30 files changed, 28 insertions, 253 deletions

diff --git a/crates/arena/Cargo.toml b/crates/arena/Cargo.toml
deleted file mode 100644
index 863eedf76..000000000
--- a/crates/arena/Cargo.toml
+++ /dev/null
@@ -1,10 +0,0 @@
-[package]
-name = "arena"
-version = "0.0.0"
-description = "TBD"
-license = "MIT OR Apache-2.0"
-authors = ["rust-analyzer developers"]
-edition = "2018"
-
-[lib]
-doctest = false
diff --git a/crates/arena/src/lib.rs b/crates/arena/src/lib.rs
deleted file mode 100644
index 3169aa5b8..000000000
--- a/crates/arena/src/lib.rs
+++ /dev/null
@@ -1,152 +0,0 @@
-//! Yet another index-based arena.
-
-use std::{
-    fmt,
-    hash::{Hash, Hasher},
-    iter::FromIterator,
-    marker::PhantomData,
-    ops::{Index, IndexMut},
-};
-
-pub mod map;
-
-#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
-pub struct RawId(u32);
-
-impl From<RawId> for u32 {
-    fn from(raw: RawId) -> u32 {
-        raw.0
-    }
-}
-
-impl From<u32> for RawId {
-    fn from(id: u32) -> RawId {
-        RawId(id)
-    }
-}
-
-impl fmt::Debug for RawId {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        self.0.fmt(f)
-    }
-}
-
-impl fmt::Display for RawId {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        self.0.fmt(f)
-    }
-}
-
-pub struct Idx<T> {
-    raw: RawId,
-    _ty: PhantomData<fn() -> T>,
-}
-
-impl<T> Clone for Idx<T> {
-    fn clone(&self) -> Self {
-        *self
-    }
-}
-impl<T> Copy for Idx<T> {}
-
-impl<T> PartialEq for Idx<T> {
-    fn eq(&self, other: &Idx<T>) -> bool {
-        self.raw == other.raw
-    }
-}
-impl<T> Eq for Idx<T> {}
-
-impl<T> Hash for Idx<T> {
-    fn hash<H: Hasher>(&self, state: &mut H) {
-        self.raw.hash(state)
-    }
-}
-
-impl<T> fmt::Debug for Idx<T> {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        let mut type_name = std::any::type_name::<T>();
-        if let Some(idx) = type_name.rfind(':') {
-            type_name = &type_name[idx + 1..]
-        }
-        write!(f, "Idx::<{}>({})", type_name, self.raw)
-    }
-}
-
-impl<T> Idx<T> {
-    pub fn from_raw(raw: RawId) -> Self {
-        Idx { raw, _ty: PhantomData }
-    }
-    pub fn into_raw(self) -> RawId {
-        self.raw
-    }
-}
-
-#[derive(Clone, PartialEq, Eq)]
-pub struct Arena<T> {
-    data: Vec<T>,
-}
-
-impl<T: fmt::Debug> fmt::Debug for Arena<T> {
-    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
-        fmt.debug_struct("Arena").field("len", &self.len()).field("data", &self.data).finish()
-    }
-}
-
-impl<T> Arena<T> {
-    pub const fn new() -> Arena<T> {
-        Arena { data: Vec::new() }
-    }
-    pub fn clear(&mut self) {
-        self.data.clear();
-    }
-
-    pub fn len(&self) -> usize {
-        self.data.len()
-    }
-    pub fn is_empty(&self) -> bool {
-        self.data.is_empty()
-    }
-    pub fn alloc(&mut self, value: T) -> Idx<T> {
-        let id = RawId(self.data.len() as u32);
-        self.data.push(value);
-        Idx::from_raw(id)
-    }
-    pub fn iter(
-        &self,
-    ) -> impl Iterator<Item = (Idx<T>, &T)> + ExactSizeIterator + DoubleEndedIterator {
