Implement autoderef for field accesses

1 files changed, 21 insertions, 0 deletions

diff --git a/crates/ra_hir/src/ty/autoderef.rs b/crates/ra_hir/src/ty/autoderef.rs
new file mode 100644
index 000000000..24a386558
--- /dev/null
+++ b/crates/ra_hir/src/ty/autoderef.rs
@@ -0,0 +1,21 @@
+//! In certain situations, rust automatically inserts derefs as necessary: For
+//! example, field accesses `foo.bar` still work when `foo` is actually a
+//! reference to a type with the field `bar`. This is an approximation of the
+//! logic in rustc (which lives in librustc_typeck/check/autoderef.rs).
+
+use ra_syntax::algo::generate;
+
+use crate::HirDatabase;
+use super::Ty;
+
+impl Ty {
+    /// Iterates over the possible derefs of `ty`.
+    pub fn autoderef<'a>(self, db: &'a impl HirDatabase) -> impl Iterator<Item = Ty> + 'a {
+        generate(Some(self), move |ty| ty.autoderef_step(db))
+    }
+
+    fn autoderef_step(&self, _db: &impl HirDatabase) -> Option<Ty> {
+        // TODO Deref::deref
+        self.builtin_deref()
+    }
+}