Use T.any(Integer, Float, BigDecimal) as the return type for ActiveRecord calculation methods

[olivier-thatch]

Use T.any(Integer, Float, BigDecimal) as the return type for ActiveRecord calculation methods.

Closes #1850.

Motivation

See discussion in #1850.

Implementation

Updated ActiveRecordRelations compiler to use T.any(Integer, Float, BigDecimal) instead of Numeric as the return type for sum methods.

Some notes/thoughts:

• Should other calculation methods be updated accordingly? E.g. average, minimum, maximum, calculate
  • Yes ➡️ Done!
• BigDecimal is only available after require "bigdecimal" (and, in a future Ruby version, bigdecimal will switch from a default gem to a bundled gem). That's probably fine since bigdecimal is a dependency of activesupport, so presumably any Rails / ActiveRecord user already has the gem in their app.

Tests

Updated existing tests in spec/tapioca/dsl/compilers/active_record_relations_spec.rb

[egiurleo]

I'm fine keeping BigDecimal for now because most Rails users will have it loaded. We can improve that if somebody opens an issue about it!

I think we should update the other calculation methods so the entire RBI file is consistent. I imagine it would be confusing for someone to run into the issues you've been having (having to cast all the time) but only for certain methods.

[olivier-thatch]

@egiurleo I've updated the PR to use T.any(Integer, Float, BigDecimal) for all ActiveRecord calculation methods.