http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57843
janus at gcc dot gnu.org changed:
What |Removed |Added
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CC| |janus at gcc dot gnu.org
--- Comment #2 from janus at gcc dot gnu.org ---
(In reply to John from comment #0)
> The code below does not do what's expected when compiled with gfortran-4.9
> (i.e., to print "this is right" instead of "what am I doing here?" every
> time the polymorphic assignment is invoked, and also printing the assigned
> values at the end, instead of the default ones.
>
> Maybe I still don't understand the semantics behind Fortran 2003+'s
> type-bound assignment (so I apologize in advance if this is not a bug), but
> it seems to me that the assign_itemType procedure is being used for
> assignment, even though it doesn't satisfy the requirement of exact type for
> the "right" argument ---is polymorphism being resolved at compile time even
> for dynamic cases?
Well, what is resolved at compile time is the generic assignment (in the same
sense as any generic procedure is resolved to a matching specific procedure at
compile time, be it type-bound or not). Therefore I would say that the output
of your code is correct according to the Fortran 2003 standard, and just your
expectations are a bit off ;)
I tried to cook the test case down a bit, in order to make it a bit easier to
understand:
module mod1
implicit none
type :: itemType
contains
procedure :: assign_itemType
generic :: assignment(=) => assign_itemType
end type
contains
subroutine assign_itemType(left, right)
class(itemType), intent(OUT) :: left
type(itemType), intent(IN) :: right
print *, 'what am I doing here?'
end subroutine
end module
module mod2
use mod1
implicit none
type, extends(itemType) :: myItem
character(3) :: name = ''
contains
procedure :: assign_myItem
generic :: assignment(=) => assign_myItem
end type
contains
subroutine assign_myItem(left, right)
class(myItem), intent(OUT) :: left
type(myItem), intent(IN) :: right
print *, 'this is right'
left%name = right%name
end subroutine
end module
program test_assign
use mod2
implicit none
integer :: i, j, n
class(itemType), allocatable :: table(:), item, aux(:)
! process
do i = 1, 2
print '(/,"item ",I0)', i
call setItem('abc', item)
if (ALLOCATED(table)) then
n = SIZE(table)
call MOVE_ALLOC(table, aux)
allocate (table(n+1), MOLD = item)
print *, 'table is same type as aux?:', SAME_TYPE_AS(table, aux)
do j = 1, n
table(j) = aux(j)
enddo
table(n+1) = item
else
allocate (table(1), SOURCE = item)
endif
print *, 'table is same type as item?:', SAME_TYPE_AS(table, item)
print *, 'table is same type as itemType?:', SAME_TYPE_AS(table,
itemType()) !*****
print *, 'table extends type itemType?:', EXTENDS_TYPE_OF(table,
itemType())
enddo
! output
do i = 1, SIZE(table)
select type (item => table(i))
type is (myItem)
print *, i, item%name
end select
enddo
contains
subroutine setItem(name, item)
character(*), intent(IN) :: name
class(itemType), allocatable, intent(OUT) :: item
allocate (myItem :: item)
select type (item)
type is (myItem)
print *, 'setting...'
item%name = name
end select
end subroutine
end
I get the same (supposedly correct) output with 4.8 and trunk:
item 1
setting...
table is same type as item?: T
table is same type as itemType?: F
table extends type itemType?: T
item 2
setting...
table is same type as aux?: T
what am I doing here?
what am I doing here?
table is same type as item?: T
table is same type as itemType?: F
table extends type itemType?: T
1
2
while 4.7 gives a runtime error:
item 1
setting...
table is same type as item?: T
table is same type as itemType?: F
table extends type itemType?: T
item 2
At line 80 of file test_assign.f90
Fortran runtime error: Attempting to allocate already allocated variable 'item'
