https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90563
Bug ID: 90563
Summary: Out of bounds error when compiling with -Wextra
Product: gcc
Version: 8.3.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: fortran
Assignee: unassigned at gcc dot gnu.org
Reporter: m...@tobias-neumann.eu
Target Milestone: ---
The following program fails to compile with gfortran 8 and 9 (not with 7 and
below) when compiling with -Wextra. -Wextra is supposed to only enable
additional warnings, not enable new errors. I also can't see additional bounds
checks in the additional warnings that are enabled with extra:
https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html
% gfortran9 -Wextra -o test ./bcheck.f90
[14:20:23]
./bcheck.f90:11:28:
11 | p(j) = p(swap(j))
| 1
Error: Index in dimension 1 is out of bounds at (1)
./bcheck.f90:11:28:
9 | do j=1,6
| 2
10 | if (j<5) then
11 | p(j) = p(swap(j))
| 1
Warning: Array reference at (1) out of bounds (6 > 4) in loop beginning at (2)
[-Wdo-subscript]
Obviously the compiler is not clever enough to take into account the constraint
from the if, but I don't think this should throw an error with -Wextra.
program test
implicit none
integer, parameter :: swap(4) = [2,1,3,4]
real :: p(20)
integer :: j
p = 0.0
do j=1,6
if (j<5) then
p(j) = p(swap(j))
endif
enddo
end program
