2 files changed, 33 insertions, 0 deletions
diff --git a/lib/spack/spack/concretize.py b/lib/spack/spack/concretize.py
index fbd9a7908b..900009e283 100644
--- a/lib/spack/spack/concretize.py
+++ b/lib/spack/spack/concretize.py
@@ -724,6 +724,24 @@ def concretize_specs_together(*abstract_specs, **kwargs):
     Returns:
         List of concretized specs
     """
+    if spack.config.get('config:concretizer') == 'original':
+        return _concretize_specs_together_original(*abstract_specs, **kwargs)
+    return _concretize_specs_together_new(*abstract_specs, **kwargs)
+
+
+def _concretize_specs_together_new(*abstract_specs, **kwargs):
+    import spack.solver.asp
+    result = spack.solver.asp.solve(abstract_specs)
+
+    if not result.satisfiable:
+        result.print_cores()
+        tty.die("Unsatisfiable spec.")
+
+    opt, i, answer = min(result.answers)
+    return [answer[s.name].copy() for s in abstract_specs]
+
+
+def _concretize_specs_together_original(*abstract_specs, **kwargs):
     def make_concretization_repository(abstract_specs):
         """Returns the path to a temporary repository created to contain
         a fake package that depends on all of the abstract specs.
diff --git a/lib/spack/spack/test/cmd/env.py b/lib/spack/spack/test/cmd/env.py
index 5665b41fac..5ff0f0de9f 100644
--- a/lib/spack/spack/test/cmd/env.py
+++ b/lib/spack/spack/test/cmd/env.py
@@ -2454,3 +2454,18 @@ def test_does_not_rewrite_rel_dev_path_when_keep_relative_is_set(tmpdir):
         print(e.dev_specs)
         assert e.dev_specs['mypkg1']['path'] == '../build_folder'
         assert e.dev_specs['mypkg2']['path'] == '/some/other/path'
+
+
+@pytest.mark.regression('23440')
+def test_custom_version_concretize_together(tmpdir):
+    # Custom versions should be permitted in specs when
+    # concretizing together
+    e = ev.create('custom_version')
+    e.concretization = 'together'
+
+    # Concretize a first time using 'mpich' as the MPI provider
+    e.add('hdf5@myversion')
+    e.add('mpich')
+    e.concretize()
+
+    assert any('hdf5@myversion' in spec for _, spec in e.concretized_specs())