[Issue 13045] New: TypeInfo.getHash should return consistent result with object equality by default

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=13045

          Issue ID: 13045
           Summary: TypeInfo.getHash should return consistent result with
                    object equality by default
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Keywords: wrong-code
          Severity: blocker
          Priority: P1
         Component: DMD
          Assignee: nobody at puremagic.com
          Reporter: k.hara.pg at gmail.com

This test case should succeed to run, but doesn't.

struct S
{
    int[] a;
}
void main()
{
    auto s1 = S([1,2]);
    auto s2 = S([1,2]);
    assert(s1 !is s2);
    assert(s1 == s2);
    assert(typeid(S).getHash(&s1) == typeid(S).getHash(&s2));
    // -> assert should pass, but doesn't
}


And, TypeInfo.getHash should also support composed hash calculation.

struct S
{
    size_t toHash() const nothrow @safe
    {
        assert(0);   // all getHash call should reach here
    }
}
struct T
{
    S s;
}
void main()
{
    import std.exception : assertThrown;

    S s;
    assertThrown!Error(typeid(S).getHash(&s));      // OK
    S[1] ssa;
    assertThrown!Error(typeid(S[1]).getHash(&ssa)); // OK
    S[] sda = [S(), S()];
    assertThrown!Error(typeid(S[]).getHash(&sda));  // OK

    T t;
    assertThrown!Error(typeid(T).getHash(&t));      // should pass
    T[1] tsa;
    assertThrown!Error(typeid(T[1]).getHash(&tsa)); // should pass
    T[] tda = [T(), T()];
    assertThrown!Error(typeid(T[]).getHash(&tda));  // should pass
}

--