unikernel/duniverse/dune_/test/blackbox-tests/test-cases/deps-conf-vars/deps-diff.t

@@ -0,0 +1,16 @@
+Deps in diff position. Used to work in 2.9.x
+
+  $ touch foo foo.diff
+  $ cat >dune <<EOF
+  > (rule
+  >  (deps foo)
+  >  (alias foo)
+  >  (action (diff? %{deps} %{deps}.diff)))
+  > EOF
+  $ echo "(lang dune 2.9)" > dune-project
+  $ dune build @foo
+  File "dune", line 4, characters 24-31:
+  4 |  (action (diff? %{deps} %{deps}.diff)))
+                              ^^^^^^^
+  Error: %{deps} isn't allowed in this position.
+  [1]