Allow non-empty ranges 1.1.0:1.1 (#26402)

lib/spack/spack/test/versions.py

@@ -16,7 +16,7 @@
 import spack.package
 import spack.spec
 from spack.util.executable import which
-from spack.version import Version, VersionList, ver
+from spack.version import Version, VersionList, VersionRange, ver
 
 
 def assert_ver_lt(a, b):
@@ -602,3 +602,15 @@ def test_versions_from_git(mock_git_version_info, monkeypatch, mock_packages):
             expected = f.read()
 
         assert str(comparator) == expected
+
+
+def test_version_range_nonempty():
+    assert Version('1.2.9') in VersionRange('1.2.0', '1.2')
+    assert Version('1.1.1') in ver('1.0:1')
+
+
+def test_empty_version_range_raises():
+    with pytest.raises(ValueError):
+        assert VersionRange('2', '1.0')
+    with pytest.raises(ValueError):
+        assert ver('2:1.0')

lib/spack/spack/version.py

@@ -500,7 +500,16 @@ def __init__(self, start, end):
 
         self.start = start
         self.end = end
-        if start and end and end < start:
+
+        # Unbounded ranges are not empty
+        if not start or not end:
+            return
+
+        # Do not allow empty ranges. We have to be careful about lexicographical
+        # ordering of versions here: 1.2 < 1.2.3 lexicographically, but 1.2.3:1.2
+        # means the range [1.2.3, 1.3), which is non-empty.
+        min_len = min(len(start), len(end))
+        if end.up_to(min_len) < start.up_to(min_len):
             raise ValueError("Invalid Version range: %s" % self)
 
     def lowest(self):