  $ ocamlc_where="$(ocamlc -where)"
  $ export BUILD_PATH_PREFIX_MAP="/OCAMLC_WHERE=$ocamlc_where:$BUILD_PATH_PREFIX_MAP"
  $ unset OPAMCONFIRMLEVEL

We call `$(opam switch show)` so that this test always uses an existing switch

  $ cat >dune-workspace <<EOF
  > (lang dune 2.0)
  > (context (default))
  > (context
  > (opam
  >  (name cross)
  >  (switch $(opam switch show))
  >  (merlin)))
  > EOF

  $ dune build

  $ ls -a _build/cross/.merlin-conf
  .
  ..
  lib-foo

  $ dune ocaml merlin dump-config "$PWD"
  Foo: _build/cross/foo
  ((INDEX $TESTCASE_ROOT/_build/cross/.foo.objs/cctx.ocaml-index) (STDLIB /OCAMLC_WHERE) (SOURCE_ROOT $TESTCASE_ROOT) (EXCLUDE_QUERY_DIR) (B $TESTCASE_ROOT/_build/cross/.foo.objs/byte) (S $TESTCASE_ROOT) (FLG (-w @1..3@5..28@30..39@43@46..47@49..57@61..62-40 -strict-sequence -strict-formats -short-paths -keep-locs -g)) (UNIT_NAME foo))
  Foo: _build/cross/foo.ml
  ((INDEX $TESTCASE_ROOT/_build/cross/.foo.objs/cctx.ocaml-index) (STDLIB /OCAMLC_WHERE) (SOURCE_ROOT $TESTCASE_ROOT) (EXCLUDE_QUERY_DIR) (B $TESTCASE_ROOT/_build/cross/.foo.objs/byte) (S $TESTCASE_ROOT) (FLG (-w @1..3@5..28@30..39@43@46..47@49..57@61..62-40 -strict-sequence -strict-formats -short-paths -keep-locs -g)) (UNIT_NAME foo))
