“It is never a compiler error”

Re:“It is never a compiler error” by nv-vn on Tuesday November 14, 2017 @07:47PM (#15700635)

Something similar happened to me a while back in Mono/C#. I think it was the order of assignments for an unused variable changed the results of the code. Something like:

    int x = 0;
    int y = 2;
    DoSomething(); // Didn't run with x before y

I can't recall if I ever reported it or bothered looking into it, but a friend ran into a similar issue around the same time and it was really confusing, but it was resolved by changing some configuration (different compiler version or flags I think).

Only other time I bumped into it was in Idris, which is to be expected frankly.

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Re:“It is never a compiler error” by ethbro on Tuesday November 14, 2017 @11:39PM (#15701495)

From what I remember of a deep dive post I read on this once, the ordering type bug / no-bug situations tend to be the result of incorrect optimizations. Changing the ordering will sometimes make the code look just different enough to go down a different (not bugged) optimization path.

If you ever catch them still there with a "no optimizations" flag, then that's a pretty serious bug!

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