| 1 |
On Thursday, 19 December 2013 02:41:55 CEST, heroxbd@g.o wrote: |
| 2 |
> I'd like to make an analogy to the version bump of gcc[1]. We (gentoo) |
| 3 |
> decide to support c++11 officially or not. If so, open a tracker bug to |
| 4 |
> push it globally. If not, patch lldb to support non-c++11, or leave it |
| 5 |
> up to the user to fiddle with the CXXFLAGS, where we only point the user |
| 6 |
> by to proper docs. |
| 7 |
|
| 8 |
To be honest, I do not really see a link between the "let's bring in a new |
| 9 |
version of compiler, it is a bit stricter in some situations, but these |
| 10 |
were bugs anyway, like missing headers or unfounded assumptions about |
| 11 |
memcpy()" with "let's support a new version of language which produces |
| 12 |
object files with different ABI". Perhaps a Python 2.6 vs. Python 3.3 is a |
| 13 |
better analogy? |
| 14 |
|
| 15 |
Anyway, GCC 4.8 is pretty clear that the C++11's support is still |
| 16 |
experimental [1] and subject to change [2]. The upstream developers have |
| 17 |
announced that they plan to break the ABI of the code using C++11 features |
| 18 |
in 4.9 [3]. |
| 19 |
|
| 20 |
Please also note that this is a very complicated problem, much more |
| 21 |
difficult than "code uses C++11's features -> it is incompatible". So far, |
| 22 |
the only known incompatibility is in the way STL is built. The impact of |
| 23 |
the other changes like the modified signatures of a couple of STL methods |
| 24 |
is not clear to me (and I did search for an ultimate answer). Even the |
| 25 |
document listing the breakage [4] does not provide a clear message "if you |
| 26 |
do $FOO, stuff breaks, but $BAR is completely safe". |
| 27 |
|
| 28 |
For example, there is no reason for not building e.g. Qt5 with C++11 |
| 29 |
support. In fact, limiting it to use just the C++98 features would be |
| 30 |
considered a regression from the perspective of a developer using Qt. |
| 31 |
|
| 32 |
Right now, it seems that we shall wait at least for GCC 4.9 to come and for |
| 33 |
upstream to decide how to solve this properly. |
| 34 |
|
| 35 |
Cheers, |
| 36 |
Jan |
| 37 |
|
| 38 |
[1] http://gcc.gnu.org/gcc-4.8/cxx0x_status.html |
| 39 |
[2] https://lwn.net/Articles/552831/ |
| 40 |
[3] https://lwn.net/Articles/552750/ |
| 41 |
[4] http://gcc.gnu.org/wiki/Cxx11AbiCompatibility |
Archives