2016-08-22 18:25 GMT+02:00 Jonathan Wakely <jwakely.gcc@xxxxxxxxx>: > On 22 August 2016 at 17:16, Tamás Kiss wrote: >> Hi Jonathan, >> >> Thanks for the answer! I also found the GCC ABI compatibility wiki >> page you mentioned, that's why I had concerns. At least these seem to >> be real issues for us: > > Based on what, just the GCC versions? Yes, as the others are not present in 4.8.3. By "real issues" I only meant "real issues to check", not that they are in fact present in the code. >> * `vector::data()`'s return type changes from `pointer` to `_Tp*` >> [gcc-4.6 - ...] > > For this to be an issue you need to be using the non-standard > vector::data() member (which is not part of C++03) with custom > allocators that use custom pointers. If you're not doing hat it's not > an issue. You're right, I was thinking about string::data(), I did not realize it is actually vector::data(). >> * `std::operator-(reverse_iterator)` and >> `std::operator-(__normal_iterator)` [gcc-4.4 - ...] >> * `istreambuf_iterator::reference` changes from `_CharT&` to `_CharT` >> [gcc-4.7 - ...] > > These are even more unlikely to be real issues in practice. Right again: I was thinking that we use the Boost 3PP with streams extensively, but of course we'll recompile Boost to C++11 anyway, so it's also not an issue. Boost is one of the libraries that I expect to work in C++11 without issues. >> This also, but at least it would cause compilation error: >> * Types with node allocators, like `deque` and lists, maps and sets >> [... - gcc-5] >> >> Based on the wiki page, I'm not sure how we could pinpoint the root >> cause if any of the above issues would be triggered in our program, >> especially if they would manifest in some runtime fault. > > As the top of the page says, you can check the symbols in your objects > and libraries to see if any problematic ones are present. We'll definitely do that. It's just that I still have the feeling that we're doing some black magic with all these compatibility checks. Anyway: if it's stupid but it works, it ain't stupid. :)
