gold is an ELF linker.  It is intended to have complete support for
ELF and to run as fast as possible on modern systems.

It is written in C++.  It is (intended to be) a GNU program, and
therefore follows the GNU formatting standards as modified for C++.
Source documents in order of precedence:
    http://www.gnu.org/prep/standards/
    http://gcc.gnu.org/onlinedocs/libstdc++/17_intro/C++STYLE
    http://www.zembu.com/eng/procs/c++style.html

The linker is intended to have complete support for cross-compilation,
which still supporting the normal case of native linking as fast as
possible.  This makes the code more complex.

Many functions are actually templates whose parameter is the ELF file
class (e.g., 32 bits or 64 bits).  The code is the same, but we don't
want to pay the execution time cost of always using 64-bit integers if
the target is 32 bits.