Find Git merge conflicts

find_merge_conflicts.py

# https://stackoverflow.com/questions/55817243/does-git-keep-a-record-of-past-merge-conflicts
import subprocess
import sys

def list_merges():
    proc = subprocess.run(
        ['git', 'rev-list', '--parents', '--min-parents=2', '--all'],
        stdout=subprocess.PIPE,
        check=True,
        encoding='ASCII',
    )
    merges = []
    for line in proc.stdout.splitlines():
        fields = line.split()
        merges.append((fields[0], fields[1:]))
    print('Found {} merges'.format(len(merges)), file=sys.stderr)
    return merges

def analyze_merge(commit, parents):
    subprocess.run(
        ['git', 'checkout', '--quiet', '--detach', parents[0]],
        check=True,
    )
    out = subprocess.run(
        ['git', 'merge', '--quiet', '--no-commit', '--no-ff', *parents[1:]],
        stdout=subprocess.DEVNULL,
    )
    if out.returncode:
        # Merge conflicts
        print("Merge conflict: commit={}".format(commit))
        out = subprocess.run(
            ['git', 'status', '--porcelain'],
            stdout=subprocess.PIPE,
            check=True,
            encoding='ASCII',
        )
        for line in out.stdout.splitlines():
            if line.startswith("UU"):
                print("    File: {}".format(line[3:]))
    subprocess.run(
        ['git', 'merge', '--abort'],
        check=True
    )

def main():
    for commit, parents in list_merges():
        analyze_merge(commit, parents)

if __name__ == "__main__":
    main()