Merge #2006

2006: Improvements around `Arc<[T]>` r=matklad a=sinkuu

First commit tries to avoid cloning `Arc<[T]>` to a temporary `Vec` for mutating it, if there are no other strong references. Second commit utilizes [`FromIterator for Arc<[T]>`](https://doc.rust-lang.org/std/sync/struct.Arc.html#impl-FromIterator%3CT%3E) instead of `.collect::<Vec<_>>().into()` to avoid allocation in `From<Vec<T>> for Arc<[T]>`.

Co-authored-by: Shotaro Yamada <[email protected]>

1 files changed, 1 insertions, 2 deletions

diff --git a/crates/ra_hir/src/ty/traits/chalk.rs b/crates/ra_hir/src/ty/traits/chalk.rs
index 9168de709..00aaf65d9 100644
--- a/crates/ra_hir/src/ty/traits/chalk.rs
+++ b/crates/ra_hir/src/ty/traits/chalk.rs
@@ -126,8 +126,7 @@ impl ToChalk for Substs {
                 chalk_ir::Parameter(chalk_ir::ParameterKind::Ty(ty)) => from_chalk(db, ty),
                 chalk_ir::Parameter(chalk_ir::ParameterKind::Lifetime(_)) => unimplemented!(),
             })
-            .collect::<Vec<_>>()
-            .into();
+            .collect();
         Substs(tys)
     }
 }