-        self.data.iter().enumerate().map(|(idx, value)| (Idx::from_raw(RawId(idx as u32)), value))
-    }
-    pub fn shrink_to_fit(&mut self) {
-        self.data.shrink_to_fit();
-    }
-}
-
-impl<T> Default for Arena<T> {
-    fn default() -> Arena<T> {
-        Arena { data: Vec::new() }
-    }
-}
-
-impl<T> Index<Idx<T>> for Arena<T> {
-    type Output = T;
-    fn index(&self, idx: Idx<T>) -> &T {
-        let idx = idx.into_raw().0 as usize;
-        &self.data[idx]
-    }
-}
-
-impl<T> IndexMut<Idx<T>> for Arena<T> {
-    fn index_mut(&mut self, idx: Idx<T>) -> &mut T {
-        let idx = idx.into_raw().0 as usize;
-        &mut self.data[idx]
-    }
-}
-
-impl<T> FromIterator<T> for Arena<T> {
-    fn from_iter<I>(iter: I) -> Self
-    where
-        I: IntoIterator<Item = T>,
-    {
-        Arena { data: Vec::from_iter(iter) }
-    }
-}
diff --git a/crates/arena/src/map.rs b/crates/arena/src/map.rs
deleted file mode 100644
index 0f33907c0..000000000
--- a/crates/arena/src/map.rs
+++ /dev/null
@@ -1,62 +0,0 @@
-//! A map from arena IDs to some other type. Space requirement is O(highest ID).
-
-use std::marker::PhantomData;
-
-use crate::Idx;
-
-/// A map from arena IDs to some other type. Space requirement is O(highest ID).
-#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
-pub struct ArenaMap<ID, V> {
-    v: Vec<Option<V>>,
-    _ty: PhantomData<ID>,
-}
-
-impl<T, V> ArenaMap<Idx<T>, V> {
-    pub fn insert(&mut self, id: Idx<T>, t: V) {
-        let idx = Self::to_idx(id);
-
-        self.v.resize_with((idx + 1).max(self.v.len()), || None);
-        self.v[idx] = Some(t);
-    }
-
-    pub fn get(&self, id: Idx<T>) -> Option<&V> {
-        self.v.get(Self::to_idx(id)).and_then(|it| it.as_ref())
-    }
-
-    pub fn get_mut(&mut self, id: Idx<T>) -> Option<&mut V> {
-        self.v.get_mut(Self::to_idx(id)).and_then(|it| it.as_mut())
-    }
-
-    pub fn values(&self) -> impl Iterator<Item = &V> {
-        self.v.iter().filter_map(|o| o.as_ref())
-    }
-
-    pub fn values_mut(&mut self) -> impl Iterator<Item = &mut V> {
-        self.v.iter_mut().filter_map(|o| o.as_mut())
-    }
-
-    pub fn iter(&self) -> impl Iterator<Item = (Idx<T>, &V)> {
-        self.v.iter().enumerate().filter_map(|(idx, o)| Some((Self::from_idx(idx), o.as_ref()?)))
-    }
-
-    fn to_idx(id: Idx<T>) -> usize {
-        u32::from(id.into_raw()) as usize
-    }
-
-    fn from_idx(idx: usize) -> Idx<T> {
-        Idx::from_raw((idx as u32).into())
-    }
-}
-
-impl<T, V> std::ops::Index<Idx<V>> for ArenaMap<Idx<V>, T> {
-    type Output = T;
-    fn index(&self, id: Idx<V>) -> &T {
-        self.v[Self::to_idx(id)].as_ref().unwrap()
-    }
-}
-
-impl<T, V> Default for ArenaMap<Idx<V>, T> {
-    fn default() -> Self {
-        ArenaMap { v: Vec::new(), _ty: PhantomData }
-    }
-}
diff --git a/crates/hir_def/Cargo.toml b/crates/hir_def/Cargo.toml
index 7ef966cd2..5d21283f7 100644
--- a/crates/hir_def/Cargo.toml
+++ b/crates/hir_def/Cargo.toml
@@ -20,9 +20,9 @@ fst = { version = "0.4", default-features = false }
 itertools = "0.10.0"
 indexmap = "1.4.0"
 smallvec = "1.4.0"
+la-arena = "0.1.0"
 
