[mhh__]

https://github.com/dlang/dmd/blob/master/src/dmd/dtemplate.d

That must be why the implementation of D's templates, which are designed to be easier to implement than C++'s is at least 8337 lines?

edit: Clang's clocks in at about 11k lines (.cpp alone), I'm too scared to find out for GCC.

[formerly_proven]

GCC's cp/pt.c is around 30k lines. But I don't expect the implementation of templates to be this localized, sure, most of it is probably in that module, but a lot will be strewn about the code base, too.