Why is C++ initial allocation so much larger than C's?

Question

When using the same code, simply changing the compiler (from a C compiler to a C++ compiler) will change how much memory is allocated. I\'m not quite sure why this is and would

Answer 1

Neither GCC nor Clang are compilers -- they're actually toolchain driver programs. That means they invoke the compiler, the assembler, and the linker.

If you compile your code with a C or a C++ compiler you will get the same assembly produced. The Assembler will produce the same objects. The difference is that the toolchain driver will provide different input to the linker for the two different languages: different startups (C++ requires code for executing constructors and destructors for objects with static or thread-local storage duration at namespace level, and requires infrastructure for stack frames to support unwinding during exception processing, for example), the C++ standard library (which also has objects of static storage duration at namespace level), and probably additional runtime libraries (for example, libgcc with its stack-unwinding infrastructure).

In short, it's not the compiler causing the increase in footprint, it's the linking in of stuff you've chose to use by choosing the C++ language.

It's true that C++ has the "pay only for what you use" philosophy, but by using the language, you pay for it. You can disable parts of the language (RTTI, exception handling) but then you're not using C++ any more. As mentioned in another answer, if you don't use the standard library at all you can instruct the driver to leave that out (--Wl,--as-needed) but if you're not going to use any of the features of C++ or its library, why are you even choosing C++ as a programming language?