 stdx = { path = "../stdx", version = "0.0.0" }
-arena = { path = "../arena", version = "0.0.0" }
 base_db = { path = "../base_db", version = "0.0.0" }
 syntax = { path = "../syntax", version = "0.0.0" }
 profile = { path = "../profile", version = "0.0.0" }
diff --git a/crates/hir_def/src/adt.rs b/crates/hir_def/src/adt.rs
index 236d6f1b7..237c3d3f9 100644
--- a/crates/hir_def/src/adt.rs
+++ b/crates/hir_def/src/adt.rs
@@ -2,13 +2,13 @@
 
 use std::sync::Arc;
 
-use arena::{map::ArenaMap, Arena};
 use base_db::CrateId;
 use either::Either;
 use hir_expand::{
     name::{AsName, Name},
     InFile,
 };
+use la_arena::{map::ArenaMap, Arena};
 use syntax::ast::{self, NameOwner, VisibilityOwner};
 use tt::{Delimiter, DelimiterKind, Leaf, Subtree, TokenTree};
 
diff --git a/crates/hir_def/src/attr.rs b/crates/hir_def/src/attr.rs
index 9e6426b31..5a86823c2 100644
--- a/crates/hir_def/src/attr.rs
+++ b/crates/hir_def/src/attr.rs
@@ -2,12 +2,12 @@
 
 use std::{ops, sync::Arc};
 
-use arena::map::ArenaMap;
 use base_db::CrateId;
 use cfg::{CfgExpr, CfgOptions};
 use either::Either;
 use hir_expand::{hygiene::Hygiene, name::AsName, AstId, InFile};
 use itertools::Itertools;
+use la_arena::map::ArenaMap;
 use mbe::ast_to_token_tree;
 use syntax::{
     ast::{self, AstNode, AttrsOwner},
diff --git a/crates/hir_def/src/body.rs b/crates/hir_def/src/body.rs
index d07004b9d..43ee57277 100644
--- a/crates/hir_def/src/body.rs
+++ b/crates/hir_def/src/body.rs
@@ -8,7 +8,6 @@ pub mod scope;
 
 use std::{mem, ops::Index, sync::Arc};
 
-use arena::{map::ArenaMap, Arena};
 use base_db::CrateId;
 use cfg::CfgOptions;
 use drop_bomb::DropBomb;
@@ -17,6 +16,7 @@ use hir_expand::{
     ast_id_map::AstIdMap, diagnostics::DiagnosticSink, hygiene::Hygiene, AstId, ExpandResult,
     HirFileId, InFile, MacroDefId,
 };
+use la_arena::{map::ArenaMap, Arena};
 use rustc_hash::FxHashMap;
 use syntax::{ast, AstNode, AstPtr};
 use test_utils::mark;
diff --git a/crates/hir_def/src/body/lower.rs b/crates/hir_def/src/body/lower.rs
index 3dc33f248..27575c537 100644
--- a/crates/hir_def/src/body/lower.rs
+++ b/crates/hir_def/src/body/lower.rs
@@ -3,13 +3,13 @@
 
 use std::{any::type_name, sync::Arc};
 
-use arena::Arena;
 use either::Either;
 use hir_expand::{
     hygiene::Hygiene,
     name::{name, AsName, Name},
     ExpandError, HirFileId, MacroDefId, MacroDefKind,
 };
+use la_arena::Arena;
 use rustc_hash::FxHashMap;
 use syntax::{
     ast::{
diff --git a/crates/hir_def/src/body/scope.rs b/crates/hir_def/src/body/scope.rs
index 065785da7..49f1427b4 100644
--- a/crates/hir_def/src/body/scope.rs
+++ b/crates/hir_def/src/body/scope.rs
@@ -1,8 +1,8 @@
 //! Name resolution for expressions.
 use std::sync::Arc;
 
