Fix compatible version specifier incorrectly strip trailing '0' (#493)

Co-authored-by: Tzu-ping Chung <uranusjr@gmail.com>
Co-authored-by: Pradyun Gedam <pradyunsg@gmail.com>
Co-authored-by: Brett Cannon <brett@python.org>

packaging/specifiers.py

@@ -119,7 +119,11 @@ def __str__(self) -> str:
 
     @property
     def _canonical_spec(self) -> Tuple[str, str]:
-        return self._spec[0], canonicalize_version(self._spec[1])
+        canonical_version = canonicalize_version(
+            self._spec[1],
+            strip_trailing_zero=(self._spec[0] != "~="),
+        )
+        return self._spec[0], canonical_version
 
     def __hash__(self) -> int:
         return hash(self._canonical_spec)

packaging/utils.py

@@ -35,7 +35,9 @@ def canonicalize_name(name: str) -> NormalizedName:
     return cast(NormalizedName, value)
 
 
-def canonicalize_version(version: Union[Version, str]) -> str:
+def canonicalize_version(
+    version: Union[Version, str], *, strip_trailing_zero: bool = True
+) -> str:
     """
     This is very similar to Version.__str__, but has one subtle difference
     with the way it handles the release segment.
@@ -56,8 +58,11 @@ def canonicalize_version(version: Union[Version, str]) -> str:
         parts.append(f"{parsed.epoch}!")
 
     # Release segment
-    # NB: This strips trailing '.0's to normalize
-    parts.append(re.sub(r"(\.0)+$", "", ".".join(str(x) for x in parsed.release)))
+    release_segment = ".".join(str(x) for x in parsed.release)
+    if strip_trailing_zero:
+        # NB: This strips trailing '.0's to normalize
+        release_segment = re.sub(r"(\.0)+$", "", release_segment)
+    parts.append(release_segment)
 
     # Pre-release
     if parsed.pre is not None:

tests/test_specifiers.py

@@ -630,6 +630,12 @@ def test_iteration(self, spec, expected_items):
         items = {str(item) for item in spec}
         assert items == set(expected_items)
 
+    def test_specifier_equal_for_compatible_operator(self):
+        assert Specifier("~=1.18.0") != Specifier("~=1.18")
+
+    def test_specifier_hash_for_compatible_operator(self):
+        assert hash(Specifier("~=1.18.0")) != hash(Specifier("~=1.18"))
+
 
 class TestLegacySpecifier:
     def test_legacy_specifier_is_deprecated(self):
@@ -996,3 +1002,8 @@ def test_comparison_non_specifier(self):
     )
     def test_comparison_ignores_local(self, version, specifier, expected):
         assert (Version(version) in SpecifierSet(specifier)) == expected
+
+    def test_contains_with_compatible_operator(self):
+        combination = SpecifierSet("~=1.18.0") & SpecifierSet("~=1.18")
+        assert "1.19.5" not in combination
+        assert "1.18.0" in combination

tests/test_utils.py

@@ -56,6 +56,11 @@ def test_canonicalize_version(version, expected):
     assert canonicalize_version(version) == expected
 
 
+@pytest.mark.parametrize(("version"), ["1.4.0", "1.0"])
+def test_canonicalize_version_no_strip_trailing_zero(version):
+    assert canonicalize_version(version, strip_trailing_zero=False) == version
+
+
 @pytest.mark.parametrize(
     ("filename", "name", "version", "build", "tags"),
     [