[LLVMdev] [cfe-dev] RFC: Upcoming Build System Changes

[Óscar Fuentes]

Daniel Dunbar <daniel at zuster.org> writes:

>> Dan proposes to have a file with the info and processing that file for
>> generating stuff for cmake and `make' (after making the necessary
>> changes on both builds.) What I propose is to read that info from cmake
>> itself. No python required. How is that blocking future improvements?
>
> FWIW, I'm fine with reading that information from CMake, but I imagine
> that over time as more stuff moves into shared files the burden of
> implementing the CMake logic to deal with that data is just not worth
> it (as opposed to leveraging a shared tool).

So let's the imagination fly and ask what could realistically end on the
shared files: list of source files, library dependencies, per-project
settings (rtti, exceptions, etc) what else?

By your plan, adding support for each part will require, at least, to
modify the Python scripts for emitting the cmake declarations, and
sometimes modifiyng the cmake build for handling those
declarations. Daniel, I'm pretty sure that directly reading the shared
files will require simpler modifications to the cmake build. Bear in
mind that if those shared files end containing something sophisticated
(i.e. hard to parse) almost certainly adding support for that on the
cmake/make part will be complex as well.

Another question is user options. Currently the configure script
supports certain features, cmake others. Each own has its standard
syntax and a set of universal settings which are familiar for the users
of each system. Would your system add a new interface of user settings
that everybody will have to learn?