D compiler need -nogc witch and document of library also need nogc button

[KnightMare]

On Tuesday, 11 June 2019 at 12:42:03 UTC, Adam D. Ruppe wrote:
> On Tuesday, 11 June 2019 at 10:24:05 UTC, KnightMare wrote:
>> people who are interested only in betterC/nogc shouldn't see 
>> documentation to api that they are not suitable.
>
> I've considered doing that before, but it is actually 
> impossible to get right in the general case due to attribute 
> inference.
>
> Consider `map`, for example. If you map a nogc function, map is 
> nogc. But if not, it isn't - it depends on what function the 
> user passes to it. So the documentation can not know for sure.

imo problem with nogc/betterc is more deeper.
lets suppose we already have rcstring class and man want to write 
func that returns slice of it.
char[] someStrProcess(...) {
   rcstring tmp = "hello" ~ rcreadln; // somehow we got rcstring
   return tmp[5..$-5];
}
with current slise (struct{.ptr, .length}) we have a problem - 
data of tmp we'll be freed at function exit and current slice 
will ref to garbage. so compiler should forbid such situation.
this is not very well coz people read four current books where 
the slices were colorfully described, but for some reason a 
person cannot use them. they will come to forum and will ask 
another clarifying questions.

ok. we should returns some another 
slice(struct{.rcarray,.offset,.length}) which knows about RC:
rcslice<char> someStrProcess(...) {
   rcstring tmp = "hello" ~ rcreadln; // somehow we got rcstring
   return tmp[5..$-5]; // I dont want return whole string just 
part of it
   // should I return new rcstring as tmp.substr( 5, tmp.length-10 
)?
   // should we lose slices at all?
}
and this is something new that not described yet. well, it will 
be.
but maybe better write compiler that will returns rcslice as 
native new style slice char[] that knows about RC? some lang that 
mix of D and Swift which already used RC as ARC with familiar 
from book syntax.
and tada! we have two different language in one compiler, we have 
two different RT with one compiler. maybe it will be Phobos and 
Deimos.