On Tuesday, 3 December 2019 at 07:12:18 UTC, Basile B. wrote:
I wish something like this was possible, until I change the
return type of `alwaysReturnNull` from `void*` to `auto`.
---
class A {}
class B {}
auto alwaysReturnNull() // void*, don't compile
{
writeln();
return null;
}
A testA()
{
return alwaysReturnNull();
}
B testB()
{
return alwaysReturnNull();
}
void main()
{
assert( testA() is null );
assert( testB() is null );
}
---
OMG, isn't it nice that this works ?
I think that this illustrates an non intuitive behavior of auto
return types.
One would rather expect auto to work depending on the inner
return type.
Actually I think this can work because of a Tnull (internal
compiler type) inference which can always implictly be converted
to the static return type (A or B, or even int*):
auto alwaysReturnNull()// `auto` is translated to Tnull by
inference because of `return null`
then:
A testA()
{
return alwaysReturnNull(); // Tnull can be implictly
converted to A
}
still nice tho.