-use arena::{Arena, Idx};
 use hir_expand::name::Name;
+use la_arena::{Arena, Idx};
 use rustc_hash::FxHashMap;
 
 use crate::{
diff --git a/crates/hir_def/src/db.rs b/crates/hir_def/src/db.rs
index d3bf5b34c..0506a7274 100644
--- a/crates/hir_def/src/db.rs
+++ b/crates/hir_def/src/db.rs
@@ -1,9 +1,9 @@
 //! Defines database & queries for name resolution.
 use std::sync::Arc;
 
-use arena::map::ArenaMap;
 use base_db::{salsa, CrateId, SourceDatabase, Upcast};
 use hir_expand::{db::AstDatabase, HirFileId};
+use la_arena::map::ArenaMap;
 use syntax::SmolStr;
 
 use crate::{
diff --git a/crates/hir_def/src/expr.rs b/crates/hir_def/src/expr.rs
index 76f5721e5..af01d32dc 100644
--- a/crates/hir_def/src/expr.rs
+++ b/crates/hir_def/src/expr.rs
@@ -12,8 +12,8 @@
 //!
 //! See also a neighboring `body` module.
 
-use arena::{Idx, RawId};
 use hir_expand::name::Name;
+use la_arena::{Idx, RawId};
 use syntax::ast::RangeOp;
 
 use crate::{
diff --git a/crates/hir_def/src/generics.rs b/crates/hir_def/src/generics.rs
index 9b5b886c2..75eab791a 100644
--- a/crates/hir_def/src/generics.rs
+++ b/crates/hir_def/src/generics.rs
@@ -4,13 +4,13 @@
 //! in rustc.
 use std::sync::Arc;
 
-use arena::{map::ArenaMap, Arena};
 use base_db::FileId;
 use either::Either;
 use hir_expand::{
     name::{name, AsName, Name},
     InFile,
 };
+use la_arena::{map::ArenaMap, Arena};
 use syntax::ast::{self, GenericParamsOwner, NameOwner, TypeBoundsOwner};
 
 use crate::{
diff --git a/crates/hir_def/src/item_tree.rs b/crates/hir_def/src/item_tree.rs
index b6f510731..91e42aa0d 100644
--- a/crates/hir_def/src/item_tree.rs
+++ b/crates/hir_def/src/item_tree.rs
@@ -11,7 +11,6 @@ use std::{
     sync::Arc,
 };
 
-use arena::{Arena, Idx, RawId};
 use ast::{AstNode, NameOwner, StructKind};
 use base_db::CrateId;
 use either::Either;
@@ -21,6 +20,7 @@ use hir_expand::{
     name::{name, AsName, Name},
     HirFileId, InFile,
 };
+use la_arena::{Arena, Idx, RawId};
 use rustc_hash::FxHashMap;
 use smallvec::SmallVec;
 use syntax::{ast, match_ast};
diff --git a/crates/hir_def/src/lib.rs b/crates/hir_def/src/lib.rs
index 211cb2faf..08ed920c6 100644
--- a/crates/hir_def/src/lib.rs
+++ b/crates/hir_def/src/lib.rs
@@ -52,12 +52,12 @@ mod test_db;
 
 use std::hash::{Hash, Hasher};
 
-use arena::Idx;
 use base_db::{impl_intern_key, salsa, CrateId};
 use hir_expand::{
     ast_id_map::FileAstId, eager::expand_eager_macro, hygiene::Hygiene, AstId, HirFileId, InFile,
     MacroCallId, MacroCallKind, MacroDefId, MacroDefKind,
 };
+use la_arena::Idx;
 use syntax::ast;
 
 use crate::builtin_type::BuiltinType;
diff --git a/crates/hir_def/src/nameres.rs b/crates/hir_def/src/nameres.rs
index 5682e122d..50acc3f54 100644
--- a/crates/hir_def/src/nameres.rs
+++ b/crates/hir_def/src/nameres.rs
@@ -56,9 +56,9 @@ mod tests;
 
 use std::sync::Arc;
 
