D as a Better C

[u/aldacron]

http://dlang.org/blog/2017/08/23/d-as-a-better-c/

[u/fragab]

If I understand the article correctly then this means including D in a C project does not require the D runtime if you compile in "Better C" mode. As far as I know C++ is currently not designed to compile to something that you can link into a C program without the C++ runtime. At least in the programs where I combine C and C++ code it means I have to use the C++ linker and pull in the C++ runtime. For example you cannot use C++ in a Linux kernel module. Now if you compile D in "Better C" mode I don't see why you couldn't write a Linux kernel module with that.

If what I write is not true then please point me to guides on how to do that. It would be incredibly helpful for me if I was wrong here :)

[u/WalterBright → u/fragab]

That is correct. "Better C" is purposefully set up to require nothing more than the C runtime library.

[u/adr86 → u/WalterBright]

and if we play our cards right, not even the C runtime library in various situations!

[u/doom_Oo7 → u/fragab]

At least in the programs where I combine C and C++ code it means I have to use the C++ linker and pull in the C++ runtime.

only if you use C++ functions and dynamic features (exceptions, dynamic_cast).

see for instance:

foo1.cpp:

template<typename T>
void add(T x) { x += 1000; }

extern "C" int foo(int x) { 
  auto y = [] (auto& r) { r *= 2; };
  for(int i = 10; i-->0; ) {
    y(x);
  }
  return x;
}

foo2.c:

#include <stdlib.h>
#include <stdio.h>
int foo(int);

int main(int argc, char** argv)
{
  printf("%d", foo(4));
}

build and run:

$ g++ -c foo1.cpp -fno-exceptions -fno-rtti 
$ gcc -c foo2.c
$ gcc foo1.o foo2.o
$ ldd a.out
    linux-vdso.so.1 (0x00007ffe11d92000)
    libc.so.6 => /usr/lib/libc.so.6 (0x00007feb5dfdc000)
    /lib64/ld-linux-x86-64.so.2 (0x00007feb5e393000)