From 2d5d692053590aa173ffebd3d5fc9707dc39ea9f Mon Sep 17 00:00:00 2001
From: Guillaume Gomez <guillaume.gomez@huawei.com>
Date: Tue, 22 Nov 2022 16:02:37 +0100
Subject: [PATCH] Add failing test for projections used as const generic

---
 .../const-generics/projection-as-arg-const.rs | 20 +++++++++++++++++++
 .../projection-as-arg-const.stderr            | 11 ++++++++++
 2 files changed, 31 insertions(+)
 create mode 100644 src/test/ui/const-generics/projection-as-arg-const.rs
 create mode 100644 src/test/ui/const-generics/projection-as-arg-const.stderr

diff --git a/src/test/ui/const-generics/projection-as-arg-const.rs b/src/test/ui/const-generics/projection-as-arg-const.rs
new file mode 100644
index 0000000000000..903548c75db56
--- /dev/null
+++ b/src/test/ui/const-generics/projection-as-arg-const.rs
@@ -0,0 +1,20 @@
+// This is currently not possible to use projections as const generics.
+// More information about this available here:
+// https://github.com/rust-lang/rust/pull/104443#discussion_r1029375633
+
+pub trait Identity {
+    type Identity;
+}
+
+impl<T> Identity for T {
+    type Identity = Self;
+}
+
+pub fn foo<const X: <i32 as Identity>::Identity>() {
+//~^ ERROR
+    assert!(X == 12);
+}
+
+fn main() {
+    foo::<12>();
+}
diff --git a/src/test/ui/const-generics/projection-as-arg-const.stderr b/src/test/ui/const-generics/projection-as-arg-const.stderr
new file mode 100644
index 0000000000000..803ed9c959752
--- /dev/null
+++ b/src/test/ui/const-generics/projection-as-arg-const.stderr
@@ -0,0 +1,11 @@
+error: `<i32 as Identity>::Identity` is forbidden as the type of a const generic parameter
+  --> $DIR/projection-as-arg-const.rs:13:21
+   |
+LL | pub fn foo<const X: <i32 as Identity>::Identity>() {
+   |                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: the only supported types are integers, `bool` and `char`
+   = help: more complex types are supported with `#![feature(adt_const_params)]`
+
+error: aborting due to previous error
+