Common makefile (gasp) stuff

[Andrei Alexandrescu via Digitalmars-d]

On 1/14/15 12:18 PM, H. S. Teoh via Digitalmars-d wrote:
> If you set up a
> "super-repo", it would look something like this:
>
> 	dlang/			# root git repo
> 		dmd/		# git submodule referencing the dmd repo
> 		druntime/	# git submodule referencing the druntime repo
> 		phobos/ 	# git submodule referencing the phobos repo
> 		dlang.org/	# git submodule referencing the dlang.org repo
>
> Then checking out this new dlang repo (with the requisite git flags)
> will create the above structure for you, including clone all the
> sub-repos. *This* is what will address point (2) that I raised earlier:
> the user shouldn't need to manually setup some arbitrary directory
> structure for you -- automate this with git submodules instead!

Agreed. Ah, this is getting interesting, thanks. So I've wanting to look 
into submodules for a while now but have been discouraged by the bad 
press they seem to be getting:

https://codingkilledthecat.wordpress.com/2012/04/28/why-your-company-shouldnt-use-git-submodules/

http://ayende.com/blog/4746/the-problem-with-git-submodules

http://blogs.atlassian.com/2013/03/git-submodules-workflows-tips/

http://blogs.atlassian.com/2013/05/alternatives-to-git-submodule-git-subtree/

http://somethingsinistral.net/blog/git-submodules-are-probably-not-the-answer/ 
(though I have no idea whether what's relevant for puppet is relevant to us)

> Having such a super-repo will also solve the problem of git bisecting
> earlier toolchain releases -- because the super-repo references the
> sub-repos by SHA hashes, which are history-tracked by git, so we could
> set it up so that each commit of the super-repo corresponds with a valid
> version set of dmd/druntime/phobos. Then you could checkout a specific
> commit of the super-repo and update git submodules, and you'll get a
> snapshot of the entire toolchain as it stood at the time of the commit.
> If we do this right, we could even have the autotester update the
> super-repo automatically upon successful completion of the test suite
> for the entire toolchain.
>
> And ideally, stuff common to multiple subrepos should be in this
> "super-repo", such as the stuff you're trying to factor out right now.
> Including the master makefile that will build everything WITHOUT needing
> to reference out-of-tree paths. And ideally, any out-of-tree references
> needed by the subrepos will be via configurable parameters (e.g. $(DMD),
> $(DRUNTIME_PATH), etc.), which the master makefile can set to the
> correct values, so the subrepos don't have to know or hardcode where the
> exact out-of-tree location ought to be.
>
> Such a super-repo will also make release management easier: instead of
> manually managing release tags in each of dmd/druntime/phobos, we can
> tag the super-repo, which encapsulates the exact set of
> dmd/druntime/phobos commits for that release.

I hear you but The Internet says submodules are a kind of a bummer.


Andrei