Packed struct, size of field % 8 !=0, @byteOffsetOf does not include prior fields byte offset #5743

vegecode · 2020-06-28T19:00:59Z

test "@byteOffsetOf packed struct, fields cross byte boundary" {
    const P = packed struct {
        a: u9,
        b: u7,
    };

    std.testing.expectEqual(0, @byteOffsetOf(P, "a"));
    std.testing.expectEqual(1, @byteOffsetOf(P, "b"));
}

I reference this in my (failing) pull request #5713. What is the intended behavior?

This issue is linked to issue #5742 as they both come out of the same code section which is resolve_struct_type where the offsets are calculated.

daurnimator · 2020-06-28T23:56:01Z

Duplicate of #2627?

vegecode · 2020-06-29T11:52:04Z

Yep totally a duplicate. I would still like to know whether this test should pass or if it is a bug.

vegecode · 2020-07-09T12:29:04Z

Well I put in a pull request to fix the issue. It fixes byteOffset of. It's waiting to be reviewed and merged.

vegecode closed this Jul 9, 2020

ziglang / zig

Packed struct, size of field % 8 !=0, @byteOffsetOf does not include prior fields byte offset #5743

Packed struct, size of field % 8 !=0, @byteOffsetOf does not include prior fields byte offset #5743

vegecode commented Jun 28, 2020

daurnimator commented Jun 28, 2020

vegecode commented Jun 29, 2020

vegecode commented Jul 9, 2020

ziglang / zig

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Packed struct, size of field % 8 !=0, @byteOffsetOf does not include prior fields byte offset #5743

Packed struct, size of field % 8 !=0, @byteOffsetOf does not include prior fields byte offset #5743

Comments

vegecode commented Jun 28, 2020

daurnimator commented Jun 28, 2020

vegecode commented Jun 29, 2020

vegecode commented Jul 9, 2020

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