Programming

Hello.
I'm looking for a quite "interesting" bug I'm using fortran 90, compiler gfortran and the main idea is for every time step I build a bin structure for search contact between particles, for this at the begining

Code:

TYPE :: circle_index
			INTEGER(kind = 4) :: ind_p
			TYPE(circle_index), POINTER :: p
END TYPE
		
TYPE(circle_index), DIMENSION(:), POINTER :: Bins(:)
TYPE(circle_index), DIMENSION(:), POINTER :: Bins_Tail(:)
TYPE(circle_index),POINTER :: headB

And the next part it's called almost every time step.
I compute rows and colums variables for allocate memory

Code:

ALLOCATE(Bins(rows*columns),Bins_Tail(rows*columns))

Then I do the search for finally

Code:

DO pos = 1, rows*columns
	headB => Bins(pos)%p
	DO
		IF(.NOT. ASSOCIATED(headB)) EXIT
		ptr_index => headB%p
		DEALLOCATE(headB)
		headB => ptr_index
	END DO
END DO
DEALLOCATE(Bins, Bins_Tail)

The search is ok, but I get some of these errors
*** glibc detected *** double free or corruption (out)
*** glibc detected *** free(): invalid next size (normal)

And it's wierd for me because if I'm deallocating in the wrong way I expect the error at the beginig but it does not. The error just appear more after, am I doing it wrong?
I already use -fbounds-check but does not work and is really dificult debug step by step because the simulation is very long, so any ideas?

Does anybody have an idea what is happening here? Have you seen something similar yet? What could i still try?

Greetings & thank you,
Marce.

Not deeply understanding this, but DEALLOCATE( headB ) has no corresponding ALLOCATE() . . . . You put Bins in headB, so are you double DEALLOCATING it? Maybe you need a soft delete flag in your row or make a new array with the deletes not added, or allocate and deallocate row by row.