MakeMakefile#what_type?

# File tmp/rubies/ruby-3.4.1/lib/mkmf.rb, line 1624
def what_type?(type, member = nil, headers = nil, &b)
  m = "#{type}"
  var = val = "*rbcv_var_"
  func = "rbcv_func_(void)"
  if member
    m << "." << member
  else
    type, member = type.split('.', 2)
  end
  if member
    val = "(#{var}).#{member}"
  end
  prelude = [cpp_include(headers).split(/^/)]
  prelude << ["typedef #{type} rbcv_typedef_;\n",
              "extern rbcv_typedef_ *#{func};\n",
              "rbcv_typedef_ #{var};\n",
             ]
  type = "rbcv_typedef_"
  fmt = member && !(typeof = have_typeof?) ? "seems %s" : "%s"
  if typeof
    var = "*rbcv_member_"
    func = "rbcv_mem_func_(void)"
    member = nil
    type = "rbcv_mem_typedef_"
    prelude[-1] << "typedef #{typeof}(#{val}) #{type};\n"
    prelude[-1] << "extern #{type} *#{func};\n"
    prelude[-1] << "#{type} #{var};\n"
    val = var
  end
  def fmt.%(x)
    x ? super : "unknown"
  end
  checking_for checking_message(m, headers), fmt do
    if scalar_ptr_type?(type, member, prelude, &b)
      if try_static_assert("sizeof(*#{var}) == 1", prelude)
        return "string"
      end
      ptr = "*"
    elsif scalar_type?(type, member, prelude, &b)
      unless member and !typeof or try_static_assert("(#{type})-1 < 0", prelude)
        unsigned = "unsigned"
      end
      ptr = ""
    else
      next
    end
    type = UNIVERSAL_INTS.find do |t|
      pre = prelude
      unless member
        pre += [["#{unsigned} #{t} #{ptr}#{var};\n",
                 "extern #{unsigned} #{t} #{ptr}*#{func};\n"]]
      end
      try_static_assert("sizeof(#{ptr}#{val}) == sizeof(#{unsigned} #{t})", pre)
    end
    type or next
    [unsigned, type, ptr].join(" ").strip
  end
end