add test for ice 68875

Fixes #68875

Author: matthiaskrgr

src/test/ui/const-generics/ice-68875.rs

@@ -0,0 +1,11 @@
+// check-fail
+
+struct DataWrapper<'a> {
+    data: &'a [u8; Self::SIZE], //~ ERROR generic `Self` types are currently not permitted in anonymous constants
+}
+
+impl DataWrapper<'_> {
+    const SIZE: usize = 14;
+}
+
+pub fn main() {}

src/test/ui/const-generics/ice-68875.stderr

@@ -0,0 +1,8 @@
+error: generic `Self` types are currently not permitted in anonymous constants
+  --> $DIR/ice-68875.rs:4:20
+   |
+LL |     data: &'a [u8; Self::SIZE],
+   |                    ^^^^
+
+error: aborting due to previous error
+