英文:
Why is git-log with perl regex negative lookbehind causing a fatal error?
问题
I cannot get git-log's regexp grep functionality to search using perl based regexp (pcre) or I can but it is not working with negative lookbehind.
git log -p -P -G'(?<!-)title'
results in output
fatal: invalid regex: Invalid preceding regular expression
However, pcre support and negative lookbehind seems to be working, if git-grep is any indicator.
E.g. git grep -P '(?<!-)title' returns expected results.
git version 2.21.0 (Apple Git-122.2)
英文:
Either I cannot get git-log's regexp grep functionality to search using perl based regexp (pcre) or I can but it is not working with negative lookbehind.
git log -p -P -G'(?<!-)title'
results in output
fatal: invalid regex: Invalid preceding regular expression
However, pcre support and negative lookbehind seems to be working, if git-grep is any indicator.
E.g. git grep -P '(?<!-)title' returns expected results.
git version 2.21.0 (Apple Git-122.2)
答案1
得分: 2
"-P" 不影响 "-G"。您可以通过将 "-P" 替换为 "-F"（或 --fixed-string）来验证这一点：即使在固定字符串中没有任何查找，您仍将收到相同的错误。
"-P" 的文档中提到
将限制模式视为 Perl 兼容的正则表达式。
注意这里的 "模式" 一词。确实，--grep 选项也提到了它：
--grep=
另一方面，"-G" 没有提到：
-G
英文:
The -P doesn't influence -G. You can verify it by replacing -P with -F (or --fixed-string): you'll still get the same error, even if there's no look-around at all in fixed strings.
The documentation of -P says
> Consider the limiting patterns to be Perl-compatible regular expressions.
Note the word "patterns". Indeed, the --grep options mentions it:
> --grep=<pattern>
On the other hand, -G doesn't:
> -G<regex>
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