No segfault -> null == ""

[Qian Xu]

Hi All,

When I was trying to learn how char-array works, I found something
unexpected.

-------------------------- code ------------------------------
module string_test;

void main()
{
  // test 1
  assert(null == "", "null is empty"); // No segfault

  // test 2
  char[] test; // test = null;
  assert(test is null, "undefined_string is null");
  assert(test == "", "undefined_string (null) is empty");
  assert(test.length == 0, "undefined_string.length == 0");

  // test 3
  test = "";
  assert(test !is null, "empty_string is NOT null");
  assert(test == "", "empty_string is empty");
  assert(test.length == 0, "empty_string.length == 0");

  // test 4
  test = "hello";
  assert(test !is null, "non_empty_string is NOT empty");
  assert(test != "", "non_empty_string is NOT empty");
  assert(test.length > 0, "non_empty_string.length > 0");
}
-------------------------- code ------------------------------

I just wondered, why the first test does not lead to a segfault. Is this an
undocumented compiler feature? I have tested it with gdc and gdmd. Both no
segfault.


--Qian