[apiology]

Claude: This PR was written by Claude Code on behalf of @apiology.

Problem:

A tuple with its elements in the wrong order passes the type checker:

class Foo
  # @param x [Array(String, Integer)]
  # @return [void]
  def take(x); end

  # @return [void]
  def call_take
    # @type [Array(Integer, String)]
    y = [1, 'a']
    # no problem reported; should be: Wrong argument type for Foo#take: x expected Array(String, Integer), received Array(Integer, String)
    take(y)
  end
end

Tuples of the wrong length, such as Array(Integer) for Array(Integer, Integer), pass too, so a declared tuple guarantees nothing about which element is where.

Solution: Compare fixed type parameters of any type slot by slot and require equal counts, while implicit unions such as Array<A, B> and Hash still compare as unions and a list such as Array<String> fills a tuple only when its element type fits every slot.

The stricter check finds one wrong tag in Solargraph itself, fixed here: ParserGem::ClassMethods#process_node declared a two-element tuple but returns three.

Extracted from castwide/solargraph#1231, intersection types.

[apiology]

Claude: Opened upstream as castwide#1456.