-use arena::Arena;
 use base_db::{CrateId, Edition, FileId};
 use hir_expand::{diagnostics::DiagnosticSink, name::Name, InFile};
+use la_arena::Arena;
 use rustc_hash::FxHashMap;
 use stdx::format_to;
 use syntax::ast;
diff --git a/crates/hir_def/src/nameres/collector.rs b/crates/hir_def/src/nameres/collector.rs
index f027fd48d..0cd61698c 100644
--- a/crates/hir_def/src/nameres/collector.rs
+++ b/crates/hir_def/src/nameres/collector.rs
@@ -1469,8 +1469,8 @@ impl ModCollector<'_, '_> {
 #[cfg(test)]
 mod tests {
     use crate::{db::DefDatabase, test_db::TestDB};
-    use arena::Arena;
     use base_db::{fixture::WithFixture, SourceDatabase};
+    use la_arena::Arena;
 
     use super::*;
 
diff --git a/crates/hir_def/src/src.rs b/crates/hir_def/src/src.rs
index f67244b46..eb29265d9 100644
--- a/crates/hir_def/src/src.rs
+++ b/crates/hir_def/src/src.rs
@@ -1,7 +1,7 @@
 //! Utilities for mapping between hir IDs and the surface syntax.
 
-use arena::map::ArenaMap;
 use hir_expand::InFile;
+use la_arena::map::ArenaMap;
 
 use crate::{db::DefDatabase, item_tree::ItemTreeNode, AssocItemLoc, ItemLoc};
 
diff --git a/crates/hir_def/src/trace.rs b/crates/hir_def/src/trace.rs
index fd64e7018..0a9beae8e 100644
--- a/crates/hir_def/src/trace.rs
+++ b/crates/hir_def/src/trace.rs
@@ -9,7 +9,7 @@
 //! absolute offsets. The `Trace` structure (inspired, at least in name, by
 //! Kotlin's `BindingTrace`) allows use the same code to compute both
 //! projections.
-use arena::{map::ArenaMap, Arena, Idx, RawId};
+use la_arena::{map::ArenaMap, Arena, Idx, RawId};
 
 pub(crate) struct Trace<T, V> {
     arena: Option<Arena<T>>,
diff --git a/crates/hir_expand/Cargo.toml b/crates/hir_expand/Cargo.toml
index 9fad2ab94..b535a3d4f 100644
--- a/crates/hir_expand/Cargo.toml
+++ b/crates/hir_expand/Cargo.toml
@@ -13,8 +13,8 @@ doctest = false
 log = "0.4.8"
 either = "1.5.3"
 rustc-hash = "1.0.0"
+la-arena = "0.1.0"
 
-arena = { path = "../arena", version = "0.0.0" }
 base_db = { path = "../base_db", version = "0.0.0" }
 syntax = { path = "../syntax", version = "0.0.0" }
 parser = { path = "../parser", version = "0.0.0" }
diff --git a/crates/hir_expand/src/ast_id_map.rs b/crates/hir_expand/src/ast_id_map.rs
index f63629b30..f4f6e11fd 100644
--- a/crates/hir_expand/src/ast_id_map.rs
+++ b/crates/hir_expand/src/ast_id_map.rs
@@ -12,7 +12,7 @@ use std::{
     marker::PhantomData,
 };
 
-use arena::{Arena, Idx};
+use la_arena::{Arena, Idx};
 use syntax::{ast, AstNode, AstPtr, SyntaxNode, SyntaxNodePtr};
 
