Transitions to new language semantics

[surlymoor]

On Friday, 11 June 2021 at 11:27:03 UTC, Ola Fosheim Grøstad 
wrote:
> On Friday, 11 June 2021 at 07:36:47 UTC, Sönke Ludwig wrote:
>> [...]
>
> I am troubled in general by the implementation of incomplete 
> solutions and making them gradually available.
>
> I would find it much more reassuring if a comprehensive 
> solution was developed as a completely separate compiler 
> branch. Basically have a stable branch (as is), and then a 
> future branch that is considered unstable until all the corner 
> cases have been ironed out. This also allows more heavy 
> restructuring of compiler internals, like introducing an 
> appropriate IR (which is needed for things like borrowing or 
> ARC, if you want something solid).
>
> The cost of moving to a more complete solution after something 
> incomplete has been made official could break the camel's back.
>
> The piece-by-piece approach is a slippery slope.

Doesn't Rust do something like this? A problem I read concerning 
its ecosystem is the tendency to target nightly, and thus using a 
more stable branch of the compiler leaves one high and dry, so to 
speak.