title: Debugging vtable Linker Errors in GCC
body: <p>Now and then when using GCC I get cryptic errors like this:</p>
  
  <p>undefined reference to 'vtable for classname'</p>
  
  <p>When it's not caused by a missing library, this not-very-descriptive error message always causes me to dig through code files line by line to find the missing implementation for a virtual function.  Is there a way to make the linker tell me <em>which</em> virtual function it is missing, perhaps a flag or something?  Or is it maybe telling me but I don't understand what it's saying?</p>