Flatten a range of static arrays

[Steven Schveighoffer]

On 2/7/20 6:10 PM, nullptr wrote:

> ```
> import std;
> 
> struct SomeRange
> {
>      int[3] val;
> 
>      enum empty = false;
> 
>      auto popFront() @safe {}
> 
>      ref auto front() @safe
>      {
>          return val;
>      }
> }
> 
> void main() @safe
> {
>      SomeRange().take(10).map!((return ref x) => x[]).joiner.writeln;
> }
> ```
> 
> I don't know how applicable this is to your use case, but this code will 
> compile and run under -dip1000.

I tried the AST button. for the front function I got:

return pure nothrow @nogc ref @safe int[3] front() return

Note the duplicate return attributes. When I type that in, it doesn't 
compile, the return at the front is invalid.

When I remove that return, I get a safety error. So something is weird 
about how the attributes are inferred. Either there is some magic 
attribute not being printed, or an attribute that can't be specified 
manually, or it's a bug.

-Steve