chore: remove dependency on generational-arena

compiler/noirc_frontend/src/hir/def_map/mod.rs

@@ -31,7 +31,7 @@ pub struct LocalModuleId(pub Index);
 
 impl LocalModuleId {
     pub fn dummy_id() -> LocalModuleId {
-        LocalModuleId(Index::from_raw_parts(std::usize::MAX, std::u64::MAX))
+        LocalModuleId(Index { ix: std::usize::MAX })
     }
 }
 

compiler/noirc_frontend/src/hir/type_check/mod.rs

@@ -454,7 +454,7 @@ mod test {
         }
 
         fn local_module_id(&self) -> LocalModuleId {
-            LocalModuleId(arena::Index::from_raw_parts(0, 0))
+            LocalModuleId(arena::Index { ix: 0 })
         }
 
         fn module_id(&self) -> ModuleId {
@@ -505,7 +505,7 @@ mod test {
         let mut def_maps = BTreeMap::new();
         let file = FileId::default();
 
-        let mut modules = arena::Arena::new();
+        let mut modules = arena::Arena::default();
         let location = Location::new(Default::default(), file);
         modules.insert(ModuleData::new(None, location, false));
 

compiler/noirc_frontend/src/node_interner.rs

@@ -242,7 +242,7 @@ impl DefinitionId {
 
 impl From<DefinitionId> for Index {
     fn from(id: DefinitionId) -> Self {
-        Index::from_raw_parts(id.0, u64::MAX)
+        Index { ix: id.0 }
     }
 }
 
@@ -254,7 +254,7 @@ impl StmtId {
     // This can be anything, as the program will ultimately fail
     // after resolution
     pub fn dummy_id() -> StmtId {
-        StmtId(Index::from_raw_parts(std::usize::MAX, 0))
+        StmtId(Index { ix: std::usize::MAX })
     }
 }
 
@@ -263,7 +263,7 @@ pub struct ExprId(Index);
 
 impl ExprId {
     pub fn empty_block_id() -> ExprId {
-        ExprId(Index::from_raw_parts(0, 0))
+        ExprId(Index { ix: 0 })
     }
 }
 #[derive(Debug, Eq, PartialEq, Hash, Copy, Clone)]
@@ -274,7 +274,7 @@ impl FuncId {
     // This can be anything, as the program will ultimately fail
     // after resolution
     pub fn dummy_id() -> FuncId {
-        FuncId(Index::from_raw_parts(std::usize::MAX, 0))
+        FuncId(Index { ix: std::usize::MAX })
     }
 }
 
@@ -352,7 +352,7 @@ macro_rules! partialeq {
     ($id_type:ty) => {
         impl PartialEq<usize> for &$id_type {
             fn eq(&self, other: &usize) -> bool {
-                let (index, _) = self.0.into_raw_parts();
+                let index = self.0.ix;
                 index == *other
             }
         }

compiler/utils/arena/Cargo.toml

@@ -4,8 +4,3 @@ version.workspace = true
 authors.workspace = true
 edition.workspace = true
 license.workspace = true
-
-# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
-
-[dependencies]
-generational-arena = "0.2.8"

compiler/utils/arena/src/lib.rs

@@ -3,5 +3,52 @@
 #![warn(unreachable_pub)]
 #![warn(clippy::semicolon_if_nothing_returned)]
 
-// For now we use a wrapper around generational-arena
-pub use generational_arena::{Arena, Index};
+#[derive(Clone, Copy, Debug, Eq, Ord, PartialEq, PartialOrd, Hash)]
+pub struct Index {
+    pub ix: usize,
+}
+
+#[derive(Debug, Eq, PartialEq, Hash, Clone)]
+pub struct Arena<T> {
+    vec: Vec<T>,
+}
+
+impl<T> Default for Arena<T> {
+    fn default() -> Self {
+        Self { vec: Vec::new() }
+    }
+}
+
+impl<T> core::ops::Index<Index> for Arena<T> {
+    type Output = T;
+
+    fn index(&self, index: Index) -> &Self::Output {
+        self.vec.index(index.ix)
+    }
+}
+
+impl<T> core::ops::IndexMut<Index> for Arena<T> {
+    fn index_mut(&mut self, index: Index) -> &mut Self::Output {
+        self.vec.index_mut(index.ix)
+    }
+}
+
+impl<T> Arena<T> {
+    pub fn insert(&mut self, item: T) -> Index {
+        let ix = self.vec.len();
+        self.vec.push(item);
+        Index { ix }
+    }
+
+    pub fn get(&self, index: Index) -> Option<&T> {
+        self.vec.get(index.ix)
+    }
+
+    pub fn get_mut(&mut self, index: Index) -> Option<&mut T> {
+        self.vec.get_mut(index.ix)
+    }
+
+    pub fn iter(&self) -> impl Iterator<Item = (Index, &T)> {
+        self.vec.iter().enumerate().map(|(ix, item)| (Index { ix }, item))
+    }
+}