[parted-devel] nuke trailing blanks *without* inducing conflicts

Jim Meyering jim at meyering.net
Tue Feb 24 13:22:21 UTC 2009

FYI, the condition of Parted's sources has been a thorn
in our side for too long, and I've just realized that at
least part of that can be resolved easily: by removing all
trailing blanks (let's call them TB, like the disease).

Of course, when you say "global changes", everyone with a grain of
version-control experience says "don't do that, it'll induce needless
conflicts".  And they're right -- at first glance.  However, if you
have an existing change, patch, branch etc. against the old TB-afflicted
sources, you can easily adjust it to apply to the new, TB-cleaned
sources.  Just filter it through this:

  perl -pe 's/[ \t]+$//'

then it will apply just as well to the post-cleanup as the
original applied to the pre-cleanup code.

I've just confirmed that this can be done by demonstrating on
the 45-change-set "next" branch.

First I recorded all of the changes on next:

    git co next
    git fp --stdout master > next.diff

Then in my working tree, I made the following change and committed
the result [note that's a space and a tab in the first pair of brackets]:

    git grep -l '[ 	]$'|xargs perl -pi -e 's/[ \t]+$//'

that left me with a (not yet pushed) commit modifying lots of files:

     107 files changed, 1463 insertions(+), 1463 deletions(-)

Then I created a branch off that new commit:

    git co -b next-no-trailing-blanks

performed the same transformation on the saved patch:

    perl -pi -e 's/[ \t]+$//' next.diff

and applied it:

    git am next.diff

No conflicts.  and no more trailing blanks.

So, unless someone can come up with a convincing argument
for *not* making this change, I'll make it soon, rebase "next"
as outlined above, and enable the "make syntax-check" that will
spot any violation of the new policy.

P.S. Resolving the indent-with-TAB vs indent-with-spaces
problem may well be nearly as easy.  For another day...

Note: things like normalizing indentation levels, brace positioning,
and general formatting styles are still not even on the radar.

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