Dear Matlab Aficionados,
I am hoping someone can help me. I am trying to get Matlab 2016a loadlibrary() to accept loading a DLL that has an extern C declared header file with a forward declared struct inside. The same exact code works fin in older versions of Matlab like 2015a, but something changed in the 2016 version. I cannot use an #include statement inside the extern C declaration as a workaround by including the header file with the full definition of the struct in question because that full definition contains C++ classes. Is there anything I can do that will fix this issue? Can the older behavior of permitting forward declarations be reinstated in the future? It sure would save me a lot of code modification if I can find a solution.
This is what I mean:
inside "dll.h":
#ifdef __cplusplus
extern "C" {
#endif
typedef struct {
int a;
double *data;
} struct1;
struct struct2;
}
inside "dll_private.h"
#include "classes.h"
struct struct2
{
className objectName;
};
UPDATE: I just reinstalled Matlab 2015b to see if I can reproduce the issue. The issue exists there as well. I am thinking this error is compiler-specific. When I reinstalled Matlab, I removed a lot of previous Matlab-related things. I also removed the old Visual Studio 2012 and replaced with Visual Studio 2015. The error I get is this:
Error using loadlibrary
Building DLL_thunk_pcwin64 failed. Compiler output is:
cl -I"C:\Temp\include" /Zp8 /W3 /nologo -I"C:\Temp" -I"C:\Temp\inc"
"DLL_thunk_pcwin64.c" -LD -Fe"DLL_thunk_pcwin64.dll" DLL_thunk_pcwin64.c
C:\Temp\inc\DLL.h(727): error C2143: syntax error: missing '{' before '*'
C:\Temp\inc\DLL.h(733): error C2081: 'ForwardDeclaredStructName': name in formal parameter list illegal
My understanding is to list the compiler that Matlab can see, do "mex -setup":
mex -setup
MEX configured to use 'Microsoft Visual C++ 2015 Professional (C)' for C language compilation.
What can I do to get the original functionality that I used to have of being able to use loadlibrary with a forward declared struct pointer? Do I need to install Visual Studio 2012 and then change the default compiler to use it using "mex -setup"?
Update: I also tried 2015b (64bit) with Visual Studio 2012 DLL compiled in 64-bit (I used mex -setup to change to the VS2012 compiler after installing VS2012). I also recompiled the DLL with VS2012. The issue still persists. I am wondering if this is a 32 vs. 64-bit issue as Phil hinted at below.
Kind regards, Kris Walker
