https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118349
--- Comment #4 from Eric Gallager <egallager at gcc dot gnu.org> --- (In reply to Jonathan Wakely from comment #1) > (In reply to Eric Gallager from comment #0) > > For example, one could do -Wtemplate-depth=17 > > -ftemplate-depth=1024 to get a warning when the pre-C++11 limit is reached, > > but only actually fail if the post-C++11 limit is reached. > > Is this just a hypothetical example? It doesn't seem useful to me. > > No useful post-C++11 code will compile with the old limit, so every program > that uses libstdc++ would warn for -Wtemplate-depth=17 Yes, it's just a hypothetical example, I probably wouldn't actually use such a low value myself, but rather would determine an appropriate value experimentally on a project-by-project basis. (In reply to Jonathan Wakely from comment #2) > (In reply to Eric Gallager from comment #0) > > for users who are okay with template usage, but just > > don't want it to get out of hand. > > What does "get out of hand" mean? What unwanted consequence would you be > preventing with this check? > > The point of imposing a limit is so that buggy code with infinite recursion > will (hopefully) stop compiling before the system runs out of memory. So > it's a check to make accidental infinite recursion fail sooner, rather than > grind to a halt later. > > I'm not aware of a good use case for "I want some templates, but not too > much". It's mostly just a style thing; I find that the deeper template nesting gets in a project, the harder to understand I find it to be. Also excessive template depth can lead to code size bloat; I've seen this in some projects that abuse certain boost templates, for example. (In reply to Sam James from comment #3) > People already misunderstand the current option as well (PR65042). It'd just > get worse. This actually seems like a perfect example of a case where the user should have been using -Wtemplate-depth= (if it had existed) instead of -ftemplate-depth=.
