Re: [Chicken-users] undefined reference to `C_numbers_toplevel'

[Jim Ursetto]

On Nov 23, 2012, at 3:59 PM, Peter Bex wrote:

> On Fri, Nov 23, 2012 at 12:27:29PM -0800, Miguel Fernandez wrote:

>> I get the following error:
>> 
>>    main.o: In function `C_toplevel':
>>    main.c:(.text+0x1c2): undefined reference to `C_numbers_toplevel'
>>    collect2: ld returned 1 exit status
> 
> I'm not sure why that happens.  I guess it's caused by the "uses" switch
> which assumes you're statically linking?

Essentially.  -uses generates a call to C_numbers_toplevel() to initialize the 
unit, but that can't be resolved as it's not in a numbers.o or -lnumbers file 
passed to the linker.  Rather, numbers' toplevel is resolved later via 
dlopen(3) + dlsym(3).

Note that the numbers toplevel is referred to as C_toplevel() when using 
dynamic loading, but as C_numbers_toplevel() by -uses, since it has to be 
unique in the latter case.  (The C_numbers_toplevel() code is generated by 
-unit.)  This name difference means you can't contrive to link the numbers.so 
module directly into your program and use it via -uses instead of (use); not to 
mention bypassing the module import code.

tl;dr: Don't you use -uses, for -uses uses you.

Jim