Git - How do I manage built files in different branches?

Question

Some Background

I have been using Git for a while now. The projects that I have been working on have not been too complicated in regards to branches/tags.

I have decided to use git-svn at work. The SVN repository has many different branches. A lot of these branches are customer customized versions of the trunk.

The Problem

I often work on problems for different customers at different the same time. So I switch back and forth between branches all the time. The problem is that to test the products I have to rebuild the project each time I switch between branches. A build takes > 2 hours (from scratch):(

I am assuming that there is a way to stash the build files in branch customer_a and then checkout customer_b, modify, build, test, commit. Then stash the build files and checkout customer_a again and pop the customer_a stash to get back to where I was.

This only works if the build files are tracked (i.e. added or committed). I do not want to track the build files and I definitely do not want to check them in. Is there a way to stash (or do something similar) for non-tracked files? Or a common practice that people use to achieve the same type of thing?

Note that the way our project gets built each library (of which there are thousands) gets builds the files local to the library folder i.e. they are not moved to a build folder at the root of the project. All the built files are spread out all over the place.

Update...

So based on some of the comments I think I need to give an example of my problem

Here is my folder structure.

branch1/
      src/
         component1/
                    c1.c
         component2/
                    c2.c
      libsrc/
          library1/
                    lib_1.c
          library2/
                    lib_2.c

branch2/
      src/
         component1/
                    c1.c
         component2/
                    c2.c
      libsrc/
          library1/
                    lib_1.c
          library2/
                    lib_2.c

So the problem is that branch1 and branch2 have the same ancestry but have diverged quite a bit. So if I check out branch1 and build it I will get binaries (e.g. lib_1.o) that I link against in my Makefile to build the final component binaries.

If I then checkout branch2 make a change to c1.c and run make it tries to link to the binaries that were created by branch1 (lib_1.o), since they still exist in the directories as built in the previous branch. To avoid this I have to do a clean build each time I switch branches (which takes hours).

Answer 1

Perhaps I'm missing something obvious, but when switching branches, Git won't touch untracked or ignored files, so if you build a product in one branch and then switch to another branch, the built products should remain.

Answer 2

The problem is that you need to get back the right binaries:

• not only need for the right branch,
• but also for the right version

The last point is not overly important if you keep developing the latest versions of your 2 branches (and accept to rebuilt everything if you checkout an old tag and branch from there).
But still, if after a build you automatically publish those '.o' files into a repository made for managing binaries, that would solve your problem neatly.
A local Nexus repo for instance would be appropriate.

Answer 3

Okay

So this question has been unanswered for a while now and I just been trying different solutions locally.

The best one I came up with is to use pre amd post checkoout hooks.

Here is what I have done

1. Create a .binaries folder at the top level of your repository and add it to the .gitignore file.

2. Add the file formats of the binaries to your .gitignore file also.

3. write a script in your favorite scripting language to find all files of said format that moves them to the .binaries/<BRANCH>/ folder under the same path structure e.g. src/library1/lib1.o should be MOVED to .binaries/<BRANCH>/src/library1/lib1.o - this should be called by pre-checkout

4. Write a script to move files from the .binaries folder into the current branch e.g. .binaries/<BRANCH>/src/library1/lib1.o should be MOVED to src/library1/lib1.o - this should be called by post-checkout

Now switching between branches will revert to the binaries that were built during for that branch only and you will have a clean checkout when creating a new branch.