On Tuesday, 25 June 2019 at 11:16:47 UTC, Jonathan M Davis wrote:
On Tuesday, June 25, 2019 1:32:58 AM MDT Eugene Wissner via
Digitalmars-d- learn wrote:
struct Container
{
}
static struct Inserter
{
private Container* container;
private this(return scope ref Container container)
@trusted
{
this.container = &container;
}
}
auto func()()
{
Container container;
return Inserter(container);
}
void main()
{
static assert(!is(typeof(func!())));
}
The code above compiles with dmd 2.085, but not 2.086 (with
-preview=dip1000). What am I doing wrong?
You're storing a pointer to a scope variable. That's violating
the entire point of scope. If something is scope, you can't
store any kind of reference to it. And since container is a
local variable in func, and Inserter tries to return from func
with a pointer to container, you definitely have an @safety
problem, because that pointer would be invalid once func
returned.
- Jonathan M Davis
So you're saying that func() shouldn't compile? And it is exactly
what the assertion in the main function does: it asserts that the
function cannot be instantiated. And it was true for 2.085 but it
can be instantiated with 2.086.
