`with` across function calls

[Simen Kjærås]

On Friday, 18 January 2019 at 12:35:33 UTC, Nicholas Wilson wrote:
> void bar(with Global g)
> {
>
> }

How does this work with nested calls? e.g.

struct Global {
     int n;
}
void foo() {
     auto g = Global(0);
     with (g) {
         bar();
     }
}
void bar(with Global g) {
     assert(g.n == 0);
     baz();
     assert(g.n == 0); // g is not overwritten by baz's new g
}
void baz() {
     auto g = Global(1);
     with (g) {
         qux();
     }
}
void qux(with Global g) {
     assert(g.n == 1); // use the nested g
}


If my intuition is correct, the above should compile with no 
asserts triggered.
I further expect that attempting to call bar() or qux() outside a 
with(g) will fail:

unittest {
     bar(); // Error: calling bar requires Global g in surrounding 
with() scope.
     Global g;
     bar(); // Error: Global g found in surrounding scope, but not 
used in with().
}

--
   Simen