Q59321: BASIC and C, /FPa, LINK L2025 "Symbol Defined More Than Once"

Article: Q59321
Product(s): See article
Version(s): 6.00 6.00b 7.00 | 6.00 6.00b 7.00
Operating System(s): MS-DOS | OS/2
Keyword(s): ENDUSER | SR# S900202-109 S_C buglist6.00 buglist6.00b buglist7.00 | mspl13_basic
Last Modified: 18-OCT-1990

When linking BASIC and C, where the C routine uses math functions
(such as SIN, COS) and was compiled with the /FPa (alternate math)
option and where the BASIC program was compiled with the /FPa option
and without the /O (stand-alone) option, several "L2025 Symbol defined
more than once" errors will occur. These errors are not affected by
/NOD or /NOE LINK options.

Any of the following three workarounds corrects the problem:

1. Compile the BASIC program with BC /o (stand-alone).

2. Compile BASIC and C with (default) BC /FPi.

3. Call all math functions from BASIC. (C can call BASIC externs to do
   math -- see below.)

Microsoft has confirmed this to be a problem in Microsoft C Compiler
versions 5.00 and 5.10 (buglist5.00, buglist5.10), in Microsoft BASIC
Compiler versions 6.00 and 6.00b for MS-DOS and MS OS/2, and in
Microsoft BASIC Professional Development System (PDS) version 7.00 for
MS-DOS and MS OS/2. We are researching this problem and will post new
information here as it becomes available.

The following code example causes the "symbol defined more than once"
errors when compiled as listed. The following are the compile and link
lines for the BASIC and C programs:

   BC /FPa testb;
   CL -c -AL -FPa test.c ;
   LINK /NOD /NOE testb+test,,,brt70anr llibcar;

When the code below is compiled and LINKed as specified, the following
LINK errors will occur:

   llibcar.LIB(fcall.ASM) : error L2025: __fpmath : symbol defined
      more than once

   llibcar.LIB(..\ccalle.ASM) : error L2025: __fpsignal : symbol defined
      more than once

For more information about calling C from BASIC, search in this
Knowledge Base using the following word:

   BAS2C

BASIC Program, TESTB.BAS
------------------------

DECLARE SUB test CDECL
CALL test

'Function used by C for workaround #3
FUNCTION BasSin#(a AS DOUBLE)
   BasSin#=SIN(a)
END FUNCTION

C Program, TEST.C
-----------------

#include <stdio.h>

extern double pascal BasSin(double near *);  // BASIC function for
                                             // workaround #3
void test()
{
double d=1.2;
printf("%f",sin(d));           // Comment this line and
//printf("%f",BasSin(&d));     // uncomment this line for workaround #3
}

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