这是一个非常古老但没有答案的问题。我决定进行调查，发现我可以证明 Git 的行为与问题所说的不同。一种解释是 Git 改进了 bisect 的算法，或者提问者在标记提交时犯了一个错误。
我正在尝试了解更多信息和 git bisect，但在这段历史中遇到了麻烦。我知道这107ca95是好3830e61是坏。当我运行 git bisect 时，提交107ca95..3e667f8被忽略。我碰巧知道这43a07b1是引入回归的提交，但它从未被评估过。
我写了一些代码来检查它是否被评估。我的测试表明它已被评估。运行下面的代码并验证是否Add menu styles.出现了带有消息的提交。
进一步评论：
- “提交
107ca95..3e667f8被忽略”：请注意，您标记为“好”的提交将不会被评估，因为 git 已经知道它是好的。
- 请阅读Christian Couder的这篇文章中的“二分算法”部分。“检查合并基础”部分也可能是相关的。
- 如上所述，问题肯定与我使用的版本不同（问题来自 2013 年，Git 2.11 来自 2016 年）。
平分运行输出
- 请注意，第一个“添加管理员通知”被选中（第 4 行），因为它提供了最多的信息。（阅读上述文章中的“检查合并基础”。）
- 从那时起，它就像预期的那样平分线性历史。
# bad: [d7761d6f146eaca1d886f793ced4315539326866] Add data escaping. (Bad)
# good: [f555d9063a25a20a6ec7c3b0c0504ffe0a997e98] Add Responsive Nav. (Good)
git bisect start 'd7761d6f146eaca1d886f793ced4315539326866' 'f555d9063a25a20a6ec7c3b0c0504ffe0a997e98'
# good: [1b3b7f4952732fec0c68a37d5f313d6f4219e4ae] Add ‘Admin’ notice. (Good)
git bisect good 1b3b7f4952732fec0c68a37d5f313d6f4219e4ae
# bad: [f9a65fe9e6cde4358e5b8ef7569332abfb07675e] Add icons. (Bad)
git bisect bad f9a65fe9e6cde4358e5b8ef7569332abfb07675e
# bad: [165b8a6e5137c40ce8b90911e59d7ec8eec30f46] Add menu styles. (Bad)
git bisect bad 165b8a6e5137c40ce8b90911e59d7ec8eec30f46
# first bad commit: [165b8a6e5137c40ce8b90911e59d7ec8eec30f46] Add menu styles. (Bad)
代码
在Python 3和 Git 2.11.0 中运行。运行命令：python3 script.py
""" The following code creates a git repository in '/tmp/git-repo' and populates
it with the following commit graph. Each commit has a test.sh which can be used
as input to a git-bisect-run.
The code then tries to find the breaking change automatically.
And prints out the git bisect log.
Written in response to http://stackoverflow.com/questions/17267816/git-bisect-with-merged-commits
to test the claim that '107ca95..3e667f8 are never checked out'.
Needs Python 3!
"""
from itertools import chain
import os.path
import os
import sh
repo = {
0x3830e61: {'message': "Add data escaping.", 'parents': [ 0x0f5e148 ], 'test': False} , # Last: (Bad)
0x0f5e148: {'message': "Improve function for getting page template.", 'parents': [ 0xaaf8dc5], 'test': False},
0xaaf8dc5: {'message': "Merge branch 'navigation'", 'parents': [ 0x3e667f8, 0xea3d736], 'test': False},
0x3e667f8: {'message': "Add icons.", 'parents': [ 0x43a07b1], 'test': False},
0x43a07b1: {'message': "Add menu styles.", 'parents': [ 0x107ca95], 'test': False} , # First: (Breaks)
0x107ca95: {'message': "Add Responsive Nav.", 'parents': [ 0xf52cc34], 'test': True}, # First: (Good)
0xea3d736: {'message': "Add ‘Admin’ notice.", 'parents': [ 0x17ca0bb], 'test': True},
0x17ca0bb: {'message': "Update placeholder text.", 'parents': [ 0xf52cc34], 'test': True},
0xf52cc34: {'message': "Add featured image.", 'parents': [ 0x2abd954], 'test': True},
0x2abd954: {'message': "Style placeholders.", 'parents': [], 'test': True},
}
bad = 0x3830e61
good = 0x107ca95
def generate_queue(_dag, parents):
for prev in parents:
yield prev
yield from generate_queue(_dag, _dag[prev]['parents'])
def make_queue(_dag, inits):
""" Converts repo (a DAG) into a queue """
q = list(generate_queue(_dag, inits))
q.reverse()
seen = set()
r = [x for x in q if not (x in seen or seen.add(x))]
return r
if __name__ == '__main__':
pwd = '/tmp/git-repo'
sh.rm('-r', pwd)
sh.mkdir('-p', pwd)
g = sh.git.bake(_cwd=pwd)
g.init()
parents = set(chain.from_iterable((repo[c]['parents'] for c in repo)))
commits = set(repo)
inits = list(commits - parents)
queue = make_queue(repo, inits)
assert len(queue) == len(repo), "queue {} vs repo {}".format(len(queue), len(repo))
commit_ids = {}
# Create commits
for c in queue:
# Set up repo
parents = repo[c]['parents']
if len(parents) > 0:
g.checkout(commit_ids[parents[0]])
if len(parents) > 1:
if len(parents) > 2: raise NotImplementedError('Octopus merges not support yet.')
g.merge('--no-commit', '-s', 'ours', commit_ids[parents[1]]) # just force to use 'ours' strategy.
# Make changes
with open(os.path.join(pwd, 'test.sh'), 'w') as f:
f.write('exit {:d}\n'.format(0 if repo[c]['test'] else 1))
os.chmod(os.path.join(pwd, 'test.sh'), 0o0755)
with open(os.path.join(pwd, 'message'), 'w') as f:
f.write(repo[c]['message'])
g.add('test.sh', 'message')
g.commit('-m', '{msg} ({test})'.format(msg=repo[c]['message'], test='Good' if repo[c]['test'] else 'Bad'))
commit_ids[c] = g('rev-parse', 'HEAD').strip()
# Run git-bisect
g.bisect('start', commit_ids[bad], commit_ids[good])
g.bisect('run', './test.sh')
print(g.bisect('log'))