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