Re: [PATCH] t4202 (log): add failing test for log with subtree

From: Matthieu Moy <matthieu.moy@grenoble-inp.fr>
Date: Apr 22, 2013, 18:18 UTC
Message-ID: <vpqzjwqzawf.fsf@grenoble-inp.fr>
In-Reply-To: <CALkWK0madWxOSraZw6u8U_afVeK8tyMB_+D59n1vSBmobxGqqg@mail.gmail.com>

Ramkumar Ramachandra <artagnon@gmail.com> writes:

> Meanwhile, you're evading the issue of assuming that all trees are
> read into /, and are really representing the same project's history,
> while this is not the case.

This is fundamenally how Git works. Git works with commit objects, each commit object points to a tree object that represent "/" at this commit.

When you do a subtree merge, you include the tree that was in "/" in a subtree of the master project. Files used to exist as /file, and now exist as /subtree/file. There is nothing recording that the new /subtree/file comes from /file in its second parent. Call this a renaming or not, but "git log subtree/file" won't show you changes touching "/file" by default, and this is the case for the history of the subproject you are merging.

A subtree merge is really a rename of the subproject's file plus a merge, done in the same commit. Try doing something like

mkdir -p subproject git mv * subproject/ git commit

in your subproject before doing a merge, you'll get the same result, except there will be one more commit.

-- 
Matthieu Moy
http://www-verimag.imag.fr/~moy/