fix: Treat $version the same as unset tag_format in ScmProvider

This should be non-breaking unless users rely on the looser version
validation of TAG_FORMAT_REGEXS compared to their `version_scheme`.

Author: robertschweizer

commitizen/providers.py

@@ -195,9 +195,9 @@ class ScmProvider(VersionProvider):
 
     def _tag_format_matcher(self) -> Callable[[str], str | None]:
         version_scheme = get_version_scheme(self.config)
-        pattern = (
-            self.config.settings.get("tag_format") or version_scheme.parser.pattern
-        )
+        pattern = self.config.settings.get("tag_format")
+        if pattern in (None, "$version"):
+            pattern = version_scheme.parser.pattern
         for var, tag_pattern in self.TAG_FORMAT_REGEXS.items():
             pattern = pattern.replace(var, tag_pattern)
 

docs/bump.md

@@ -326,7 +326,7 @@ These are used in:
   * If `--incremental`: Using latest version found in the changelog, scan existing Git tags with 89\% similarity match. 
   * `--rev-range` is converted to Git tag names with `tag_format` before searching Git history.
 * If the `scm` `version_provider` is used, it uses different regexes to find the previous version tags:
-  * If no `tag_format` is set: `VersionProtocol.parser` (allows `v` prefix)
+  * If `tag_format` is unset or set to `$version`: `VersionProtocol.parser` (allows `v` prefix)
   * If `tag_format` is set: Custom regex similar to SemVer (not as lenient as PEP440 e.g. on dev-releases)
 
 Commitizen supports 2 types of formats, a simple and a more complex.

tests/test_version_providers.py

@@ -175,17 +175,17 @@ def test_file_providers(
 @pytest.mark.parametrize(
     "tag_format,tag,expected_version",
     (
-        # If tag_format is None, version_scheme.parser is used.
+        # If tag_format is None or $version, version_scheme.parser is used.
         # Its DEFAULT_VERSION_PARSER allows a v prefix, but matches PEP440 otherwise.
         (None, "0.1.0", "0.1.0"),
         (None, "v0.1.0", "0.1.0"),
         (None, "no-match-because-version-scheme-is-strict", "0.0.0"),
-        # If tag_format is not None, TAG_FORMAT_REGEXS are used, which are much more
-        # lenient.
-        ("$version", "match-TAG_FORMAT_REGEXS", "match-TAG_FORMAT_REGEXS"),
+        ("$version", "no-match-because-version-scheme-is-strict", "0.0.0"),
         ("$version", "0.1.0", "0.1.0"),
         ("$version", "v0.1.0", "0.1.0"),
-        ("$version", "v-0.1.0", "0.1.0"),
+        ("$version", "v-0.1.0", "0.0.0"),
+        # If tag_format is not None or $version, TAG_FORMAT_REGEXS are used, which are
+        # much more lenient but require a v prefix.
         ("v$version", "v0.1.0", "0.1.0"),
         ("v$version", "no-match-because-no-v-prefix", "0.0.0"),
         ("v$version", "v-match-TAG_FORMAT_REGEXS", "-match-TAG_FORMAT_REGEXS"),