{ModuleScope, Resolution, Namespace, PerNs};
@@ -173,6 +173,14 @@ impl Module {
     }
 }
 
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct ModuleId(RawId);
+impl_arena_id!(ModuleId);
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct LinkId(RawId);
+impl_arena_id!(LinkId);
+
 /// Physically, rust source is organized as a set of files, but logically it is
 /// organized as a tree of modules. Usually, a single file corresponds to a
 /// single module, but it is not nessary the case.
@@ -182,8 +190,8 @@ impl Module {
 /// always have one parent).
 #[derive(Default, Debug, PartialEq, Eq)]
 pub struct ModuleTree {
-    mods: Arena<ModuleData>,
-    links: Arena<LinkData>,
+    mods: Arena<ModuleId, ModuleData>,
+    links: Arena<LinkId, LinkData>,
 }
 
 impl ModuleTree {
@@ -210,9 +218,6 @@ pub(crate) enum ModuleSourceNode {
     Module(ast::ModuleNode),
 }
 
-pub type ModuleId = Id<ModuleData>;
-type LinkId = Id<LinkData>;
-
 #[derive(Clone, Debug, Hash, PartialEq, Eq)]
 pub enum Problem {
     UnresolvedModule {