fix(tags): find current tag matched by a regex-only legacy tag format

Closes #2015

Author: ethanstoner

commitizen/tags.py

@@ -21,7 +21,7 @@
 
 if TYPE_CHECKING:
     import sys
-    from collections.abc import Iterable, Sequence
+    from collections.abc import Iterable, Iterator, Sequence
 
     # Self is Python 3.11+ but backported in typing-extensions
     if sys.version_info < (3, 11):
@@ -232,22 +232,26 @@ def find_tag_for(
         # If the requested version is incomplete (e.g., "1.2"), try to find the latest
         # matching tag that shares the provided prefix.
         if len(release) < 3:
-            matching_versions: list[tuple[VersionProtocol, GitTag]] = []
-            for tag in tags:
-                try:
-                    tag_version = self.extract_version(tag)
-                except InvalidVersion:
-                    continue
-                if tag_version.release[: len(release)] != release:
-                    continue
-                matching_versions.append((tag_version, tag))
+            matching_versions = [
+                (tag_version, tag)
+                for tag_version, tag in self._parse_tag_versions(tags)
+                if tag_version.release[: len(release)] == release
+            ]
 
             if matching_versions:
                 _, latest_tag = max(matching_versions, key=lambda vt: vt[0])
                 return latest_tag
 
         possible_tags = set(self.normalize_tag(version, f) for f in self.tag_formats)
         candidates = [t for t in tags if t.name in possible_tags]
+        if not candidates:
+            # Tag formats with regex-only parts (e.g. `\+.*`) cannot be rendered
+            # by `normalize_tag`, so fall back to comparing extracted versions.
+            candidates = [
+                tag
+                for tag_version, tag in self._parse_tag_versions(tags)
+                if tag_version == version
+            ]
         if len(candidates) > 1:
             warnings.warn(
                 UserWarning(
@@ -279,3 +283,19 @@ def _extract_version(self, match: re.Match[str]) -> str:
         if devrelease := groups.get("devrelease"):
             parts.append(devrelease)
         return "".join(parts)
+
+    def _parse_tag_versions(
+        self, tags: Iterable[GitTag]
+    ) -> Iterator[tuple[VersionProtocol, GitTag]]:
+        """
+        Yield each tag with its extracted version, skipping invalid tags.
+
+        Used when searching tags by version: a tag that matches no tag format,
+        or whose version is rejected by the version scheme, is unrelated to the
+        search and must not abort it.
+        """
+        for tag in tags:
+            try:
+                yield self.extract_version(tag), tag
+            except InvalidVersion:
+                continue

tests/commands/test_bump_command.py

@@ -1345,6 +1345,43 @@ def test_bump_detect_legacy_tags_from_scm(
     assert git.tag_exist("v0.4.3") is True
 
 
+def test_bump_detect_legacy_tag_with_build_metadata_from_scm(
+    tmp_commitizen_project: Path, util: UtilFixture, capsys: pytest.CaptureFixture
+):
+    """Regression test for #2015."""
+    tmp_commitizen_cfg_file = tmp_commitizen_project / "pyproject.toml"
+    tmp_commitizen_cfg_file.write_text(
+        "\n".join(
+            [
+                "[tool.commitizen]",
+                'version_provider = "scm"',
+                'version_scheme = "pep440"',
+                'tag_format = "$version"',
+                "legacy_tag_formats = [",
+                "  '$major.$minor.$patch$prerelease\\+.*'",
+                "]",
+            ]
+        ),
+    )
+    util.create_file_and_commit("feat: initial")
+    util.create_tag("1.0.1rc0+gha")
+    util.create_file_and_commit("fix: bar")
+
+    with pytest.raises(DryRunExit):
+        util.run_cli(
+            "bump",
+            "--yes",
+            "--prerelease",
+            "rc",
+            "--build-metadata",
+            "gha",
+            "--get-next",
+        )
+
+    out, _ = capsys.readouterr()
+    assert out.strip() == "1.0.1rc1+gha"
+
+
 def test_bump_warn_but_dont_fail_on_invalid_tags(
     tmp_commitizen_project: Path,
     util: UtilFixture,

tests/test_tags.py

@@ -101,6 +101,27 @@ def test_find_tag_for_partial_version_ignores_invalid_tags():
     assert found.name == "1.2.1"
 
 
+def test_find_tag_for_full_version_matching_regex_only_legacy_tag_format():
+    """Regression test for #2015: a legacy tag format containing regex-only
+    parts (here ``\\+.*`` for build metadata) cannot be rendered back into a tag
+    name, so the tag must be found by comparing its extracted version.
+    """
+    tags = [
+        _git_tag("not-a-version"),
+        _git_tag("1.2.3foo"),
+        _git_tag("1.0.0"),
+        _git_tag("1.0.1rc0+gha"),
+    ]
+
+    rules = TagRules(legacy_tag_formats=[r"$major.$minor.$patch$prerelease\+.*"])
+
+    found = rules.find_tag_for(tags, "1.0.1rc0")
+
+    assert found is not None
+    assert found.name == "1.0.1rc0+gha"
+    assert rules.find_tag_for(tags, "1.0.2") is None
+
+
 def test_is_version_tag_accepts_semver2_prerelease_in_custom_tag_format():
     """Regression test for #1614: a SemVer2-style prerelease segment such as
     ``rc.0`` (with a literal dot) must be recognised when it appears at the