On Tuesday, 15 October 2013 at 21:37:40 UTC, Namespace wrote:
I get this error:
----
/d701/f223.d(11): Error: pure function 'f223.getA' cannot call
impure function 'f223.A.~this'
----
with this code:
----
import std.stdio;
struct A {
public:
~this() {
writeln("DTor");
}
}
A getA() pure nothrow {
return A();
}
void main()
{
A a = getA();
writeln("end of main");
}
----
But without pure and nothrow I get this output:
----
end of main
DTor
----
Why the compiler thinks that the function should/could call
A::~this?
It could have something to do with the fact that RVO is an
optimization *opportunity* that the compiler is allowed to go
for, even if it changes the program output.
Hoewever, being an *opportunity*, the compiler still has to make
sure the code is valid without said optimization, which in this
case, isn't: getA would destroy it's temporary after blitting it
on the stac, leading to an impure call.
