Dear Paul,
Paul Richard Thomas wrote:
> c = [ a, b ]
Is exactly the abomination that I did not want to exist! What happens
if 'a' and 'b' have different dynamic types?
Actually, I start to get lost in the fine prints. One finds:
"The dynamic type of an array constructor is the same as its declared type."
That means that for "[a, b]" one has as constructor type the declared
type of each ac-value, which has to be the same. Thus, one has declared
type of "a" equals dynamic type of "a" - and the same for "b" with "a"
and "b" having the same type.
The question gets more interesting with:
[ t2 :: a, b]
Here, "a" and "b" need to be of declared type "t2" or of one extension
of it - and can have any dynamic type. But due to the "t2" only
components which are also in "t2" matter.
See also PR 51864
> That's accepted by the Cray compiler (7.1.4.111) and produces:
> 5 5 5 5 5 5 5 5
Which is the expected and valid result.
> Though, if one changes "t ::" to "t2 ::", the result is the slightly
> surprising
> 5 5 6 6 5 5 5 5
> 6 5 5 5 6 6 6 6
That code is actually invalid. Either both need to be of type "t" or one
needs to a type spec and - for "[ t2 :: a, b]" also a different declared
type.
> I think that code is valid Fortran 2003/2008. But to cheer you up: Unlimited
> polymorphic expressions are not allowed in array constructors (cf. C4107).
Surely it cannot be valid?
"C4106 (R472) An ac-value shall not be unlimited polymorphic."
The reason is probably that class(*) is type compatible with everything
thus this loophole had to be closed.
PS I know how to fix PR51634.... will get on to it as soon as I have a moment.
Great!
Tobias
