Fortran: error #6562: A data initialization-expr is not valid for this object

Question

I am trying to initialize a local logical array in a Fortran subroutine to false, but I get the error:

error #6562: A data initialization-expr is not valid for this object.

Here is my declaration:

  integer                      , intent(in)    :: nLOW 
  integer                      , intent(in)    :: nUP
  logical , dimension(nLOW:nUP)                :: leastSQUARE =  .false.

I get the same error if I use:

  integer                                      :: I
  integer                      , intent(in)    :: nLOW 
  integer                      , intent(in)    :: nUP
  logical , dimension(nLOW:nUP)                :: leastSQUARE =  (/ (.false., I = nLOW:nUP) /)

If I write:

  integer                      , intent(in)    :: nLOW 
  integer                      , intent(in)    :: nUP
  logical , dimension(1:100)               :: leastSQUARE =   .false.

the subroutine compiles with zero errors. Any idea why this happens? I clearly need leastSQUARE with dimensions nLOW:nUP, so the latter is not a workaround.

Answer 1

I believe that the error-generating construction is forbidden by the language standard, specifically (in the Fortran 2008 version) by C506 on R503. That constraint states

An initialization shall not appear if object-name is a dummy argument, a function result, an object in a named common block unless the type declaration is in a block data program unit, an object in blank common, an allocatable variable, or an automatic object.

leastSQUARE is just such an automatic object, one whose bounds are only known at run-time. You'll have to initialise it separately from its declaration.

To be clear (thanks to @IanH), you will have to execute an assignment statement to give your automatic object an initial value. My use of the verb initialise in the previous paragraph was not Fortran standard standard.