Allocatable character strings in namelists?

[OP1]

Assume I have a text file called 'text.txt' which contains:

&A
S = 'Hi!'
/

The following code produces different output depending on which line is commented out for the definition of S. I thought allocatable characters were accepted in namelist groups?

PROGRAM P
IMPLICIT NONE
!CHARACTER(LEN=50) :: S
CHARACTER(LEN=:),ALLOCATABLE :: S
NAMELIST /A/ S
OPEN(UNIT=10,FILE='test.txt')
READ(10,NML=A)
WRITE(*,*) S
END PROGRAM P

[IanH]

The things in a namelist group need to be allocated ahead of executing any read or write statements for that namelist group.
 

[Steven_L_Intel1]

Yes, indeed. The standard theoretically could have specified automatic (re)allocation for allocatable, deferred-length character variables in a list-directed or NAMELIST READ, but didn't. 

[OP1]

Thanks for these answers. Too bad indeed these small features didn't make it to the standard - they could have been convenient.

[Steven_L_Intel1]

The topic has come up in the standards committee, but didn't generate much enthusiasm.