Merge #4159

4159: For associated type shorthand (T::Item), use the substs from the where clause r=matklad a=flodiebold

So e.g. if we have `fn foo<T: SomeTrait<u32>>() -> T::Item`, we want to lower that to `<T as SomeTrait<u32>>::Item` and not `<T as SomeTrait<_>>::Item`.

Co-authored-by: Florian Diebold <[email protected]>

1 files changed, 12 insertions, 0 deletions

diff --git a/crates/ra_hir_ty/src/lib.rs b/crates/ra_hir_ty/src/lib.rs
index 279c06d65..a8ef32ec5 100644
--- a/crates/ra_hir_ty/src/lib.rs
+++ b/crates/ra_hir_ty/src/lib.rs
@@ -487,6 +487,18 @@ impl<T> Binders<T> {
     pub fn new(num_binders: usize, value: T) -> Self {
         Self { num_binders, value }
     }
+
+    pub fn as_ref(&self) -> Binders<&T> {
+        Binders { num_binders: self.num_binders, value: &self.value }
+    }
+
+    pub fn map<U>(self, f: impl FnOnce(T) -> U) -> Binders<U> {
+        Binders { num_binders: self.num_binders, value: f(self.value) }
+    }
+
+    pub fn filter_map<U>(self, f: impl FnOnce(T) -> Option<U>) -> Option<Binders<U>> {
+        Some(Binders { num_binders: self.num_binders, value: f(self.value)? })
+    }
 }
 
 impl<T: Clone> Binders<&T> {