Including a C header which declares a variable called "new"?

Question

I'm trying to use the OpenCA (libPKI) library in a C++ application. However, when including the file pki_x509_data_st.h the following code fragment is encountered:

typedef struct pki_x509_callbacks_st {

 /* ---------------- Memory Management -------------------- */
 void * (*new)  (void    );
 void   (*free) (void *x );
 void * (*dup)  (void *x );

This won't compile because of the "new" pointer declaration.

How can I make it work?

Update
After renaming the "new" variable I've encountered some new problems ("using typedef name after struct" etc.. ). I want to avoid changing too much of the old C code (modifying library headers somehow makes me feel nervous) so I decided just create a minimal isolation layer instead.

Do you have the source for the library? – Apr 19 '10 at 12:58 — , Apr 19 '10 at 12:58
@Neil: yes, it's a completely open source library. – StackedCrooked Apr 19 '10 at 13:03 — StackedCrooked, Apr 19 '10 at 13:03
Just change the name in the header and the source then. – Apr 19 '10 at 13:05 — , Apr 19 '10 at 13:05

score 6 · Answer 1 · answered Apr 19 '10 at 13:03

6

#define new its_reserved_dammit
#include <pki_x509_data_st.h>
#undef new

I suspect that the linker will be upset about it, though.

However, using a C library which isn't prepared for usage from C++, the linker will complain anyway, since the headers are missing the important extern "C" wrappers anyway...

answered Apr 19 '10 at 13:03

sbi

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Could the down-voter please explain what's wrong with my answer? – sbi Apr 19 '10 at 13:16

score 4 · Answer 2 · answered Apr 19 '10 at 13:04

4

Try this:

#define new mynew
extern "C"
{
#  include "pki_x509_data_st.h"
}
#undef new

What you should also do is change the file and submit a bug together with your patch.

answered Apr 19 '10 at 13:04

Eddy Pronk

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score 2 · Accepted Answer · answered Apr 19 '10 at 12:59

If you can get away with it, rename it to something that's not a reserved word in C++. Chances that that you might end up having to rebuild the whole library and apply your "fix" there as well.

I'd be looking into constructing an isolation layer between your C++ code and the C library, potentially a bit of C code that only exposes the functions you need to use and completely isolate you from the rest.

Oh, and by the way - that's a function pointer declaration, not a variable declaration. Just to clear this up...

score 0 · Answer 4 · answered Apr 19 '10 at 12:56

0

It's a reserved word in C++. Rename it to "myNew" or something.

answered Apr 19 '10 at 12:56

Jim Buck

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Including a C header which declares a variable called "new"?

4 Answers4