I just compiled some C++ code using G++ under ulimit -v 108032, but it didn't use much of the STL. For a simple example program using iostream, vector, unique_ptr, and std::string, I needed more, but had success with ulimit -v 262144: http://canonical.org/~kragen/sw/dev3/docentes.cc.

I'm not sure how much RAM you need to compile G++ itself, though. More, I imagine. I was definitely compiling versions of GCC long before I ever saw a machine with so much RAM as 1GB, but I am guessing you probably need at least 1GiB for recent versions, maybe 4GiB. LLVM is much heavier.

cproc/tcc/scc/etc are C compilers not c++.

If you want to compile a recent c++ compiler (gcc/clang), you must have already a c++ compiler (one of the biggest mistake in open source software ever was to move gcc to c++, clang doing the wrong thing right from the start...).

You can start to compile gcc 4.7.4, the last gcc compiler with buggy c++98 you could compile with a C compiler (you will need to patch it, and even unroll its full SDK), then you will have to compile at least 2 gccs to reach the last gcc. This insane mess is due to the infinite versions of c++ ISO "standard", introducing tons of feature creep which will force you to "upgrade" (mostly no real good reasons, namely developer tantrums, or planned obsolescence).

This is disgusting, Big Tech grade abomination of software engineering, shame on the people who did that and those in power who are not trying to fix it (probably the GCC steering committee).