 /// `AstId` points to an AST node in a specific file.
diff --git a/crates/hir_ty/Cargo.toml b/crates/hir_ty/Cargo.toml
index b0a453961..436c1405b 100644
--- a/crates/hir_ty/Cargo.toml
+++ b/crates/hir_ty/Cargo.toml
@@ -20,11 +20,11 @@ scoped-tls = "1"
 chalk-solve = { version = "0.47", default-features = false }
 chalk-ir = "0.47"
 chalk-recursive = "0.47"
+la-arena = "0.1.0"
 
 stdx = { path = "../stdx", version = "0.0.0" }
 hir_def = { path = "../hir_def", version = "0.0.0" }
 hir_expand = { path = "../hir_expand", version = "0.0.0" }
-arena = { path = "../arena", version = "0.0.0" }
 base_db = { path = "../base_db", version = "0.0.0" }
 profile = { path = "../profile", version = "0.0.0" }
 syntax = { path = "../syntax", version = "0.0.0" }
diff --git a/crates/hir_ty/src/db.rs b/crates/hir_ty/src/db.rs
index f3567c49e..b0e2a3b7d 100644
--- a/crates/hir_ty/src/db.rs
+++ b/crates/hir_ty/src/db.rs
@@ -2,12 +2,12 @@
 
 use std::sync::Arc;
 
-use arena::map::ArenaMap;
 use base_db::{impl_intern_key, salsa, CrateId, Upcast};
 use hir_def::{
     db::DefDatabase, expr::ExprId, ConstParamId, DefWithBodyId, FunctionId, GenericDefId, ImplId,
     LocalFieldId, TypeParamId, VariantId,
 };
+use la_arena::map::ArenaMap;
 
 use crate::{
     method_resolution::{InherentImpls, TraitImpls},
diff --git a/crates/hir_ty/src/diagnostics/match_check.rs b/crates/hir_ty/src/diagnostics/match_check.rs
index 61c47eec8..fbe760c39 100644
--- a/crates/hir_ty/src/diagnostics/match_check.rs
+++ b/crates/hir_ty/src/diagnostics/match_check.rs
@@ -218,13 +218,13 @@
 //!   ```
 use std::{iter, sync::Arc};
 
-use arena::Idx;
 use hir_def::{
     adt::VariantData,
     body::Body,
     expr::{Expr, Literal, Pat, PatId},
     AdtId, EnumVariantId, StructId, VariantId,
 };
+use la_arena::Idx;
 use smallvec::{smallvec, SmallVec};
 
 use crate::{db::HirDatabase, ApplicationTy, InferenceResult, Ty, TypeCtor};
diff --git a/crates/hir_ty/src/infer.rs b/crates/hir_ty/src/infer.rs
index a14d67c06..46a806b9a 100644
--- a/crates/hir_ty/src/infer.rs
+++ b/crates/hir_ty/src/infer.rs
@@ -18,7 +18,6 @@ use std::mem;
 use std::ops::Index;
 use std::sync::Arc;
 
-use arena::map::ArenaMap;
 use hir_def::{
     body::Body,
     data::{ConstData, FunctionData, StaticData},
@@ -31,6 +30,7 @@ use hir_def::{
     TypeAliasId, VariantId,
 };
 use hir_expand::{diagnostics::DiagnosticSink, name::name};
+use la_arena::map::ArenaMap;
 use rustc_hash::FxHashMap;
 use stdx::impl_from;
 use syntax::SmolStr;
diff --git a/crates/hir_ty/src/lower.rs b/crates/hir_ty/src/lower.rs
index 9594cce8b..68d16f89a 100644
--- a/crates/hir_ty/src/lower.rs
+++ b/crates/hir_ty/src/lower.rs
@@ -7,7 +7,6 @@
 //! This usually involves resolving names, collecting generic arguments etc.
 use std::{iter, sync::Arc};
 
