test: building module artifact targets under (include_subdirs qualified)

test/blackbox-tests/test-cases/include-qualified/module-artifact-targets.t

@@ -0,0 +1,65 @@
+Building a module artifact target (%{cmi:...}, %{cmo:...}, %{cmx:...},
+%{cmt:...}, %{cmti:...}) should work when (include_subdirs qualified) is
+used and two qualified subdirectories contain modules with the same leaf
+name.
+
+  $ make_dune_project 3.7
+
+  $ cat > dune <<EOF
+  > (include_subdirs qualified)
+  > (library (name main) (modes byte native))
+  > EOF
+  $ cat > main.ml <<EOF
+  > let _ = (Sub_a.Group.x, Sub_b.Group.x)
+  > EOF
+
+  $ mkdir sub_a sub_b
+  $ echo 'let x = "a"' > sub_a/group.ml
+  $ echo 'let x = "b"' > sub_b/group.ml
+
+A normal build succeeds:
+
+  $ dune build @check
+
+Asking for any module artifact of a module in the stanza crashes with the
+same internal error:
+
+  $ dune build %{cmi:main} 2>&1 | head -5
+  Internal error! Please report to https://github.com/ocaml/dune/issues,
+  providing the file _build/trace.csexp, if possible. This includes build
+  commands, message logs, and file paths.
+  Description:
+    ("Map.add_exn: key already exists", { key = "Group" })
+  [1]
+
+  $ dune build %{cmo:main} 2>&1 | head -5
+  Internal error! Please report to https://github.com/ocaml/dune/issues,
+  providing the file _build/trace.csexp, if possible. This includes build
+  commands, message logs, and file paths.
+  Description:
+    ("Map.add_exn: key already exists", { key = "Group" })
+  [1]
+
+  $ dune build %{cmx:main} 2>&1 | head -5
+  Internal error! Please report to https://github.com/ocaml/dune/issues,
+  providing the file _build/trace.csexp, if possible. This includes build
+  commands, message logs, and file paths.
+  Description:
+    ("Map.add_exn: key already exists", { key = "Group" })
+  [1]
+
+  $ dune build %{cmt:main} 2>&1 | head -5
+  Internal error! Please report to https://github.com/ocaml/dune/issues,
+  providing the file _build/trace.csexp, if possible. This includes build
+  commands, message logs, and file paths.
+  Description:
+    ("Map.add_exn: key already exists", { key = "Group" })
+  [1]
+
+  $ dune build %{cmti:main} 2>&1 | head -5
+  Internal error! Please report to https://github.com/ocaml/dune/issues,
+  providing the file _build/trace.csexp, if possible. This includes build
+  commands, message logs, and file paths.
+  Description:
+    ("Map.add_exn: key already exists", { key = "Group" })
+  [1]