从 C 访问内联 C++ function

Question

I'm trying to create C funciton wrappers for C++ and my goal is to make them inline. All the solutions on the inte.net say that when making an inline function in a library, just put the function definition in the header file. This won't work in this case though, since the functions contain code that will only compile in C++.

This example demonstrates the situation:

// box_c.cpp
#include "box.h"

extern "C" Square *new_Square(int width, int height){
    return new Square(width, height);
}



// box_c.h
void *new_Square(int width, int height);



// main.c
#include "box_c.h"

int main(void){
    void *s = new_Square(5, 5);
}

Wold it be possible to make new_Square inline in this case? (The wrapper is a static library).

Answer 1

Inlining means the compiler of the source where it is inlined needs to understand it on some level. C compilers don't understand C++ new . You can't do this. Leave it non-inlined, so a compiled version of the code can be linked without the compiler needing to understand C++ natively.

If the code (both library and final executable) is compiled with LTO enabled, it's possible the linker might inline the code at that point, but there are no guarantees there.

Answer 2

Obviously in general you cannot inline C++ code inside C code, they are two different languages.

So, either

• force the explicit instantiation of the C++ function in the compiled library,

• ensure that the C++ function is code-compatible with C and leave it in the header file as inline.