From 8ca7aac3eb51e4ca3a3ae48659f88e8f3dea380b Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Thu, 21 Mar 2024 10:28:52 -0400
Subject: [PATCH] Add tests for shortcomings of associated type bounds

---
 .../cant-see-copy-bound-from-child-rigid-2.rs  | 18 ++++++++++++++++++
 ...nt-see-copy-bound-from-child-rigid-2.stderr | 13 +++++++++++++
 .../cant-see-copy-bound-from-child-rigid.rs    | 18 ++++++++++++++++++
 ...cant-see-copy-bound-from-child-rigid.stderr | 14 ++++++++++++++
 4 files changed, 63 insertions(+)
 create mode 100644 tests/ui/associated-type-bounds/cant-see-copy-bound-from-child-rigid-2.rs
 create mode 100644 tests/ui/associated-type-bounds/cant-see-copy-bound-from-child-rigid-2.stderr
 create mode 100644 tests/ui/associated-type-bounds/cant-see-copy-bound-from-child-rigid.rs
 create mode 100644 tests/ui/associated-type-bounds/cant-see-copy-bound-from-child-rigid.stderr

diff --git a/tests/ui/associated-type-bounds/cant-see-copy-bound-from-child-rigid-2.rs b/tests/ui/associated-type-bounds/cant-see-copy-bound-from-child-rigid-2.rs
new file mode 100644
index 0000000000000..1768b006622e2
--- /dev/null
+++ b/tests/ui/associated-type-bounds/cant-see-copy-bound-from-child-rigid-2.rs
@@ -0,0 +1,18 @@
+trait Id {
+    type This: ?Sized;
+}
+impl<T: ?Sized> Id for T {
+    type This = T;
+}
+
+trait Trait {
+    type Assoc: Id<This: Copy>;
+}
+
+// We can't see use the `T::Assoc::This: Copy` bound to prove `T::Assoc: Copy`
+fn foo<T: Trait>(x: T::Assoc) -> (T::Assoc, T::Assoc) {
+    (x, x)
+    //~^ ERROR use of moved value
+}
+
+fn main() {}
diff --git a/tests/ui/associated-type-bounds/cant-see-copy-bound-from-child-rigid-2.stderr b/tests/ui/associated-type-bounds/cant-see-copy-bound-from-child-rigid-2.stderr
new file mode 100644
index 0000000000000..cd0e026905c9a
--- /dev/null
+++ b/tests/ui/associated-type-bounds/cant-see-copy-bound-from-child-rigid-2.stderr
@@ -0,0 +1,13 @@
+error[E0382]: use of moved value: `x`
+  --> $DIR/cant-see-copy-bound-from-child-rigid-2.rs:14:9
+   |
+LL | fn foo<T: Trait>(x: T::Assoc) -> (T::Assoc, T::Assoc) {
+   |                  - move occurs because `x` has type `<T as Trait>::Assoc`, which does not implement the `Copy` trait
+LL |     (x, x)
+   |      -  ^ value used here after move
+   |      |
+   |      value moved here
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0382`.
diff --git a/tests/ui/associated-type-bounds/cant-see-copy-bound-from-child-rigid.rs b/tests/ui/associated-type-bounds/cant-see-copy-bound-from-child-rigid.rs
new file mode 100644
index 0000000000000..6b3fd7e898d18
--- /dev/null
+++ b/tests/ui/associated-type-bounds/cant-see-copy-bound-from-child-rigid.rs
@@ -0,0 +1,18 @@
+trait Id {
+    type This: ?Sized;
+}
+
+trait Trait {
+    type Assoc: Id<This: Copy>;
+}
+
+// We can't see use the `T::Assoc::This: Copy` bound to prove `T::Assoc: Copy`
+fn foo<T: Trait>(x: T::Assoc) -> (T::Assoc, T::Assoc)
+where
+    T::Assoc: Id<This = T::Assoc>,
+{
+    (x, x)
+    //~^ ERROR use of moved value
+}
+
+fn main() {}
diff --git a/tests/ui/associated-type-bounds/cant-see-copy-bound-from-child-rigid.stderr b/tests/ui/associated-type-bounds/cant-see-copy-bound-from-child-rigid.stderr
new file mode 100644
index 0000000000000..3ed73918de313
--- /dev/null
+++ b/tests/ui/associated-type-bounds/cant-see-copy-bound-from-child-rigid.stderr
@@ -0,0 +1,14 @@
+error[E0382]: use of moved value: `x`
+  --> $DIR/cant-see-copy-bound-from-child-rigid.rs:14:9
+   |
+LL | fn foo<T: Trait>(x: T::Assoc) -> (T::Assoc, T::Assoc)
+   |                  - move occurs because `x` has type `<T as Trait>::Assoc`, which does not implement the `Copy` trait
+...
+LL |     (x, x)
+   |      -  ^ value used here after move
+   |      |
+   |      value moved here
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0382`.