Merge #3656

3656: Simplify arenas r=matklad a=matklad

At the moment, Arena is paranetrized by two types: index and data. The original motivation was to allow index to be defined in the downstream crate, so that you can add inherent impls to the index. 

However, it seems like we've never actually used that capability, so perhaps we should switch to a generic Index impl? This PR tries this out, switching only `raw.rs` and parts of `hir_def`. 

wdyt?

Co-authored-by: Aleksey Kladov <[email protected]>

1 files changed, 3 insertions, 5 deletions

diff --git a/crates/ra_hir_def/src/body/scope.rs b/crates/ra_hir_def/src/body/scope.rs
index 7c3db8869..4d489f692 100644
--- a/crates/ra_hir_def/src/body/scope.rs
+++ b/crates/ra_hir_def/src/body/scope.rs
@@ -2,7 +2,7 @@
 use std::sync::Arc;
 
 use hir_expand::name::Name;
-use ra_arena::{impl_arena_id, Arena, RawId};
+use ra_arena::{Arena, Idx};
 use rustc_hash::FxHashMap;
 
 use crate::{
@@ -12,13 +12,11 @@ use crate::{
     DefWithBodyId,
 };
 
-#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
-pub struct ScopeId(RawId);
-impl_arena_id!(ScopeId);
+pub type ScopeId = Idx<ScopeData>;
 
 #[derive(Debug, PartialEq, Eq)]
 pub struct ExprScopes {
-    scopes: Arena<ScopeId, ScopeData>,
+    scopes: Arena<ScopeData>,
     scope_by_expr: FxHashMap<ExprId, ScopeId>,
 }