add test for trait alias projections

1 files changed, 21 insertions, 0 deletions

diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/tests/trait_aliases.rs b/src/tools/rust-analyzer/crates/hir-ty/src/tests/trait_aliases.rs
new file mode 100644
index 00000000000..302ce550b85
--- /dev/null
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/tests/trait_aliases.rs
@@ -0,0 +1,21 @@
+use crate::tests::check_types;
+
+#[test]
+fn projection() {
+    check_types(
+        r#"
+#![feature(trait_alias)]
+
+pub trait A {
+    type Output;
+}
+
+pub trait B = A<Output = u32>;
+
+pub fn a<T: B>(x: T::Output) {
+    x;
+//  ^ u32
+}
+"#,
+    );
+}