Question

I’m playing around with a toolchain that seems to wrap gcc (qcc), but also uses g++ for a few things. This caused a bit of confusion when I couldn’t link libs I built with g++ using g(q)cc even though it was for the same architecture (due to missing lib errors). After a bit more research, I found that g++ is basically gcc with a few default flags and a slightly different interpretation mechanism for file extensions (there may be other differences I’ve glanced over). I’d like to know exactly which flags can be passed to gcc to amount to the equivalent g++ call. For instance:

g++ -g -c hello.cpp   // I know at the very least that this links in stl
gcc -g -c -???        // I want the exact same result as I got with g++... what flags do I use?

The way the tool chain is set up makes it sort of difficult to simply replace the gcc calls with g++. It’d be much easier to know which flags I need to pass.

Answer 1

The differences between using gcc vs. g++ to compile C++ code is that (a) g++ compiles files with the .c, .h, and .i extensions as C++ instead of C, and that (b) it automatically links with the C++ standard library (-lstdc++). See the man page.

So assuming that you’re not compiling .c, .h., or .i files as C++, all you need to do to make gcc act like g++ is add the -lstdc++ command line option to your linker flags. If you are compiling those other files as C++, you can add -x c++, but I’d advise you instead to rename them to use .cc or .ii files (.h can stay that way, if you’re using precompiled headers).