Parser: parse var as Call evan if var is declared in call args

[makenowjust]

Fixed #4106

[makenowjust]

This change is useful in following case for example:

class Foo
  class_property foo : String = "hello"

  p foo
end

Currently this file causes compile error: read before assignment to local variable 'foo'. But, this behavior looks like a bug.

[asterite]

Could you use is_call_args instead? call_args? as a variable name should be a parse error (at least it's not allowed in Ruby, and in Crystal it looks weird). If we don't change it now we'll have to change it later when we fix the parser for this, but I don't want to encourage this names.

[asterite]

Maybe call_args_nest should just be incremented and decremented in the methods parse_call_args and parse_call_args_space_consumed? I don't think this is the right place to do it.

[asterite]

Thank you for this!

I think this change is OK. It's a breaking change, because if you have code similar to the spec you added:

macro debug_init(x)
  puts "initializing {{x.var}} to {{x.value}}"
  {{x}}
end

debug_init a : Int32 = 0
a

it will stop working (now it works). But I don't think that's a good usage for a macro, and in general we use var : Type to eventually declare the type of instance/class vars, never local vars.

I made a few comments, after that I'll review it again and probably merge this.

[makenowjust]

@asterite Thanks for reviewing. I fixed to incr/decr @call_args_nest inside of parse_call_args and parse_call_args_space_consumed.

[asterite]

@makenowjust Thank you! 💚