Blaming diffs

Hi,

It seems to me there is no tool to "blame diffs", i.e. something to know
what commit(s) is(are) responsible for a set of changes.

For example, the following script tries to get the set of commits
involved in the changes between $A and $B. Note it only works for text
additions. 

git diff --unified=0 $A $B | awk 'BEGIN { FS="(^(--- a/|+++ b/)|^@@ -[0-9,]+ \\+| @@)" } /^---/ || ( /^+++ b\/(.*)/ && file=="" ) { file = $2 } /^@@/ {split($2, a, /,/); a[2] = a[2] ? a[2] + a[1] - 1 : a[1]; print "git blame -l -L " a[1] "," a[2], "'$A..$B'", file }' | sh | cut -f 1 -d " " | sort -u

Has anyone tried to work on something similar yet ?

If not, as git users, what kind of output would you expect from such a
tool, and where do you think this should lie (extension to git diff, or
separate tool) ?

Cheers,

Mike

On Sun, Sep 16, 2007 at 07:05:35PM +0200, Frank Lichtenheld [off-list ref] wrote:

On Sun, Sep 16, 2007 at 06:38:29PM +0200, Mike Hommey wrote:

quoted

It seems to me there is no tool to "blame diffs", i.e. something to know
what commit(s) is(are) responsible for a set of changes.

For example, the following script tries to get the set of commits
involved in the changes between $A and $B. Note it only works for text
additions. 

git diff --unified=0 $A $B | awk 'BEGIN { FS="(^(--- a/|+++ b/)|^@@ -[0-9,]+ \\+| @@)" } /^---/ || ( /^+++ b\/(.*)/ && file=="" ) { file = $2 } /^@@/ {split($2, a, /,/); a[2] = a[2] ? a[2] + a[1] - 1 : a[1]; print "git blame -l -L " a[1] "," a[2], "'$A..$B'", file }' | sh | cut -f 1 -d " " | sort -u

Has anyone tried to work on something similar yet ?

If not, as git users, what kind of output would you expect from such a
tool, and where do you think this should lie (extension to git diff, or
separate tool) ?

What do you use for $A and $B? commits? What is the difference between
your script and "git log --pretty=format:%H $A..$B"
then?

In my typical usecase, $A is upstream and $B is HEAD. What happens is
that my work branch includes some changes that have been merged upstream
and some others that are not yet, or won't because it's not appropriate.
I obviously occasionally merge the upstream branch back, in which case
my changes that were committed upstream don't appear in a git diff $A $B
anymore.

git log --pretty=format:%H $A..$B would give me the list of all commits
that occurred on my branch, while my script only gives the commits
containing changes that are still not applied upstream.

Mike

On Sun, Sep 16, 2007 at 06:38:29PM +0200, Mike Hommey wrote:

It seems to me there is no tool to "blame diffs", i.e. something to know
what commit(s) is(are) responsible for a set of changes.

For example, the following script tries to get the set of commits
involved in the changes between $A and $B. Note it only works for text
additions. 

git diff --unified=0 $A $B | awk 'BEGIN { FS="(^(--- a/|+++ b/)|^@@ -[0-9,]+ \\+| @@)" } /^---/ || ( /^+++ b\/(.*)/ && file=="" ) { file = $2 } /^@@/ {split($2, a, /,/); a[2] = a[2] ? a[2] + a[1] - 1 : a[1]; print "git blame -l -L " a[1] "," a[2], "'$A..$B'", file }' | sh | cut -f 1 -d " " | sort -u

Has anyone tried to work on something similar yet ?

If not, as git users, what kind of output would you expect from such a
tool, and where do you think this should lie (extension to git diff, or
separate tool) ?

What do you use for $A and $B? commits? What is the difference between
your script and "git log --pretty=format:%H $A..$B"
then?

Gruesse,
-- 
Frank Lichtenheld [off-list ref]
www: http://www.djpig.de/

Le dimanche 16 septembre 2007, Mike Hommey a écrit :

Hi,

It seems to me there is no tool to "blame diffs", i.e. something to know
what commit(s) is(are) responsible for a set of changes.

I don't know if that's what you are looking for but perhaps you could 
use "git bisect run". You just need to pass it a script that returns 1 when 
it finds the changes and 0 otherwise. (See git-bisect man page.)

Sometimes ago I sent a patch that would allow "!" after "git bisect run", 
but it seems to have been forgotten. This patch makes it possible to use:

git bisect run ! grep some_stuff file1 file2...

This would give you the commit where some_stuff was introduced in file1 or 
file2...

Regards,
Christian.

Christian Couder [off-list ref] wrote:

Le dimanche 16 septembre 2007, Mike Hommey a écrit :

quoted

It seems to me there is no tool to "blame diffs", i.e. something to know
what commit(s) is(are) responsible for a set of changes.

I don't know if that's what you are looking for but perhaps you could 
use "git bisect run". You just need to pass it a script that returns 1 when 
it finds the changes and 0 otherwise. (See git-bisect man page.)

That's very inefficient to search for something...
 

Sometimes ago I sent a patch that would allow "!" after "git bisect run", 
but it seems to have been forgotten. This patch makes it possible to use:

git bisect run ! grep some_stuff file1 file2...

This would give you the commit where some_stuff was introduced in file1 or 
file2...

Is `git log -Ssome_stuff -- file1 file2` somehow not working for you?

-- 
Shawn.

Le lundi 17 septembre 2007, Shawn O. Pearce a écrit :

Christian Couder [off-list ref] wrote:

quoted

I don't know if that's what you are looking for but perhaps you could
use "git bisect run". You just need to pass it a script that returns 1
when it finds the changes and 0 otherwise. (See git-bisect man page.)

That's very inefficient to search for something...

Perhaps but you can search using whatever script or command you want/know. 
You are not limited by those implemented in git.

You can also make it more efficient with "git bisect {start,good,bad}".

Regards,
Christian.