ports/86304: [PATCH] graphics/jpeg does not have 'extern "C"' for C++

[Craig Rodrigues]

>Number:         86304
>Category:       ports
>Synopsis:       [PATCH] graphics/jpeg does not have 'extern "C"' for C++
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    freebsd-ports-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Sun Sep 18 19:20:03 GMT 2005
>Closed-Date:
>Last-Modified:
>Originator:     Craig Rodrigues
>Release:        FreeBSD 7.0-CURRENT i386
>Organization:
>Environment:
System: FreeBSD dibbler.crodrigues.org 7.0-CURRENT FreeBSD 7.0-CURRENT #21: Sat Sep 10 19:15:12 EDT 2005 rodrigc at dibbler.crodrigues.org:/usr/obj/usr/src/sys/MYKERNEL1 i386


	
>Description:
	If jpeglib.h is included in a C++ program, the functions in
	libjpeg cannot be linked against, because the function prototypes
	are not decorated with 'extern "C"'

>How-To-Repeat:
If you put the following code snippet:
#include <stdio.h>
#include "jpeglib.h"
int main(int argc, char *argv[]) { jpeg_std_error(NULL); }

in a C file (test.c), and compile with:
gcc -I/usr/local/include test.c -L/usr/local/lib -ljpeg

it will compile and link fine.

If you rename the file to test.cpp, and compile with:
g++ -I/usr/local/include test.cpp -L/usr/local/lib -ljpeg

You will get a link error:
: undefined reference to `jpeg_std_error(jpeg_error_mgr*)'


>Fix:

The fix is to re define the EXTERN macro if you are compiling with
a C++ compiler.


Index: patch-jmorecfg.h
===================================================================
RCS file: patch-jmorecfg.h
diff -N patch-jmorecfg.h
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ patch-jmorecfg.h	18 Sep 2005 19:01:01 -0000
@@ -0,0 +1,15 @@
+--- jmorecfg.h.orig	Sun Sep 18 14:53:48 2005
++++ jmorecfg.h	Sun Sep 18 14:54:27 2005
+@@ -187,8 +187,11 @@
+ /* a function referenced thru EXTERNs: */
+ #define GLOBAL(type)		type
+ /* a reference to a GLOBAL function: */
++#ifdef __cplusplus
++#define EXTERN(type)		extern "C" type
++#else
+ #define EXTERN(type)		extern type
+-
++#endif
+ 
+ /* This macro is used to declare a "method", that is, a function pointer.
+  * We want to supply prototype parameters if the compiler can cope.
>Release-Note:
>Audit-Trail:
>Unformatted: