Hi,
I've encountered a "feature" in the SGI MipsPro F90
compiler and would like to know what other compilers
make of this, and whether the behaviour of the SGI
compiler conforms to the standard.
Attached find a short test program that tests the
behaviour of a variable initialized at declaration time,
vs. one initialized in a separate statement (itest1 and
itest2 respectively). The variable that's initialized
at declaration time behaves exactly like a "saved"
variable even though there's no save statement in the code.
Is this expected behaviour? It seems counter-intuitive
to me. I've spent the last two weeks tracking this
one down, looking for a non-existent memory stomp. Grrrr.
A colleague of mine found the following statement in
the SGI documentation which clearly points out this
feature so it's not a bug per se. I don't find this
behaviour obvious though.
"Initialization of a variable in a type declaration
statement or any part of a variable in a DATA statement
implies that the variable has the SAVE attribute unless
the variable is in a named common block."
Test Code:
SUBROUTINE SUB1(INDX)
IMPLICIT NONE
INTEGER, INTENT(IN) :: INDX
LOGICAL :: ITEST1 = .TRUE.
LOGICAL :: ITEST2
itest2 = .true.
if (mod(indx,5) == 0) then
itest1 = .false.
itest2 = .false.
endif
write(*,'(a,i,l,l)') 'indx, itest1, itest2 = ',indx,itest1,itest2
RETURN
END SUBROUTINE SUB1
PROGRAM TEST
INTEGER :: INDX
do indx = 1,10
call sub1(indx)
end do
STOP
END PROGRAM
Test Output:
indx, itest1, itest2 = 1 T T
indx, itest1, itest2 = 2 T T
indx, itest1, itest2 = 3 T T
indx, itest1, itest2 = 4 T T
indx, itest1, itest2 = 5 F F
indx, itest1, itest2 = 6 F T
indx, itest1, itest2 = 7 F T
indx, itest1, itest2 = 8 F T
indx, itest1, itest2 = 9 F T
indx, itest1, itest2 = 10 F F
Thanks for any enlightenment,
Catherine
--
-------------------------------------------------------------------------
Catherine Moroney phone : (818) 393-3392
Jet Propulsion Laboratory fax : (818) 393-3134
MailStop 168-414 email : [log in to unmask]
4800 Oak Grove Drive
Pasadena, CA 91109-8099
