[Fix] Fix setuptools-scm version resolution for rc tags (#22165)

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Co-authored-by: Baizhou Zhang <sobereddiezhang@gmail.com>

python/tools/get_version_tag.py

@@ -0,0 +1,171 @@
+#!/usr/bin/env python3
+"""Resolve the correct version tag for setuptools-scm.
+
+Called by setuptools-scm via git_describe_command in pyproject.toml.
+Outputs either a bare tag (e.g., "v0.5.10") for exact-match commits,
+or a `git describe --long` string (e.g., "v0.5.10-2-gabcdef0") for
+untagged commits. Both formats are accepted by setuptools-scm.
+
+This two-step approach avoids a strverscmp bug where
+`git tag --sort=-version:refname` sorts v0.5.10rc0 above v0.5.10,
+which would cause CI to build the wrong version.
+
+Strategy:
+1. If the current commit has an exact version tag, use it directly.
+   This handles CI release builds (both stable and rc).
+2. Otherwise, find the highest version tag across all branches
+   and describe relative to it. This handles local dev installs
+   from main where release tags only exist on release branches.
+"""
+
+import re
+import subprocess
+import sys
+
+
+def parse_version_tuple(tag: str) -> tuple:
+    """Parse a version tag into a sortable tuple using PEP 440 ordering.
+
+    Returns a tuple where:
+    - Base version parts are integers: (major, minor, patch)
+    - Pre-release suffix gets a lower sort key than bare version:
+      v0.5.10rc0  -> (0, 5, 10, 0, 0)   # pre-release
+      v0.5.10     -> (0, 5, 10, 1, 0)   # stable (sorts higher)
+      v0.5.10post1 -> (0, 5, 10, 2, 1)  # post-release (sorts highest)
+    """
+    v = tag.lstrip("v")
+    # Split base version from suffix
+    m = re.match(r"^(\d+)\.(\d+)\.(\d+)(?:(rc|post)(\d+))?$", v)
+    if not m:
+        return (0, 0, 0, 0, 0)
+    major, minor, patch = int(m.group(1)), int(m.group(2)), int(m.group(3))
+    suffix_type = m.group(4)
+    suffix_num = int(m.group(5)) if m.group(5) else 0
+    if suffix_type == "rc":
+        return (major, minor, patch, 0, suffix_num)
+    elif suffix_type == "post":
+        return (major, minor, patch, 2, suffix_num)
+    else:
+        return (major, minor, patch, 1, 0)
+
+
+def run_git(*args: str, allow_failure: bool = False) -> str:
+    """Run a git command and return stripped stdout.
+
+    Args:
+        allow_failure: If True, return "" on non-zero exit (expected for
+            commands like --exact-match that legitimately fail).
+            If False, log stderr on failure before returning "".
+    """
+    try:
+        result = subprocess.run(
+            ["git", *args],
+            capture_output=True,
+            text=True,
+        )
+    except OSError as exc:
+        print(f"ERROR: Failed to run 'git {' '.join(args)}': {exc}", file=sys.stderr)
+        sys.exit(1)
+
+    if result.returncode != 0:
+        if not allow_failure:
+            stderr_msg = result.stderr.strip()
+            print(
+                f"WARNING: git {' '.join(args)} failed "
+                f"(exit {result.returncode}): {stderr_msg}",
+                file=sys.stderr,
+            )
+        return ""
+
+    return result.stdout.strip()
+
+
+def get_exact_version_tag() -> str:
+    """Return the version tag name if HEAD has an exact version tag, or empty string."""
+    return run_git(
+        "describe", "--tags", "--exact-match", "--match", "v*", allow_failure=True
+    )
+
+
+def get_latest_version_tag_describe() -> str:
+    """Find the highest version tag and build a describe string relative to it.
+
+    Uses PEP 440 version ordering so that stable releases sort above
+    pre-release tags (e.g., v0.5.10 > v0.5.10rc0).
+
+    The highest tag may live on a release branch and not be a direct
+    ancestor of HEAD (e.g., main diverged before the release tag was
+    created). In that case, we compute the commit distance from the
+    merge-base and build the describe string manually.
+    """
+    tag = get_latest_version_tag()
+    if not tag:
+        print("WARNING: No version tags (v*.*.*) found in repo", file=sys.stderr)
+        return ""
+
+    # Fast path: tag is an ancestor of HEAD, git describe works directly
+    result = run_git(
+        "describe", "--tags", "--long", "--match", tag, "HEAD", allow_failure=True
+    )
+    if result:
+        return result
+
+    # Tag is not an ancestor (e.g., release branch diverged from main).
+    # Build describe string manually: {tag}-{distance}-g{hash}
+    merge_base = run_git("merge-base", tag, "HEAD", allow_failure=True)
+    if not merge_base:
+        print(
+            f"WARNING: No common ancestor between {tag} and HEAD. "
+            f"Is this a shallow clone? Try: git fetch --unshallow --tags",
+            file=sys.stderr,
+        )
+        return ""
+    distance = run_git("rev-list", "--count", f"{merge_base}..HEAD")
+    short_hash = run_git("rev-parse", "--short", "HEAD")
+    return f"{tag}-{distance}-g{short_hash}"
+
+
+def get_version_describe() -> str:
+    """Main entry point: resolve the version describe string."""
+    # Prefer exact match — correct for both stable and pre-release tags
+    exact = get_exact_version_tag()
+    if exact:
+        return exact
+
+    # Fallback for untagged commits (e.g., dev install from main)
+    return get_latest_version_tag_describe()
+
+
+def get_latest_version_tag() -> str:
+    """Return just the highest version tag (PEP 440 ordered), or empty string."""
+    tags_raw = run_git("tag", "--list", "v*.*.*")
+    if not tags_raw:
+        return ""
+    tag_list = sorted(tags_raw.splitlines(), key=parse_version_tuple, reverse=True)
+    return tag_list[0] if tag_list else ""
+
+
+def main() -> None:
+    # --tag-only: print just the latest version tag (for CI scripts)
+    tag_only = "--tag-only" in sys.argv
+    if tag_only:
+        result = get_latest_version_tag()
+    else:
+        result = get_version_describe()
+    if not result:
+        print(
+            "ERROR: Could not determine version from git tags.\n"
+            "Possible causes:\n"
+            "  - No version tags (v*.*.*) exist: run 'git fetch --tags'\n"
+            "  - Shallow clone without tags: run 'git fetch --unshallow --tags'\n"
+            "  - Git safe.directory issue: run 'git config --global --add safe.directory <repo>'\n"
+            "  - Not inside a git repository\n"
+            "setuptools-scm will fall back to version 0.0.0.dev0",
+            file=sys.stderr,
+        )
+        sys.exit(1)
+    print(result)
+
+
+if __name__ == "__main__":
+    main()