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_project_model/src/sysroot.rs b/crates/ra_project_model/src/sysroot.rs
index 4ac4fa14d..55ff5ad80 100644
--- a/crates/ra_project_model/src/sysroot.rs
+++ b/crates/ra_project_model/src/sysroot.rs
@@ -7,16 +7,14 @@ use std::{
     process::{Command, Output},
 };
 
-use ra_arena::{impl_arena_id, Arena, RawId};
+use ra_arena::{Arena, Idx};
 
 #[derive(Default, Debug, Clone)]
 pub struct Sysroot {
-    crates: Arena<SysrootCrate, SysrootCrateData>,
+    crates: Arena<SysrootCrateData>,
 }
 
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub struct SysrootCrate(RawId);
-impl_arena_id!(SysrootCrate);
+pub type SysrootCrate = Idx<SysrootCrateData>;
 
 #[derive(Debug, Clone)]
 pub struct SysrootCrateData {