gistfile1.rb

def layout  
  root :my_root do
    add UIButton, :button_1 do
      constraints do
        top.equals(:superview)
        left.equals(:superview)
        width 30
        height 144
      end
    end
    
    add UIView, :side_view do
      constraints do
        top.equals(:button_1)
        left.equals(:button_1, :right).plus(5)
        height.equals(:button_1)
        right.equals(:superview)
      end
    end
  end
end

The above code gives the following runtime autolayout error:
Probably at least one of the constraints in the following list is one you don't want. Try this: (1) look at each constraint and try to figure out which you don't expect; (2) find the code that added the unwanted constraint or constraints and fix it. (Note: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't understand, refer to the documentation for the UIView property translatesAutoresizingMaskIntoConstraints) 
(
    "<NSLayoutConstraint:0x18ea1990 H:[UIButton:0x18e977b0(30)]>",
    "<NSLayoutConstraint:0x18ea1890 H:|-(0)-[UIButton:0x18e977b0](LTR)   (Names: '|':UIView:0x18e97560 )>",
    "<NSLayoutConstraint:0x18ea29e0 H:[UIButton:0x18e977b0]-(5)-[UIView:0x18e9e300](LTR)>",
    "<NSLayoutConstraint:0x18ea2c00 UIView:0x18e9e300.right == UIView:0x18e97560.right>",
    "<NSAutoresizingMaskLayoutConstraint:0x253711b0 h=--& v=--& H:[UIView:0x18e97560(0)]>"
)