Add @weiznich's regression test

Author: Aaron1011

src/test/ui/consts/issue-68264-overflow.rs

@@ -0,0 +1,43 @@
+// check-pass
+// compile-flags: --emit=mir,link
+// Regression test for issue #68264
+// Checks that we don't encounter overflow
+// when running const-prop on functions with
+// complicated bounds
+pub trait Query {}
+
+pub trait AsQuery {
+    type Query: Query;
+}
+pub trait Table: AsQuery + Sized {}
+
+pub trait LimitDsl {
+    type Output;
+}
+
+pub(crate) trait LoadQuery<Conn, U>: RunQueryDsl<Conn> {}
+
+impl<T: Query> AsQuery for T {
+    type Query = Self;
+}
+
+impl<T> LimitDsl for T
+where
+    T: Table,
+    T::Query: LimitDsl,
+{
+    type Output = <T::Query as LimitDsl>::Output;
+}
+
+pub(crate) trait RunQueryDsl<Conn>: Sized {
+    fn first<U>(self, _conn: &Conn) -> U
+    where
+        Self: LimitDsl,
+        Self::Output: LoadQuery<Conn, U>,
+    {
+        // Overflow is caused by this function body
+        unimplemented!()
+    }
+}
+
+fn main() {}