Find who & when deleted a line in a function using GIT

Question

I have some ruby code in a huge repo like this

def my_func params
  {
    :k1 => 1,
    :k2 => 2,
    :k3 => 3,
    :k4 => 4,
    :k5 => 5,
    :k6 => 6
  }
end

Somehow, few key-value pairs got deleted over time. I want to git blame who did this, But the key-value pair is so common that a grep would cause too many false-positives. So is there a way to view a function's change over all commits?

I tried something like git log -L /^\s+def my_func/,/^\s+def/ src/to/file.rb, didn't work. GUI tools like SourceTree has "Log this file", it only shows the diff, so I can not tell which function the change belongs to. I also searched stackoverflow and googled a bit, didn't find a universal way.

Are you saying those lines are present so many times and deleted so many times you can't search via the -G option to log or with pickaxe? — Andrew C, Oct 15 '14 at 01:30
@AndrewC yes, and what's worse, I don't really remember what exactly need to be deleted, the first version has lots of k-v pairs, the current version has too few. I need to work out why some got deleted by design or by mistake. — λq_, Oct 15 '14 at 06:23

score 1 · Accepted Answer · answered Oct 15 '14 at 01:31

In that case you can perform a "reverse blame". You simply ask the "difference" from the "new" to the old file, so deletions become addtions and vice versa.

git blame --reverse start..end file.ext

Where start and end should be commit signatures.

For each line, it will show the latest commit in which the line appeared. You can then derive the next commit to find out what happened.

Find who & when deleted a line in a function using GIT

1 Answers1