-use arena::map::ArenaMap;
 use base_db::CrateId;
 use hir_def::{
     adt::StructKind,
@@ -21,6 +20,7 @@ use hir_def::{
     TypeAliasId, TypeParamId, UnionId, VariantId,
 };
 use hir_expand::name::Name;
+use la_arena::map::ArenaMap;
 use smallvec::SmallVec;
 use stdx::impl_from;
 use test_utils::mark;
diff --git a/crates/profile/Cargo.toml b/crates/profile/Cargo.toml
index 4951f1835..096233a09 100644
--- a/crates/profile/Cargo.toml
+++ b/crates/profile/Cargo.toml
@@ -13,8 +13,7 @@ doctest = false
 once_cell = "1.3.1"
 cfg-if = "1"
 libc = "0.2.73"
-
-arena = { path = "../arena", version = "0.0.0" }
+la-arena = "0.1.0"
 
 [target.'cfg(target_os = "linux")'.dependencies]
 perf-event = "0.4"
diff --git a/crates/profile/src/tree.rs b/crates/profile/src/tree.rs
index 3fac1f36c..62f0c30b5 100644
--- a/crates/profile/src/tree.rs
+++ b/crates/profile/src/tree.rs
@@ -1,7 +1,7 @@
 //! A simple tree implementation which tries to not allocate all over the place.
 use std::ops;
 
-use arena::Arena;
+use la_arena::Arena;
 
 #[derive(Default)]
 pub(crate) struct Tree<T> {
@@ -9,7 +9,7 @@ pub(crate) struct Tree<T> {
     current_path: Vec<(Idx<T>, Option<Idx<T>>)>,
 }
 
-pub(crate) type Idx<T> = arena::Idx<Node<T>>;
+pub(crate) type Idx<T> = la_arena::Idx<Node<T>>;
 
 impl<T> Tree<T> {
     pub(crate) fn start(&mut self)
diff --git a/crates/project_model/Cargo.toml b/crates/project_model/Cargo.toml
index 855fb83ea..51e7a7070 100644
--- a/crates/project_model/Cargo.toml
+++ b/crates/project_model/Cargo.toml
@@ -17,8 +17,8 @@ serde = { version = "1.0.106", features = ["derive"] }
 serde_json = "1.0.48"
 anyhow = "1.0.26"
 itertools = "0.10.0"
+la-arena = "0.1.0"
 
-arena = { path = "../arena", version = "0.0.0" }
 cfg = { path = "../cfg", version = "0.0.0" }
 base_db = { path = "../base_db", version = "0.0.0" }
 toolchain = { path = "../toolchain", version = "0.0.0" }
diff --git a/crates/project_model/src/cargo_workspace.rs b/crates/project_model/src/cargo_workspace.rs
index a1ab9c6db..c0ed37fc1 100644
--- a/crates/project_model/src/cargo_workspace.rs
+++ b/crates/project_model/src/cargo_workspace.rs
@@ -10,10 +10,10 @@ use std::{
 };
 
 use anyhow::{Context, Result};
-use arena::{Arena, Idx};
 use base_db::Edition;
 use cargo_metadata::{BuildScript, CargoOpt, Message, MetadataCommand, PackageId};
 use itertools::Itertools;
+use la_arena::{Arena, Idx};
 use paths::{AbsPath, AbsPathBuf};
 use rustc_hash::FxHashMap;
 use stdx::JodChild;
diff --git a/crates/project_model/src/sysroot.rs b/crates/project_model/src/sysroot.rs
index 95b622715..ff44dae4a 100644
--- a/crates/project_model/src/sysroot.rs
+++ b/crates/project_model/src/sysroot.rs
@@ -7,7 +7,7 @@
 use std::{convert::TryFrom, env, ops, path::PathBuf, process::Command};
 
 use anyhow::{format_err, Result};
-use arena::{Arena, Idx};
+use la_arena::{Arena, Idx};
 use paths::{AbsPath, AbsPathBuf};
 
 use crate::utf8_stdout;