blame -C: adding a line in moved content sometimes affect blame result

blame -C: adding a line in moved content sometimes affect blame result

[Andrew Wong]

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I've attached a script for illustration.

After moving content from file1 to file2, "git blame -C file2" correctly 
shows that the content came from file1. However, if I add a line in near 
the top or bottom of the moved content in file2, "git blame -C file2" 
fails to detect that the top or bottom of the moved contents came from 
file1. I looked around in blame.c, and this feels like a boundary case 
somewhere inside find_copy_in_blob? Any clues?

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Re: blame -C: adding a line in moved content sometimes affect blame result

[Andrew Wong]

On 11-06-08 1:09 AM, Andrew Wong wrote:
> I've attached a script for illustration.
>
> After moving content from file1 to file2, "git blame -C file2" 
> correctly shows that the content came from file1. However, if I add a 
> line in near the top or bottom of the moved content in file2, "git 
> blame -C file2" fails to detect that the top or bottom of the moved 
> contents came from file1. I looked around in blame.c, and this feels 
> like a boundary case somewhere inside find_copy_in_blob? Any clues?
Anyone has any ideas regarding this issue?

Re: blame -C: adding a line in moved content sometimes affect blame result

[Junio C Hamano]

Andrew Wong <andrew.kw.w@gmail.com> writes:
>
> After moving content from file1 to file2, "git blame -C file2"
> correctly shows that the content came from file1. However, if I add a
> line in near the top or bottom of the moved content in file2, "git
> blame -C file2" fails to detect that the top or bottom of the moved
> contents came from file1.

Probably your first few remaining lines of file2 are considered
insignificant copy by the logic in step 4 described in:

    http://thread.gmane.org/gmane.comp.version-control.git/28826

I didn't actually tried to follow what the code does to your exact input,
though.