Merge #3584

3584: Switch to dynamic dispatch r=matklad a=matklad

Benches are in https://github.com/rust-analyzer/rust-analyzer/issues/1987#issuecomment-598807185

TL;DR: 

* 33% faster release build
* slightly worse/same perf
* no changes for debug build
* slightly smaller binary

cc @flodiebold I genuinely don't know if it is a good idea or not.

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

1 files changed, 14 insertions, 1 deletions

diff --git a/crates/ra_ide_db/src/lib.rs b/crates/ra_ide_db/src/lib.rs
index fc1b19def..4faeefa8d 100644
--- a/crates/ra_ide_db/src/lib.rs
+++ b/crates/ra_ide_db/src/lib.rs
@@ -14,10 +14,11 @@ mod wasm_shims;
 
 use std::sync::Arc;
 
+use hir::db::{AstDatabase, DefDatabase};
 use ra_db::{
     salsa::{self, Database, Durability},
     Canceled, CheckCanceled, CrateId, FileId, FileLoader, FileLoaderDelegate, RelativePath,
-    SourceDatabase, SourceRootId,
+    SourceDatabase, SourceRootId, Upcast,
 };
 use rustc_hash::FxHashMap;
 
@@ -41,6 +42,18 @@ pub struct RootDatabase {
     pub last_gc_check: crate::wasm_shims::Instant,
 }
 
+impl Upcast<dyn AstDatabase> for RootDatabase {
+    fn upcast(&self) -> &(dyn AstDatabase + 'static) {
+        &*self
+    }
+}
+
+impl Upcast<dyn DefDatabase> for RootDatabase {
+    fn upcast(&self) -> &(dyn DefDatabase + 'static) {
+        &*self
+    }
+}
+
 impl FileLoader for RootDatabase {
     fn file_text(&self, file_id: FileId) -> Arc<String> {
         FileLoaderDelegate(self).file_text(file_id)