Common makefile (gasp) stuff

[Andrei Alexandrescu via Digitalmars-d]

On 1/13/15 7:44 PM, Daniel Murphy wrote:
> "Andrei Alexandrescu"  wrote in message
> news:m9497d$1pv2$1 at digitalmars.com...
>
>> Over the time a number of stuff has become quite duplicated across our
>> makefiles for dmd, druntime, and phobos.
>>
>> These include fetching OS and model but (newer) general-purpose macros
>> for e.g. rebasing repos, see
>> https://github.com/D-Programming-Language/dlang.org/blob/master/posix.mak#L37.
>>
>>
>> I think it's time to reduce clutter and duplication by migrating such
>> common stuff into one common.mak file. Question is, where should that
>> file sit? One candidate is tools/ but it's not really a tool. Another
>> candidate is dmd/src/ because that would be the first thing anyone
>> depends on.
>>
>> Ideas?
>
> If it's optional extra stuff like git shortcuts, then removing it from
> the makefiles and putting it in tools makes sense.  If it's mandatory
> stuff like OS detection, then it needs to stay where it is.

Hmmm... I wonder why the distinction.

> What's the actual problem you're trying to solve with this?  IMO
> duplication is less of a problem than overcomplicating the makefiles.

The problem is basic code duplication with its known liabilities. I'm 
looking at stuff like this:

https://github.com/D-Programming-Language/dlang.org/blob/master/posix.mak#L58

https://github.com/D-Programming-Language/phobos/blob/master/posix.mak#L31

https://github.com/D-Programming-Language/druntime/blob/master/posix.mak#L8

Three's a charm. That code is relatively verbose (required newlines). I 
trust it doesn't need updates often, but it occupies real estate in a 
readily accessible position (beginning of file).

The real issue here is that acquiescing to such duplication discourages 
attempts at uniformization before they occur. I'm thinking of simpler, 
clearer naming conventions and uniform ways of doing the same things 
(such as unittesting or documentation).

Getting back to REBASE 
(https://github.com/D-Programming-Language/dlang.org/blob/master/posix.mak#L37), 
it greatly simplifies my building the entire website in a way I trust is 
nice:

   make rebase -j && make clean && make rsync -j

(Sadly make clean is necessary because of dub, which makes the process 
take a lot longer than it should; with luck, somebody will improve on 
that soon.)

Now "make rebase" is really useful for druntime and phobos as well. But 
between duplicating more code or just doing it by hand, one may as well 
give up and choose the latter.

I'd also like to define "make rebase-dirty" based on this:

REBASE_DIRTY = MYBRANCH=`git rev-parse --abbrev-ref HEAD` &&\
  git stash &&\
  git co master &&\
  git pull --ff-only upstream master &&\
  git co $$MYBRANCH &&\
  git rebase master &&\
  git stash pop

which is useful because it lets me rebase on top of work in progress. 
Again the prospect of duplicating this other macro across 3-4 projects 
is fairly unattractive.



Andrei