Is the following code valid?

[Dominique Dhumieres]

Is the following code:

MODULE debug
  LOGICAL debug_area
  NAMELIST/debugging/debug_area
END MODULE debug

PROGRAM ding
  USE debug
  IMPLICIT NONE
  NAMELIST/debugging/debug_area
  INTEGER :: ios
  OPEN(unit=10, status='unknown', file='input.dat')
  READ(unit=10, nml=debugging,  iostat=ios)
  PRINT*, 'nml=debugging',ios
END PROGRAM ding

valid? Gfortran and Portland group Fortran accept it
while xlf, ifort, and g95 reject it with (ifort):

fortcom: Error: namelist13.f90, line 9: The attributes of this name conflict with those made accessible by a USE statement.   [DEBUGGING]
  NAMELIST/debugging/debug_area
-----------^

Is this another example of invalid code for which a compiler
is allowed to do what ever it wants or is this a missed constraint?

TIA

Dominique