7.2.2 Whole-Class Instantiation

The compiler usually instantiates members of template classes independently of other members, so that the compiler instantiates only members that are used within the program. Methods written solely for use through a debugger will therefore not normally be instantiated.

There are two means to ensure that debugging members are available to the debugger.

• First, write a non-template function that uses the template class instance members that are otherwise unused. This function need not be called.

• Second, use the -template=wholeclass compiler option, which instructs the compiler to instantiate all non-template non-inline members of a template class if any of those same members are instantiated.

The ISO C++ Standard permits developers to write template classes for which all members may not be legal with a given template argument. As long as the illegal members are not instantiated, the program is still well formed. The ISO C++ Standard Library uses this technique. However, the -template=wholeclass option instantiates all members, and hence cannot be used with such template classes when instantiated with the problematic template arguments.