[DIP1000] Something I don't quite understand regarding 'scope'

[ag0aep6g]

On 29.06.20 02:28, Stanislav Blinov wrote:
> void local(Args...)(Args args)
> {
> }
> 
> void main() @safe
> {
>      import std.stdio;
>      scope int* p;
>      local(p);   // Ok
>      writeln(p); // Error: scope variable p assigned to non-scope 
> parameter _param_0 calling std.stdio.writeln!(int*).writeln
> }
> 
> The signatures of `std.stdio.writeln` and `local` are the same (see 
> `writeln` [1]). Yet, with '$ dmd -preview=dip1000' the call to `local` 
> compiles, while the call to `writeln` doesn't.

Since `local` and `writeln` are templates, the attributes for their 
parameters are inferred from their bodies. `local!(int*)` doesn't do 
anything with the parameter, so it's inferred as `scope`. 
`writeln!(int*)` apparently does something that prevents `scope` from 
being inferred.