• via Digitalmars-d-bugs (43/43) Jun 28 2016 https://issues.dlang.org/show_bug.cgi?id=16216

via Digitalmars-d-bugs <digitalmars-d-bugs puremagic.com> writes:

https://issues.dlang.org/show_bug.cgi?id=16216

          Issue ID: 16216
           Summary: struct equality compares padding
           Product: D
           Version: D2
          Hardware: x86_64
                OS: Linux
            Status: NEW
          Keywords: wrong-code
          Severity: normal
          Priority: P1
         Component: dmd
          Assignee: nobody puremagic.com
          Reporter: ag0aep6g gmail.com

----
struct Result
{
    int value = 0;
    ubyte len = 0;
}

void stompStack(ubyte val) { ubyte[1024] x = val; }

Result resultWithGarbagePadding()
{
    Result result = void;
    result.value = 0;
    result.len = 0;
    return result;
}

void main()
{
    Result r;
    stompStack(1);
    Result s = resultWithGarbagePadding();

    assert(s.tupleof == r.tupleof); /* passes, ok */
    assert(*cast(ubyte[5]*)&s == *cast(ubyte[5]*)&r); /* passes, ok */

    assert(s == r); /* fails, should pass */
    assert(s is r); /* fails, should probably pass */
}
----

Spec says [1]: "Equality for struct objects means the logical product of all
equality results of the corresponding object fields."


[1] https://dlang.org/spec/expression.html#EqualExpression

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