Fix anonymous objects

[stereobooster]

Explanation. Trying to remove creation of anonymous objects

def test()
  "a" == "b"
end
GC.start
stat1 = GC.stat
1000_000.times do
  test
end
stat2 = GC.stat
p stat2[:count] - stat1[:count] # number of GC sweeps (minor + major)

^ This gives 147

# frozen_string_literal: true
def test()
  "a" == "b"
end
#...
p stat2[:count] - stat1[:count] # number of GC sweeps (minor + major)

^ This gives 0

---

def test(options = {})
end
GC.start
stat1 = GC.stat
1000_000.times do
  test
end
stat2 = GC.stat
p stat2[:count] - stat1[:count] # number of GC sweeps (minor + major) 

^ This gives 73

EMPTY_HASH = {}.freeze
def test(options = EMPTY_HASH)
end
#...
p stat2[:count] - stat1[:count] # number of GC sweeps (minor + major) 

^ This gives 0

It would be nice if ruby has magic comment for this case too, like # frozen_argument_hash: true instead of this EMPTY_HASH hack

[radar]

In the PR description could you please include a reason for these changes?

[stereobooster]

need to revert this

[stereobooster]

Updated description. Waiting for tests to finsih

[stereobooster]

• This one is merged Don't store translations for locales not set as available #391
• I hope this one will be merged too

Do you have any plans to do new release?

This one #392 needs more discussion.

PS. sometimes forget to do this: thank you for supporting this gem)

[radar]

Calling merge on a frozen hash will not work:

irb(main):001:0> a = {}.freeze
=> {}
irb(main):002:0> a.merge!(raise: true)
RuntimeError: can't modify frozen Hash
	from (irb):2:in `merge!'
	from (irb):2
	from /Users/ryanbigg/.rubies/ruby-2.4.2/bin/irb:11:in `<main>'

[stereobooster]

huh this means that it is not covered with tests, need to fix this

[stereobooster]

Wait a second. Yes .merge! will raise an error, because you can not mutate frozen object. But this code uses .merge without exclamation mark

[stereobooster]

Sequel also uses trick with EMPTY_HASH = {}.freeze, but they name it OPTS

[radar]

@stereobooster Would you mind rebasing this PR against master? I'd like to get it merged soon rather than leave it hanging around.

[stereobooster]

@radar sorry for delay. Rebased. Waiting for CI to pass

[radar]

Thank you a lot for coming back to this @stereobooster. Looks like your build is breaking because Rails master now requires Ruby 2.4+, but we were still running builds on Ruby 2.2, 2.3 for Rails master. I've fixed this now on master with 77067d6, and as long as that branch is green, your branch should be too 🤞

[radar]

Done!