How to create a repo whose code are used by two other projects?

[jianbai-wang]

I currently have two separate repositories, say A and B for building two products. There are a large number of common code exist in both repositories. I want to create a repo C to host those common code and remove them from both A and B. My question is: how to clone, checkout, commit either one of the product code together with the common code, i.e., (A, C) or (B, C) consistently? Can it be done in SourceTree? 

[Mikael Sandberg]

There are two options, three is you want to use git submodules which I do not recommend. You can either use Git subtrees to do it, or repo which is a tool from Google. Git subtrees works best for Bitbucket/Sourcetree. You can find out more about Git subtrees in this article, Alternatives To Git Submodule: Git Subtree