On Fri, 17 Feb 2023, 07:24 Julien D Arques via Gcc-help, < gcc-help@xxxxxxxxxxx> wrote: > Hi, > I just finished a project that required to generate a static library out of > heavily templated code. > Why? > It has been a productivity nightmare and will be hard to extend if needs > be. > Many "extern template XXX" in .hpp and corresponding "template XXX" in .cpp > that killed my day (many possible type combinations). > But why did you do that? > That need may happen again in a future project and I really don't want to > reiterate what I did. > > Maybe modules will help but I need a solution that can be applied now. > > Do we have a hack in GCC to avoid this pitfall? > Just don't do it. Templates are implicitly instantiated as needed. Why do you need them defined in the static library, instead of letting users instantiate them as needed when compiling the headers? If you're doing it to make compiling those headers faster, that's a valid choice you've made, but you're trading more work for you when creating the library vs less work for the compiler when using the library. If you choose to do that, then I'm afraid there's no short cut to avoid doing the extra work. One alternative would be to define the entry points to the library API as non-template functions, and then just let the templates be implicitly instantiated for the definitions of those functions in the library. But that would mean designing a different API and that might be just as much work (if it's even practical to do that).
