Re: [RFC] [gdb/build] Require c++17 compiler

[Pedro Alves <pedro@palves.net>]

On 2023-10-05 07:54, Tom de Vries via Gdb-patches wrote:
> Since gdb 8.0, we've required a c++11 compiler.
> 
> That allowed gdb to be compiled with gcc releases as far back as gcc 4.8,
> using an explicit -std=c++11 to override the default.
> 
> [ Gcc has the following defaults:
> - before gcc 6: c++98, and
> - for gcc 6-10: c++14, and
> - since gcc 11: c++17. ]
> 

Just a comment here:

> There are two arguments in favor of moving to requiring a newer c++ standard:
> - benefits can be had from using newer c++ features.  We're already using some
>   of those features using gdb-specific implementations.

...

> - when developing gdb on modern platforms with system compiler gcc >= 6,
>   people can accidentally use c++14/c++17 features in a patch, only to find out
>   post-commit that it breaks the build on a system with a compiler that only
>   supports c++11, which is inconvenient and takes time to fix.
>   [ This could be partially mitigated by if possible also forcing -std=c++11
>   for such compilers. ]

Whether to force -std=c++11 to avoid this had been discussed back in the C++11
transition as well, and we decided against back then.  The benefit of being able to
conditionally use newer C++ features, which may e.g., be a lot more efficient,
or the making sure our replacements don't deviate from actual standard components
(by actually using them when possible), outweighs the rare breakage concern, IMHO.