Minor build script enhancements

[AndreyPavlenko]

• Added -s option for the build dir suffix.
• Added -v option that allows to build LLVM only.
• Get the IMEX repository url directly from the cmake file.
• Changed the IMEX source directory to imex-src - this directory is also used by cmake.

[dchigarev]

@leshikus are you okay with the changes?

[leshikus]

Sorry, forgot to finalize

[leshikus]

there is better, more transparent and standard way to use this; while [ -v 1 ]; do ; -v is bash specific, one may use -n $1 instead

[AndreyPavlenko]

But you have to use shift in each case statement. How is it better? For single value arguments (that we had before) for arg in "$@" seems much less verbose.

[leshikus]

I believe adding dir suffixes is overengineering as well as the previous attempt to make LLVM location configurable; the common approach is the following: each build environment has exactly the same directories; if you need another environment, you just clone the existing as a whole, this can be done via docker or rsync command; this makes scripts less confusing

[AndreyPavlenko]

With suffixes I can have different builds (debug, release, with imex, without imex) without changing my dev environment. In this way, I can test my changes in different configurations. When creating clones, I also need to populate my changes to each clone, having IDE configurations for each clone, etc.

[leshikus]

I guessed the intention correctly. My point is the compile script is incorrect tool to implement that logic. You've already have a number of existing tools like docker. We can think together about separate clone_env script, it may use docker or rsync or and git checkout of some dev branch.

Why each environment should look as another? This follows standard linux approach "clone the project to directory and run make test". People expect this, and they never learn your suffixes.

[AndreyPavlenko]

Suffixes are optional, people are not required to use them. A simple use-case - I've made some changes (not yet committed) in my IDE and want to test with and without IMEX. For this I need not only to build the project with different options, but also to build 2 different versions of LLVM. I just launch the build script from my build env with different suffixes.

[leshikus]

Is it possible to have these changes as a part of a separate script?

[AndreyPavlenko]

This is definitely possible, the main question - why do we need one more script?

[leshikus]

everyone uses compile.sh; how many users of compile.sh will be using these suffixes? likely only you; that's separate things we put into compile.sh from the ones we put into some other script

[AndreyPavlenko]

But creating a separate script just for me does not make sense either.