Find the merge commit that modified a given line?

Question

We're using a git-flow style workflow, and we want to find out which pull request included changes to a given line of code.

Suppose we have the following history:

       c---e---g
      /         \
-a---b---d---f---h--- master

My pull request was merged in h with commit message "Merge pull request #123".

If I do a git blame on the lines of code added in the pull request, it shows me e, rather than h.

12345678 (Wilfred Hughes           2015-02-02 15:22:40 +0000 402) # Some old code
e        (Wilfred Hughes           2015-02-12 15:22:40 +0000 402) # Added in the PR, line 1
e        (Wilfred Hughes           2015-02-12 15:22:40 +0000 403) # Added in the PR, line 2
56789012 (Wilfred Hughes           2015-02-26 17:24:18 +0000 404) # More old code

How can I find the merge commit for a given line of code in git?

(Note this is different from this related question as I'm starting with lines of code, not commits).

Answer 1

A merge-commit would only appear in git-blame if you had resolved conflict in that commit.

For normal merges without conflict, h would never appear in git blame as it did not change in any line of code and merely merged g and f.

So what you want can be achieved in 2 phases

1. First find which commit impacted line of code you are interested in. This can be achieved via git blame -L option ( comes in git 1.8.4). Give a range of 10+ lines as it is likely exact line number might have changed.

   $ git blame -L200,+10 -- filename.ext

2. Find the first merge commit following the commit found in step 1 So you would have to first find which commit impacted the line of code you are interested in. This can be achieved as answered in Find merge commit which include a specific commit