Date: Sun, 18 Sep 2005 15:15:25 -0400 (EDT) From: Craig Rodrigues <rodrigc@crodrigues.org> To: FreeBSD-gnats-submit@FreeBSD.org Subject: ports/86304: [PATCH] graphics/jpeg does not have 'extern "C"' for C++ Message-ID: <200509181915.j8IJFPoQ037999@c-66-30-112-193.hsd1.ma.comcast.net> Resent-Message-ID: <200509181920.j8IJK3f9098304@freefall.freebsd.org>
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>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@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:
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