https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77505
Bug ID: 77505
Summary: Negative character length not treated as LEN=0
Product: gcc
Version: 5.4.0
Status: UNCONFIRMED
Severity: minor
Priority: P3
Component: fortran
Assignee: unassigned at gcc dot gnu.org
Reporter: urbanjost at comcast dot net
Target Milestone: ---
From section 4.4.5.2-5 of the f2008 standard, I think negative character
lengths
should be treated as LEN=0. In the following sample, if I enter a negative
value
the code gets a segmentation fault using gfortran 5.4.0 on Cygwin, at least.
program rabbithole
! 4.4.5.2-5 If the character length parameter value evaluates to a negative
value, the length of character entities declared is zero.
implicit none
character(len=:),allocatable :: text_block(:)
integer :: i
integer :: ii
character(len=10) :: cten='abcdefghij'
character(len=20) :: ctwenty='abcdefghijabcdefghij'
write(*,*)'DOES A NEGATIVE VALUE ACT LIKE LEN=0? (4.4.5.2-5)'
write(*,*)'ENTER NEGATIVE LENGTH ' ! enter a negative number to be mean
read(*,*)ii
text_block=[ character(len=ii) :: cten, ctwenty ]
write(*,*)'WRITE IT'
write(*,'(a)')(trim(text_block(i)),i=1,size(text_block))
end program rabbithole
Program received signal SIGSEGV: Segmentation fault - invalid memory reference.
Backtrace for this error:
#0 0xFFFFFFFFFFFFFFFF
#1 0xFFFFFFFFFFFFFFFF
#2 0xFFFFFFFFFFFFFFFF
#3 0xFFFFFFFFFFFFFFFF
#4 0xFFFFFFFFFFFFFFFF
#5 0xFFFFFFFFFFFFFFFF
#6 0xFFFFFFFFFFFFFFFF
#7 0xFFFFFFFFFFFFFFFF
#8 0xFFFFFFFFFFFFFFFF
#9 0xFFFFFFFFFFFFFFFF
#10 0xFFFFFFFFFFFFFFFF
#11 0xFFFFFFFFFFFFFFFF
#12 0xFFFFFFFFFFFFFFFF
#13 0xFFFFFFFFFFFFFFFF
/home/urbanjs/.twm/scripts_daily/quiet: line 8: 23784 Segmentation fault
(core dumped) $COMMAND
CYGWIN_NT-10.0 buzz 2.6.0(0.304/5/3) 2016-08-31 14:32 x86_64 Cygwin
GNU Fortran (GCC) 5.4.0
Copyright (C) 2015 Free Software Foundation, Inc.
