Q43564: L2025: Symbol Already Defined Error Caused by SIGNAL.H in .QLB

Article: Q43564
Product(s): See article
Version(s): 4.00 4.00b 4.50
Operating System(s): MS-DOS
Keyword(s): ENDUSER | B_BasicCom buglist4.00 buglist4.00b buglist4.50 | mspl13_basic
Last Modified: 20-SEP-1990

LINKing C subfunctions into a QuickBASIC Quick library (.QLB) may
generate many "L2025: Symbol defined more than once" errors. This can
be caused when the C subfunction is compiled with the SIGNAL.H C
include file that comes with Microsoft QuickC version 2.00 and
Microsoft C Compiler versions 5.00, 5.10, and 6.00.

If the SIGNAL.H include file is not used, or if the C subfunction is
directly LINKed to the BASIC program when producing an .EXE file, the
errors do not occur.

Microsoft has confirmed this to be a problem in Microsoft QuickBASIC
versions 4.00, 4.00b, and 4.50; in Microsoft BASIC Compiler versions
6.00 and 6.00b (buglist6.00, buglist6.00b); and in Microsoft BASIC
Professional Development System (PDS) versions 7.00 and 7.10
(buglist7.00, buglist7.10). We are researching this problem and will
post new information here as it becomes available.

Below is the source code that, when LINKed into a Quick library, will
create the "Symbol defined more than once" errors.

C Routine
---------

/* SIGNAL.C */
/* Demonstration of signal.h failing with QuickBASIC 4.50 */

#include <signal.h>

int handler ()
{  }
void far testc()
{
    signal(SIGINT, handler);
}

Link Command
------------

   LINK /Q SIGNAL.OBJ,,,BQLB45.LIB;

The Quick library support module used in the above LINK line should be
BQLB45.LIB in QuickBASIC 4.50, BQLB41.LIB in QuickBASIC 4.00b or BASIC
Compiler 6.00b, BQLB40.LIB in QuickBASIC 4.00 or BASIC Compiler 6.00,
and QBXQLB.LIB in BASIC PDS 7.00 or 7.10.

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