Is there a gcc option to assume all extern “C” functions cannot propagate exceptions?

Question

Is there any way, short of putting an attribute on each function prototype, to let gcc know that C functions can never propagate exceptions, i.e. that all functions declared ins

Answer 1

Side note:
Are you sure telling the compiler "all these funcs never throw" is exactly what you want ?

It's not necessarily so that extern "C" ... functions cannot propagate/trigger exceptions. Take a case in point:

class Foo {
public:
    class Away {};
    static void throwaway(void) { throw Away(); }
}

extern "C" {
    void wrap_a_call(void (*wrapped)(void)) { wrapped(); }
}

int main(int argc, char **argv)
{
    wrap_a_call(Foo::throwaway);
    return 0;
}

Compiling and running this creates a C-linkage function wrap_a_call() which, when called like above, will happily cause an exception:

$ ./test
terminate called after throwing an instance of 'Foo::Away'
Abort(coredump)

I.e. there can be "exception leakage" with extern "C" (through invoking function pointers) and just because you're using/invoking extern "C" functions in a particular place in C++ doesn't guarantee no exceptions can be thrown when invoking those.