Use whereis to print a list of all occurrences of function or class instantiations for a function or class template.
(dbx) whereis Array class template instance: a.out`Array<int> class template instance: a.out`Array<double> class template: a.out`template_doc_2.cc`Array
(dbx) whereis square function template instance: a.out`square(double, double*) function template instance: a.out`square(int, int*) function template: a.out`square