Re: WIP: About CMake v2

On Tue, Sep 01, 2015 at 12:49:55AM -0400, Tom Lane wrote:
> Noah Misch <noah(at)leadboat(dot)com> writes:
> > On Fri, Aug 28, 2015 at 01:28:49PM -0300, Alvaro Herrera wrote:
> >> If it allows us to get rid of our custom MSVC scripts, it's a huge
> >> benefit, for sure -- that has been a huge pain in the neck since day
> >> one.
>
> > Moreover, I suggest beginning with a patch that replaces the src/tools/msvc
> > build system with CMake. One can test almost all Windows configurations using
> > two machines, so author and reviewer can test most everything. src/tools/msvc
> > has more defects than the GNU make build system, so the minimum-quality
> > acceptable replacement is easier to deliver. With CMake driving all MSVC
> > builds, it would be much easier to gradually extend to other platforms.
>
> mmm ... dunno about that plan. In the first place, you seem to be
> recommending that YUriy incorporate all the deficiencies of src/tools/msvc
> into his first draft and then hope somehow to fix them later.

No, src/tools/msvc is a poor source of implementation ideas. Implement the
CMake build in idiomatic CMake style. Write an initial patch sufficient so we
could delete src/tools/msvc in the same patch, and make little or no attempt
to cover other cases. That's my suggestion.

> In the
> second place, I think that the core problem here involves being sure
> we can still cover all the portability issues that have been laboriously
> hacked into the autoconf/gmake build system over nigh two decades.

I agree that the first patch should demonstrate the CMake programming
environment's sufficiency for open-ended portability adaptations. I doubt
demonstrating that requires actual porting to more than a platform or two.

> Starting from a build system that was designed to cover exactly one target
> platform, and has never been asked to do anything more than that, doesn't
> sound like a recipe for success there.

Fair point. Perhaps replace src/tools/msvc completely and build+install on at
least one reasonable GNU/Linux configuration?

A monolithic patch replacing the GNU make build system with a CMake build
system sounds far too hard to write and review; we should expect to maintain
those two build systems in parallel for awhile. Reconciling the MSVC and GNU
make build systems is a chronic problem today, so it would be a big plus to
have no more than two of MSVC, GNU Make and CMake build systems to maintain.