Template Instantiation

[Joe Buck]

> > On both of these systems, it works pretty much like it does with Borland
> > C++.  All needed templates are instantiated in each object file, but
> > weak symbols are used.  At link time, one weak symbol is used as the
> > definition.  If you have a recent GNU ld, the duplicate definitions, if
> > any, get stripped out and are not included in the binary.  If you have
> > an older linker or are using the Solaris linker, everything works, but
> > your executable may contain extra copies of some functions.
> 
> This just does not work at all:
> 
> CXXFLAGS = -DDEBUG=0 -DLINUX_LIBC6 -pipe -frtti -Wno-reorder \
> -Wno-unused 
> 
> I get lots and lots of undefined symbols, all of them from
> templates.

I didn't state something because I assumed you knew it: the compiler
must see the definitions of your template functions, not just their
declarations.  Definitions must be visible at the point of use.  With
or without -frepo, the compiler and linker won't go looking in other
files for template definitions.