MakeMakefile#try_type

# File tmp/rubies/ruby-3.3.0/lib/mkmf.rb, line 1256
  def try_type(type, headers = nil, opt = "", &b)
    if try_compile(<<"SRC", opt, &b)
#{cpp_include(headers)}
/*top*/
typedef #{type} conftest_type;
int conftestval[sizeof(conftest_type)?1:-1];
SRC
      $defs.push(format("-DHAVE_TYPE_%s", type.tr_cpp))
      true
    else
      false
    end
  end