https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99765
Bug ID: 99765
Summary: Explicit dimension size declaration of pointer array
allowed
Product: gcc
Version: 4.8.4
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: fortran
Assignee: unassigned at gcc dot gnu.org
Reporter: nickpapior at gmail dot com
Target Milestone: ---
A mishandling of variable declarations
Consider this program:
program test
real, dimension(10), pointer :: a(:) => null()
print *, associated(a)
allocate(a(2))
print *, size(a)
!print *, size(a(1)) ! obviously fails as a(1) is a scalar
end program test
It is ambiguous to determine the size of a. The programmer may think that after
allocation one has 2x10 elements a(1:2)(1:10) however what is happening is that
the dimension(10) attribute is completely ignored.
I can't find anywhere in the standard mentioning that this way of definition is
wrong, but I think it clearly shouldn't be allowed.
I.e. it is unclear whether the user wants a(1:2)(1:10) or a(1:10)(1:2), in any
case neither of the results are achieved.
I found this bug in 4.8.4 and also in 9.3.0, so I assume it exists in all in
between.
A few more cases that resemble this:
real, dimension(10), allocatable :: a(:)
behaves exactly like with pointers. It is not well-defined and gets to the
a(1:2) case.
real, dimension(10), allocatable :: a(10)
rightfully errors out on compilation with a somewhat unclear error message
3 | real, dimension(10) :: a(10)
| 1
Error: Symbol ‘a’ at (1) already has basic type of REAL
