From 59b36bcfb5fa50b370869f5073a57d514f59e0c8 Mon Sep 17 00:00:00 2001
From: Dominik Stolz <d.stolz@tum.de>
Date: Tue, 12 Oct 2021 21:50:44 +0200
Subject: [PATCH] Add UI test for the variance of types appearing in consts

---
 .../ui/variance/variance-associated-consts.rs   | 17 +++++++++++++++++
 .../variance/variance-associated-consts.stderr  | 10 ++++++++++
 2 files changed, 27 insertions(+)
 create mode 100644 src/test/ui/variance/variance-associated-consts.rs
 create mode 100644 src/test/ui/variance/variance-associated-consts.stderr

diff --git a/src/test/ui/variance/variance-associated-consts.rs b/src/test/ui/variance/variance-associated-consts.rs
new file mode 100644
index 000000000000..da55bc96244f
--- /dev/null
+++ b/src/test/ui/variance/variance-associated-consts.rs
@@ -0,0 +1,17 @@
+// Test that the variance computation considers types that
+// appear in const expressions to be invariant.
+
+#![feature(rustc_attrs)]
+#![allow(incomplete_features)]
+#![feature(generic_const_exprs)]
+
+trait Trait {
+    const Const: usize;
+}
+
+#[rustc_variance]
+struct Foo<T: Trait> { //~ ERROR [o]
+    field: [u8; <T as Trait>::Const]
+}
+
+fn main() { }
diff --git a/src/test/ui/variance/variance-associated-consts.stderr b/src/test/ui/variance/variance-associated-consts.stderr
new file mode 100644
index 000000000000..d1bf34781dfb
--- /dev/null
+++ b/src/test/ui/variance/variance-associated-consts.stderr
@@ -0,0 +1,10 @@
+error[E0208]: [o]
+  --> $DIR/variance-associated-consts.rs:13:1
+   |
+LL | / struct Foo<T: Trait> {
+LL | |     field: [u8; <T as Trait>::Const]
+LL | | }
+   | |_^
+
+error: aborting due to previous error
+