[Buildroot] RFC:?==?utf-8?q? Boost: depends guard for C++11 support

[Michael Nosthoff]

Hi all,

I'm currently looking into bumping the boost package to the newly released 1.84.0 version [0].

A lot of packages dropped the C++03 support in this release (and others will follow). 
So this means a lot of altering of dependent packages to propagate the C++11 dependency.

Now "C++11 Support" is a fuzzy term. Looking at the gcc cxx-status page [1] we see that the first version having full C++11 support was 4.8.1.
Since we don't have guards for patch versions this would mean BR2_TOOLCHAIN_GCC_AT_LEAST_4_9 would make sense.
So when looking at the depends-guards in the different packages we find a mixture of version claiming to guard for C++11 availability. The lowest version I found was gcc 4.7.

On the other hand the lowest gcc version in a toolchain at bootlin [2] I found is 5.4.
So the likelihood someone uses an older toolchain seems to be pretty low now.

So my question is: would it be okay to enforce a gcc version >= 4.9 for all boost libraries requiring c++11 or is it necessary to try out if lower gcc versions would also work for certain libraries?
Please advise!

Regards,
Michael


[0] https://www.boost.org/users/history/version_1_84_0.html
[1] https://gcc.gnu.org/projects/cxx-status.html#cxx11
[2] https://toolchains.bootlin.com/