Unresolveable fallthrough functions


I’m following the Kaleidoscope tutorial (which is very good btw) and am having difficulties having function calls for functions that haven’t been defined getting resolved to plain C++ functions. In the tutorial (end of chapter 4), executing “extern putchard(x); putchard(120);” should execute the corresponding C++ function defined in the same file. Unfortunately in my case it only produces the following error:

ERROR: Program used external function ‘putchard’ which could not be resolved!

Any idea of what could be wrong?