https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126381
Bug ID: 126381
Summary: Nullifying a deferred-length character pointer in a
derived-type argument causes segmentation fault
Product: gcc
Version: 16.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: fortran
Assignee: unassigned at gcc dot gnu.org
Reporter: mpahlow at geomar dot de
Target Milestone: ---
The system type is macos tahoe 26.5.2 with CommandLineTools version
26.6.0.0.1781586589
gcc-16.1.0 was installed with brew
The following code produces the segmentation fault:
!file test.f90
MODULE mymodule
IMPLICIT NONE
INTEGER, PARAMETER :: dp=KIND(0D0)
TYPE :: dimension
CHARACTER(LEN=:), POINTER :: char_vals(:)
END TYPE dimension
CONTAINS
SUBROUTINE values_and_bounds (dimns)
IMPLICIT NONE
! TYPE(dimension), TARGET, INTENT(INOUT) :: dimns ! works
CLASS(dimension), TARGET, INTENT(INOUT) :: dimns ! crashes
write(*,*)'values_and_bounds: ','x'
NULLIFY (dimns%char_vals)
write(*,*)'values_and_bounds: ','y'
END SUBROUTINE values_and_bounds
END MODULE mymodule
PROGRAM test
USE mymodule
IMPLICIT NONE
TYPE(dimension) :: dimen
NULLIFY (dimen%char_vals)
write(*,*)'a'
CALL values_and_bounds(dimns=dimen)
WRITE(*,*)'b'
END PROGRAM test
! end of file test.f90
Command line:
gfortran -Og -Wall -Wextra -fno-strict-aliasing -fwrapv
-fno-aggressive-loop-optimizations -fsanitize=address,undefined -o test
test.f90; ./test
There is no output from the compiler but executing the executable shows:
a
values_and_bounds: x
test.f90:13:29: runtime error: member access within null pointer of type
'struct dimension'
Program received signal SIGSEGV: Segmentation fault - invalid memory reference.
Backtrace for this error:
#0 0x10446b323
#1 0x10446a063
#2 0x18dc63743
#3 0x10423ce67
#4 0x10423d0cf
#5 0x10423d24f
Replacing "CLASS(dimension)" with "TYPE(dimension)" works.
Compiling with gfortran version 15.3.0 with the above command line makes the
executable hang but compiling with
gfortran-15 -Og -Wall -Wextra -fno-strict-aliasing -fwrapv
-fno-aggressive-loop-optimizations -o test test.f90; ./test
works
