Where are the gcov symbols?

I just spent an incredible amount of time debugging a very similar error. Here’s what I learned:

• You have to pass -fprofile-arcs -ftest-coverage when compiling.
• You have to pass -fprofile-arcs when linking.

• You can still get weird linker errors when linking. They’ll look like this:

  libname.a(objfile.o):(.ctors+0x0): undefined reference to 'global constructors keyed to long_name_of_file_and_function'

This means that gconv’s having problem with one of your compiler-generated constructors (in my case, a copy-constructor). Check the function mentioned in the error message, see what kinds of objects it copy-constructs, and see if any of those classes doesn’t have a copy constructor. Add one, and the error will go away.

Edit: Whether or not you optimize can also affect this. Try turning on / switching off optimizations if you’re having problems with it.