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, 4 insertions, 0 deletions

diff --git a/crates/ra_db/src/lib.rs b/crates/ra_db/src/lib.rs
index d500d5e85..bac24e218 100644
--- a/crates/ra_db/src/lib.rs
+++ b/crates/ra_db/src/lib.rs
@@ -32,6 +32,10 @@ macro_rules! impl_intern_key {
     };
 }
 
+pub trait Upcast<T: ?Sized> {
+    fn upcast(&self) -> &T;
+}
+
 pub trait CheckCanceled {
     /// Aborts current query if there are pending changes.
     ///