unikernel/duniverse/dune_/test/blackbox-tests/test-cases/virtual-libraries/github2896.t

@@ -0,0 +1,42 @@
+Reproduction of the issue in #2896
+
+We have a dependency cycle of the form impl <- lib <- vlib
+
+where vlib is a virtual library, and impl implements this library.
+
+  $ echo "(lang dune 2.3)" > dune-project
+  $ mkdir vlib impl lib
+  $ touch impl/vlib.ml
+  $ echo "val run : unit -> unit" > vlib/vlib.mli
+  $ cat >vlib/dune <<EOF
+  > (library (name vlib) (virtual_modules vlib))
+  > EOF
+  $ echo "let bar () = Vlib.run ();;" > lib/lib.ml
+  $ cat >lib/dune <<EOF
+  > (library (name lib) (libraries vlib))
+  > EOF
+  $ echo "let run () = Lib.bar ();;" > impl/vlib.ml
+  $ cat >impl/dune <<EOF
+  > (library (name impl) (implements vlib) (libraries lib))
+  > EOF
+  $ dune build @all
+  Error: Library "vlib" was pulled in.
+  -> required by library "lib" in _build/default/lib
+  -> required by library "impl" in _build/default/impl
+  -> required by _build/default/impl/.impl.objs/byte/vlib.cmo
+  -> required by _build/default/impl/impl.cma
+  -> required by alias impl/all
+  [1]
+
+The implementation impl was built, but it's not usable:
+
+  $ echo 'Vlib.run ()' > foo.ml
+  $ echo "(executable (name foo) (libraries impl))" > dune
+  $ dune exec ./foo.exe
+  Error: Library "vlib" was pulled in.
+  -> required by library "lib" in _build/default/lib
+  -> required by library "impl" in _build/default/impl
+  -> required by executable foo in dune:1
+  -> required by _build/default/.foo.eobjs/native/dune__exe__Foo.cmx
+  -> required by _build/default/foo.exe
+  [1]