Hello,
I wanted to try to create static lib in Nim and interface with C. However I cannot get it to work even when I tried to follow https://nim-lang.github.io/Nim/backends.html#interfacing-backend-code-calling-nim .
OS: Linux, Arch: amd64, Nim 1.6.0 and 1.4.8
Nim code in libnim.nim file:
proc add_int_in_nim*(a, b: cint): cint {.exportc.} =
result = a+b
echo "Echo in Nim: ", a, " + " , b, " = ", result
proc add_float_in_nim*(a, b: cfloat): cfloat {.exportc.} =
result = a+b
echo "Echo in Nim: ", a, " + " , b, " = ", result
proc add_double_in_nim*(a, b: cdouble): cdouble {.exportc.} =
result = a+b
echo "Echo in Nim: ", a, " + " , b, " = ", result
C code in main.c:
#include "libnim.h"
#include <stdio.h>
int main()
{
NimMain();
int a = 2;
int b = 3;
printf("Int: %d + %d\n", a, b);
int sum = add_int_in_nim(a, b);
printf("C printf - Nim calculated %d + %d = %d\n\n", a, b, sum);
float c = 2.0;
float d = 3.0;
printf("Float: %f + %f\n", c, d);
float sum2 = add_float_in_nim(c, d);
printf("C printf - Nim calculated %f + %f = %f\n\n", c, d, sum2);
double e = 2.0;
double f = 3.0;
printf("Double: %lf + %lf\n", e, f);
int sum3 = add_double_in_nim(e, f);
printf("C printf - Nim calculated %lf + %lf = %lf\n\n", e, f, sum3);
return 0;
}
Commands:
GCC output:
/usr/bin/ld: /tmp/cckiRwXc.o: in function `main':
main.c:(.text+0x9): undefined reference to `NimMain'
/usr/bin/ld: main.c:(.text+0x42): undefined reference to `add_int_in_nim'
/usr/bin/ld: main.c:(.text+0xc6): undefined reference to `add_float_in_nim'
/usr/bin/ld: main.c:(.text+0x165): undefined reference to `add_double_in_nim'
/usr/bin/ld: m: hidden symbol `add_float_in_nim' isn't defined
/usr/bin/ld: final link failed: bad value
collect2: error: ld returned 1 exit status
Do you have any idea what's wrong please?
GNU linkers (both default ld and gold) requires specific order of its inputs:
gcc -o m -Inimcache main.c libnim.a