[diffoscope] Bug#838260: diffoscope: Reduce noise from offsets deltas in readelf(1) diffs

[Jérémy Bobbio]

Chris Lamb:
>> Could these offset differences in readelf(1) output be ignored, at least
>> optionally?
> 
> Love the idea! However, my gut cautions against ignoring them. even with an
> option. 
> 
> Perhaps there is a perfect solution whereby we would normalise these two
> offsets to — making it up here! — relative values, but simply need to 
> nclude that we have done that once in the diff. That way, we have a) still
> captured the underlying issue, b) reduced the noise, and c) avoided a
> cumbersome option flag.

One idea that crossed my mind at some point that might be able to solve
this as well: be able to record other kinds of differences than just
line-oriented ones. Initially, I thought of this as a way to add image
comparison as I felt sad not knowing any free software that could easily
provide similar features to what GitHub offers [1].

But why stop with images? In the precise case of the readelf output,
having line-oriented diff means we are carrying around a useless and
confusing information: the line numbers are not helpful in anyway to
locate and undrstand the differences.

But what if we could replace the line numbers by the instruction
addresses? Then the noise mentioned by Daniel disappears. Meanwhile, the
actual output will become even more relevant.

Such an approach would require some structural changes to the code, but
could have benefits on many fronts.

 [1]: https://help.github.com/articles/rendering-and-diffing-images/

Hope that's any useful,
-- 
Lunar                                .''`.
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