[Issue 15862] dmd thinks functions are strongly pure despite mutable indirections in the return type

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=15862

--- Comment #7 from Walter Bright <bugzilla at digitalmars.com> ---
Yeah, my mistake. The compiler should consider @nogc when marking a pure
function as a common subexpression.

--