diff --git a/src/test/ui/associated-types/issue-47814.rs b/src/test/ui/associated-types/issue-47814.rs
new file mode 100644
index 000000000000..90e8a3bc2f2f
--- /dev/null
+++ b/src/test/ui/associated-types/issue-47814.rs
@@ -0,0 +1,13 @@
+struct ArpIPv4<'a> {
+    s: &'a u8
+}
+
+impl<'a> ArpIPv4<'a> {
+    const LENGTH: usize = 20;
+
+    pub fn to_buffer() -> [u8; Self::LENGTH] { //~ ERROR generic `Self` types are currently not permitted in anonymous constants
+        unimplemented!()
+    }
+}
+
+pub fn main() {}
diff --git a/src/test/ui/associated-types/issue-47814.stderr b/src/test/ui/associated-types/issue-47814.stderr
new file mode 100644
index 000000000000..2e4ddb81166b
--- /dev/null
+++ b/src/test/ui/associated-types/issue-47814.stderr
@@ -0,0 +1,14 @@
+error: generic `Self` types are currently not permitted in anonymous constants
+  --> $DIR/issue-47814.rs:8:32
+   |
+LL |     pub fn to_buffer() -> [u8; Self::LENGTH] {
+   |                                ^^^^
+   |
+note: not a concrete type
+  --> $DIR/issue-47814.rs:5:10
+   |
+LL | impl<'a> ArpIPv4<'a> {
+   |          ^^^^^^^^^^^
+
+error: aborting due to previous error
+