Nested captured block looses scope and crashes compiler

[jhass]

def foo(&block)
  block.call
end

foo {
  a = "foo"
  foo {
    a.upcase
  }
}

[asterite]

Apparently the first block is considered a closure by the compiler, which is wrong. It'll be a good opportunity to clean up the closure detection algorithm, which is rather ugly now :-)

[jhass]

I guess this is the same one:

def foo(&block)
  block.call
end

foo do
  a = 1.5
  ->(x : Int32) { x + a }
end

[asterite]

Here's the smallest one that crashes the compiler:

->{ a = 1; ->{ a } }

Basically, a proc inside another one, the nested one being a closure inside the outer one. But the compiler thinks the outer one forms a closure over a, which is wrong, and then the codegen doesn't expect this and crashes.

I think it's easy to fix but I'd like to refactor some things while fixing this so the code is clearer.

[jhass]

Sure, take your time.