[graue]

Three times, so:

    1. Old version compiles new version
    2. New version, compiled by old version, compiles new version
    3. New compiled by new-compiled-by-old compiles new version

I hadn't heard of this before and initially didn't see why #3 is special. But I guess the idea is, the output object code is a function of both the input source code and the compiler version. And those two are the same for #2 and #3. So you expect the output of both #2 and #3 to be identical, and if it's not, that's a bug in the compiler. Is that how it works?

[asdfs]

Yes, the third compile is effectively a single very large test.