With the static instances method, all instances are placed within the current compilation unit. As a consequence, templates are reinstantiated during each recompilation; instances are not saved to the template repository.
The disadvantage of this method is that it does not follow language semantics and makes substantially larger objects and executables.
Instances receive static linkage. These instances will not be visible or usable outside the current compilation unit. As a result, templates might have identical instantiations in several object files. Because multiple instances produce unnecessarily large programs, static instance linkage is suitable only for small programs where templates are unlikely to be multiply instantiated.
Compilation is potentially faster with static instances, so this method might also be suitable during Fix-and-Continue debugging. (See Debugging a Program With dbx.)
Specify static instance linkage with the -instances=static compiler option.