[J3] [EXTERNAL] [BULK] Can SOURCE and PAD argument of intrinsic RESHAPE have different declare type but the same dynamic type?

[Clune, Thomas L. (GSFC-6101)]

Hi Daniel,

In your case the compiler could in theory “figure out” that b1 is of the same type as c1.   But consider if b1 were instead a CLASS(Base) dummy argument.     It might then have a different dynamic type, in which case it would not make sense as a PAD.    We want this to be caught at compile time rather than run time.


  *   Tom

From: J3 <j3-bounces at mailman.j3-fortran.org> on behalf of Daniel Chen via J3 <j3 at mailman.j3-fortran.org>
Date: Wednesday, January 29, 2025 at 12:16 PM
To: Van Snyder via J3 <j3 at mailman.j3-fortran.org>
Cc: Daniel Chen <cdchen at ca.ibm.com>
Subject: [EXTERNAL] [BULK] [J3] Can SOURCE and PAD argument of intrinsic RESHAPE have different declare type but the same dynamic type?
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Hello,

Consider the following code:
```
program main

    type Base

        integer   :: i = 88

    end type



    type, extends(Base) :: Child

        integer :: j = 99

    end type



    type(Child) :: c1(10)

    type(Child) :: c2(3,5)

    class(Base), allocatable :: b1(:)



    c1 = (/ (Child(i,i+100), i=1,10) /)

    allocate(Child::b1(2))



    c2 = reshape(c1, (/3,5/), b1, (/2,1/))   !! ERROR as c1 and b1 have different declare type.

end
```

The code is invalid as the standard requires the SOURCE and the PAD argument of intrinsic RESHAPE to have the same declare type and dynamic type. SOURCE=c1 has the declare type of Child, and PAD=b1 has the declare type of Base although they have the same dynamic type.

```
PAD (optional) shall be an array of the same type and type parameters as SOURCE.
```


It seems to me the code is not harmful. What is the reason that the standard requires both to have the same declare type?

Thanks in advance!

Daniel
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