[webkit-dev] New build system for gdk/linux

[Krzysztof Kowalczyk]

This e-mail is to let interested people know about my new build system
for gdk/linux and "sell" it so that hopefully it get integrated into
official tree.

Why new build system?

I wasn't happy with what bakefiles generate (mostly the unnecessary
recompile with gneerated makefile and the fact that there's only one
target and not standard release/debug build). I also plan on trying to
build a minimal version of gdk/linux (e.g. without xslt or xpath
support) and I felt that bakefiles won't let me experiment easily.

Why not fix bakefiles?

Bakefiles seem like a good idea but badly implemented and the project
is almost dead. It seemed faster to do it my way than learn enough
about bakefiles to fix the things that annoy me.

Why not cmake?

I would love to see cmake-based build for Gdk as well, but I don't know cmake
and doing it my way seemed simpler and faster (for me) than learning
about cmake.

What is it?

http://bugs.webkit.org/show_bug.cgi?id=11308

It's a simple python script that generates 2 Makefiles: release and
debug for gdk/linux, which I call Makefile.gdk.rel and
Makefile.gdk.dbg. I think it makes sense to keep both the script and
generated makefiles in the repository to make it easier for people to
compile gdk/linux version out-of-the-box. Makefiles don't change that
often so re-generating them is not a big deal.

I kept the nice tricks I've learned from bakefile-based makefiles.

I realize it's unusual to have a makefile per target - usually it's
done with one makefile with condititional code. One makefile saves dev
time if a makefile is being written by hand, but it doesn't matter in
case of a makefile generated by a script. Having separate makefiles
makes it easier to debug them because more things are spelled out.

What are advantages of this Makefile over bakefiles:
* builds both debug and release targets, in separate directories; other targets
easy to add
* no dependency on bakefiles, just python, for generating the makefiles
* makefile generated by bakefile causes unnecessary rebuilds (i.e. make after
make should do nothing, but it rebuilds some jsc files)
* one, non-recursive makefile (for some it might be disadvantage;
supposedly recursive makefile should be considered harmful)
* meta-description is much shorter (my script uses dir + list of
exceptions to specify files for the makefile while bakefiles/cmake
requires listing every file explicitely)

Disadvantages:
* doesn't build shared library but a standalone exe. Can be fixed in the future
if there's a need.
* doesn't generate wx/win makefiles, but... win is maintained by hand anyway,
there is no wx work at all, so the point is moot

Adding this build system to the tree doesn't mean that bakefiles have
to go - as long as there are people maintaining those system, there's
no harm in having more than one. I use this makefile for my builds and
I plan on maintaining it in the future.

-- kjk

As a sidenote, I don't understand why most makefile generators
(bakefile and cmake) require listing every file to build. My little
script uses directory + list of exceptions (files *not* to compile)
which makes for a dramatically more compact description of targets.