Linking errors when compiling using Microchip C30 compiler for Openpicus - c

Question

I am compiling a project with lot of external libraries. The project has some warnings , but i believe that it should not hamper the creation of the .hex file. So when i compile the project I get a list of linking errors.
Compiling C:\liblwm2m\Libs\ExternalLib\heap.s
* Total program memory used (bytes): 0x28ef3 (167667) 64%
* Total data memory used (bytes): 0x360a (13834) 84%
x_object_device.o(.text+0x688):C:\liblwm2m\Libs\ExternalLib\object_device.c: undefined reference to `strdup'
x_object_device.o(.text+0x68a):C:\liblwm2m\Libs\ExternalLib\object_device.c: undefined reference to `strdup'
x_object_device.o(.text+0x6b6):C:\liblwm2m\Libs\ExternalLib\object_device.c: undefined reference to `strdup'
x_object_device.o(.text+0x6b8):C:\liblwm2m\Libs\ExternalLib\object_device.c: undefined reference to `strdup'
x_object_device.o(.text+0x6e4):C:\liblwm2m\Libs\ExternalLib\object_device.c: undefined reference to `strdup'
x_object_device.o(.text+0x6e6):C:\liblwm2m\Libs\ExternalLib\object_device.c: more undefined references to `strdup' follow
x_observe.o(.text+0x3c2):C:\liblwm2m\Libs\ExternalLib\observe.c: undefined reference to `object_read'
x_observe.o(.text+0x3c4):C:\liblwm2m\Libs\ExternalLib\observe.c: undefined reference to `object_read'
x_liblwm2m.o(.text+0x86):C:\liblwm2m\Libs\ExternalLib\liblwm2m.c: undefined reference to `strdup'
x_liblwm2m.o(.text+0x88):C:\liblwm2m\Libs\ExternalLib\liblwm2m.c: undefined reference to `strdup'
x_management.o(.text+0x48):C:\liblwm2m\Libs\ExternalLib\management.c: undefined reference to `object_read'
x_management.o(.text+0x4a):C:\liblwm2m\Libs\ExternalLib\management.c: undefined reference to `object_read'
x_management.o(.text+0xa6):C:\liblwm2m\Libs\ExternalLib\management.c: undefined reference to `object_create'
x_management.o(.text+0xa8):C:\liblwm2m\Libs\ExternalLib\management.c: undefined reference to `object_create'
x_management.o(.text+0x154):C:\liblwm2m\Libs\ExternalLib\management.c: undefined reference to `object_isInstanceNew'
x_management.o(.text+0x156):C:\liblwm2m\Libs\ExternalLib\management.c: undefined reference to `object_isInstanceNew'
x_management.o(.text+0x16e):C:\liblwm2m\Libs\ExternalLib\management.c: undefined reference to `object_create'
x_management.o(.text+0x170):C:\liblwm2m\Libs\ExternalLib\management.c: undefined reference to `object_create'
x_management.o(.text+0x188):C:\liblwm2m\Libs\ExternalLib\management.c: undefined reference to `object_write'
x_management.o(.text+0x18a):C:\liblwm2m\Libs\ExternalLib\management.c: undefined reference to `object_write'
x_management.o(.text+0x1a2):C:\liblwm2m\Libs\ExternalLib\management.c: undefined reference to `object_execute'
x_management.o(.text+0x1a4):C:\liblwm2m\Libs\ExternalLib\management.c: undefined reference to `object_execute'
x_management.o(.text+0x1da):C:\liblwm2m\Libs\ExternalLib\management.c: undefined reference to `object_write'
x_management.o(.text+0x1dc):C:\liblwm2m\Libs\ExternalLib\management.c: undefined reference to `object_write'
x_management.o(.text+0x208):C:\liblwm2m\Libs\ExternalLib\management.c: undefined reference to `object_delete'
x_management.o(.text+0x20a):C:\liblwm2m\Libs\ExternalLib\management.c: undefined reference to `object_delete'
x_registration.o(.text+0x8c):C:\liblwm2m\Libs\ExternalLib\registration.c: undefined reference to `prv_getRegisterPayload'
x_registration.o(.text+0x8e):C:\liblwm2m\Libs\ExternalLib\registration.c: undefined reference to `prv_getRegisterPayload'
C:\Program Files\Microchip\MPLAB C30\bin\bin/pic30-coff-bin2hex.exe: a.cof could not be opened.
The system cannot find the file specified.
---------------------------------- COMPILING ERROR ---------------------------------------
Here the strdup function is in which is supported by openpicus and i have also declared it. What surprises me is that the program compiles correctly but throws linking errors. Any thoughts about this ?
Thanks in advance

Answer 1

These are the errors in the code
undefined reference to strdup'
undefined reference toobject_read'
undefined reference to object_create'
undefined reference toobject_isInstanceNew'
undefined reference to object_create'
undefined reference toobject_write'
undefined reference to object_execute'
undefined reference toobject_write'
undefined reference to object_delete'
undefined reference toprv_getRegisterPayload'
P.S. these are not warnings!!
The error indicates that there is no definition of the functions "strdup", ... , "prv_getRegisterPayload". The linker does not find the references to these routines, and it terminates with a link time error. No linking means no hex file produced, that is the standard behavior of all toolchains.
Check the libraries that you have attached to the project. Add the libraries that have references/definitions for these routines, and the code should then build fine.
A pseudo code that will produce a similar error is as:
extern void parabola ();
int main(void)
{
parabola (); // ERROR here "undefined reference to `parabola'
}
-- Where is the definition of the function parabola? Shouldn't it be
void parabola ()
{}
int main(void)
{
parabola (); // Builds like magic
}