The functions wxString::Format, wxString::Printf (and others indirectly) have become stricter about parameter types that don't match (format specifier vs. function parameters). So the bugs (that were already present in audacity before) become visible in wx3.0 as error message dialogs. I've checked all occurrences of Printf, wxPrintf, PrintfV, Format, FormatV, wxLogDebug and wxLogError systematically and made the type match.
Note: In Shuttle.cpp this patch supersedes one related change done in r13466 because a wxLongLong_t can be bigger than an int and in a generic function like "TransferLongLong" this should be taken into account.
He wanted to help so I asked if he wanted to track them down. He agreed and
found more than I probably would have. And he said there were more, but the
rest were questionable and since he works on Windows, wasn't able to actually
test.
I give a few of the ones he did find a go and they do indeed get rid of the
assertions.
(Basically, a 64-bit/32-bit issue, easily resolved with a typecast.)