[CMake] How to build CMake so it works on an older Linux?

[suzuki toshiya]

Dear Eric,

# if anybody think "how C++11 environment should be prepared
# on legacy GNU/Linux" is off-topic and should be discussed
# in off-list, please let me know. I will do so.

Eric Wing wrote:
> Thanks for the responses. Yes, I just need this to run on Ubuntu 12.04
> (and some other old Linux's in that era). Yes, I think the probably is
> the libstdc++ dependency.
> 
> As pointed out, it is really hard to get a newer compiler on Ubuntu
> 12.04. I've been down this road before, and if memory serves, the gcc
> bootstrapping process to get a newer compiler doesn't seem to work
> with a compiler older than gcc 4.8. Same goes for clang, which also
> weirdly relies on gcc 4.8 to bootstrap itself.

At least, gcc-4.6.3, the last official gcc for Ubuntu-12.04, could
build gcc-4.8.5 manually (without shared libstdc++, so confused
dependency could be avoided). And, I could build cmake-3.11.0 by it.
Now I'm checking "make test".

If you can give the preferred prefix to install gcc-4.8.5 + cmake-3.11.0,
I would be able to a tarball of the binaries. but please prepare
some virus + malware checking :-)

Regards,
mpsuzuki

> Anyway, CMake seems to already know how to ship binaries that work
> across Linux distros. I'm pretty sure they just statically linked
> libstdc++ and libgcc. In fact, I just built it with -static-libstdc++
> -static-libgcc on a newer Linux and tested it on 12.04 and it seemed
> to work.
> 
> But I wanted to know for sure how CMake is building their own binaries
> in case there are subtle problems with what I did, and they have a
> completely different way of building it, e.g. statically libmusl for C
> and libc++ for C++, avoiding gcc entirely.
> 
> Also, I did not take care of the libssl, libcrypto, and libz
> dependencies. I'm curious in practice how much trouble these are. (My
> recollection with zlib is that it is extremely stable and they care a
> great deal about not breaking backwards compatibility. I don't know
> about the others.)
> 
> Thanks,
> Eric
>