Almost reached the limit of template instantiation depth

[Genomorf]

Hello. I have big transition table with a lot of states, events and actions. I know that you use some TMP to handle dependencies. Something like merge or join all deps into type_list and do aux::unique. It seems that i almost reached the limit of default (900) template instantiation depth during that operation.

During investigation of the issue, i used "-ftemplate-depth=500" and got compilation fail on instantiation of sm::deps_t type.

Result is an aux::type_list with 829 template parameters. Unique params are only 3. Example:
aux::type_list<dep_type1&, dep_type2&, logger_dep&, ... + 826 repeated params>

Num of dep_type1 params = 414.
Num of dep_type2 params = 414.
Num of logger_dep params = 1.

I can't just increase -ftemplate-depth to a larger number. gcc docs warns about it: https://gcc.gnu.org/onlinedocs/gcc-14.2.0/gcc/C_002b_002b-Dialect-Options.html

Set the maximum instantiation depth for template classes to n. A limit on the template instantiation depth is needed to detect endless recursions during template class instantiation. ANSI/ISO C++ conforming programs must not rely on a maximum depth greater than 17 (changed to 1024 in C++11). The default value is 900, as the compiler can run out of stack space before hitting 1024 in some situations.

Could you please clarify:

1. Is it expected and designed behavior to have so many repeated template parameters?
2. How can i reduce number of template parameters during instantiation of sm class? Let's say, i don't want to split the fsm into several smaller fsms.
3. Finally, do you recommend to increase -ftemplate-depth ignoring note of warning from gcc docs?