https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109157
Bug ID: 109157
Summary: -fbound-check: false positive
Product: gcc
Version: 12.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: fortran
Assignee: unassigned at gcc dot gnu.org
Reporter: philippe.wautelet at aero dot obs-mip.fr
Target Milestone: ---
Hello,
The following code triggers a wrong out of bound detection:
> cat ndimlist.f90
program ndimlistbug
implicit none
integer, parameter :: FIELDSIZE=5
type :: tfieldmetadata_base
integer, dimension(10) :: ndimlist = -2
end type tfieldmetadata_base
type(tfieldmetadata_base), dimension(FIELDSIZE) :: tzfields
call write_diachro_lfi( tzfields )
contains
subroutine write_diachro_lfi( tpfields )
class(tfieldmetadata_base), dimension(:), intent(in) :: tpfields
print *,tpfields(1)%ndimlist
print *,tpfields(1)%ndimlist(8)
end subroutine write_diachro_lfi
end program ndimlistbug
If compiled with gfortran 12.2.0 (but also 11.1.0, 11.2.0, 11.3.0 and 12.1.0),
it gives:
> gfortran -g -fbounds-check ndimlist.f90
> ./a.out
-2 -2 -2 -2 -2 -2
-2 -2 -2 -2
At line 18 of file ndimlist.f90
Fortran runtime error: Index '8' of dimension 1 of array
'tpfields%_data%ndimlist' above upper bound of 5
Error termination. Backtrace:
#0 0x400aec in write_diachro_lfi
at /home/waup/F90/bug_gcc/ndimlist/ndimlist.f90:18
#1 0x4008ee in ndimlistbug
at /home/waup/F90/bug_gcc/ndimlist/ndimlist.f90:11
#2 0x400b8f in main
at /home/waup/F90/bug_gcc/ndimlist/ndimlist.f90:11
It seems there is a confusion between the size of tpfields and the size of
tpfields()%ndimlist. This can be seen if FIELDSIZE is set to at least the size
of ndimlist.
The bug is not present with versions of gfortran below 11.
