DMD CTFE Bug?

David d at dav1d.de
Fri Aug 17 09:40:58 PDT 2012


Am 17.08.2012 18:36, schrieb Dmitry Olshansky:
> On 17-Aug-12 20:27, David wrote:
>> I have this code: http://dpaste.dzfl.pl/dbe2a07f
>>
>> It works perfectly fine, except for `t!(2, 10)` and `t!(1, 10)`:
>>
>> // Expected:
>> [Vertex(-0.5, 0.5, 0.5, 0, 1, 0, 2, 10, 2, 10, 0, 0), Vertex(0.5, 0.5,
>> 0.5, 0, 1, 0, 3, 10, 3, 10, 0, 0), Vertex(0.5,  0.5, -0.5, 0,  1, 0, 3,
>> 9, 3, 9, 0, 0),
>>   Vertex(-0.5, 0.5, 0.5, 0, 1, 0, 2, 10, 2, 10, 0, 0), Vertex(0.5, 0.5,
>> -0.5, 0, 1, 0, 3, 9, 3, 9, 0, 0), Vertex(-0.5, 0.5, -0.5, 0, 1, 0, 2, 9,
>> 2, 9, 0, 0)]
>>
>> // Actual result:
>> [Vertex(-0.5, 0.5, 0.5, 0, 1, 0, 2, 10, 2, 10, 0, 0), Vertex(0.5, 0.5,
>> 0.5, 0, 1, 0, 3, 10, 3, 10, 0, 0), Vertex(0.5, -0.5,  0.5, 0, -1, 0, 6,
>> 3, 6, 3, 0, 0),
>>   Vertex(-0.5, 0.5, 0.5, 0, 1, 0, 2, 10, 2, 10, 0, 0), Vertex(0.5, 0.5,
>> -0.5, 0, 1, 0, 3, 9, 3, 9, 0, 0), Vertex(-0.5, 0.5, -0.5, 0, 1, 0, 2, 9,
>> 2, 9, 0, 0)]
>>
>> If I change `enum` in line 117 to `auto` it produces the expected result.
>>
>> Any ideas why this happens?
>
> Bug. There is no excuse for compiler to get different result during CTFE.

Great ...

>> (Btw. I wasn't able produce a smaller testcase)
> It's not thousands of lines either. But where does Vertex type comes from?

struct Vertex {
     float x;
     float y;
     float z;
     float nx;
     float ny;
     float nz;
     byte u_terrain;
     byte v_terrain;
     byte u_mask;
     byte v_mask;
     float u_biome;
     float v_biome;
}



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