6.1 Writing libraries for C++
Creating libraries of C++ code should be a fairly straightforward
process, because its object files differ from C ones in only three ways:
- Because of name mangling, C++ libraries are only usable by the C++
compiler that created them. This decision was made by the designers of
C++ in order to protect users from conflicting implementations of
features such as constructors, exception handling, and RTTI.
- On some systems, the C++ compiler must take special actions for the
dynamic linker to run dynamic (i.e., run-time) initializers. This means
that we should not call ld directly to link such libraries, and
we should use the C++ compiler instead.
- C++ compilers will link some Standard C++ library in by default, but
libtool does not know which are these libraries, so it cannot even run
the inter-library dependence analyzer to check how to link it in.
Therefore, running ld to link a C++ program or library is deemed
Because of these three issues, Libtool has been designed to always use
the C++ compiler to compile and link C++ programs and libraries. In
some instances the
main() function of a program must also be
compiled with the C++ compiler for static C++ objects to be properly