Hackly mix C/C++ syntax in single file?

Question

I am assigned to port a big project from a dialect of C99 to Visual C++ 2013.

The dialect of C99:

When C99 and C++ have different behaviors, choose C++.
Supports some C++ features, e.g. function/operator overloading.
Supports some C99 features, e.g. compound literals, variadic macros, and designated initializer.

Before getting stuck, I wanna know if we can write C99/C++ mixed code in VS2013?

It must be compiled on both compilers, I guess there might be some amazing pragmas like

 struct T {
     int data;
 };
 #pragma CompiledByC99_begin
 struct T tmp = { .data = 1 };
 #pragma CompiledByC99_end

Unfortunately, nothing found after Googling. Does such hack exist in VS2013?

I dont know if you can really do this with vs, I would go with CMake (supported by vs), take a look over it, you can modify the build behaviour with it as you need — Netwave, Feb 25 '16 at 08:53
The code you posted doesn't make sense, because you certainly don't want `.data` to be initialized to `1` in one compiler, and uninitialized in the other one. What you *can* do is define certain macros depending on the compiler, which is basically the standard way for cross-compiler support. This also includes compiler-specific keywords (like `far` or `near` for embedded firmware programming). Projects sometimes even define their own entire sets of defines for all primitive types (like `U08`, `S08`, `U16` for `byte`, `signed byte` or `signed short`). Btw, why not VS2015 community edition? — vgru, Feb 25 '16 at 08:57
Define what you mean by porting... Are you expected to rewrite genuine C++11 to replace C99 code? Also, did you try to compile your C99 code with your C++11 compiler? Then, what concrete issues did you encounter (be specific, e.g. give compiler errors)? So **edit your question** to improve it, it is currently unclear. — Basile Starynkevitch, Feb 25 '16 at 09:00
If I am trying to read between the lines, project was compiled with C++ compiler which supported some of C99 features as an extension? Because C99 compiler that supports funciton/operator overloading sounds horrible. What compiler were you using originally? — user694733, Feb 25 '16 at 09:14
This looks like a case where the introduction of a few macro's may reduce the clutter quite a bit. But stuff like the ` = { .data = 1 }` should just be rewritten as a normal initialization followed by member assignment. — MSalters, Feb 25 '16 at 09:15
IMHO: Don't mix, make it standard compliant C++ (C++11 or even C++14, though both will probably be hard with VS2013) for as much as you can, compile these parts with a (standard compliant) C++ compiler, and compile the rest with the compiler handling your "C99 dialect", then link everything together. This will help you in the long run. — Daniel Jour, Feb 25 '16 at 09:51

score 2 · Answer 1 · edited Jun 20 '20 at 09:12

You can only use a limited selection of C99 features in Visual Studio 2015 and even less in 2013 (see this question for reference)

Quote from MSDN Blog entry related to your needed features:

Additionally, some C99 Core Language features will be implemented in 2013 RTM:

C99 _Bool

C99 compound literals

C99 designated initializers

C99 variable declarations

So, depending on what exactly you need, you may be able to do it without any hack

score 0 · Accepted Answer · answered Feb 25 '16 at 09:07

If you need to change some small portions of code to make them compilable by MSVC2013, you can use the _MSC_VER. It is defined for MSVC compilers and has integer value 1800 for VC 2013.

So you can use

#ifdef _MSC_VER
// code compilable under MSVC
#else
// other dialect
#endif

(Refs on MSDN)

Hackly mix C/C++ syntax in single file?

2 Answers2