Failure to detect undefined variable in a common block

In the following program, one of the variables in a COMMON block is used before it has been defined.

!
      program buggy
      implicit none
      external blkd
      integer i,j,k,l,m,n
      common /bb/i,j,k,l,m,n
      integer ksum
      ksum = i+j+k+l+m+n
      print *,k,ksum
      end program
!
      block data blkd
      implicit none
      integer i,j,k,l,m,n
      common /bb/i,j,k,l,m,n
      data i,j,l,m,n/1,2,4,5,6/  !k is not defined
      end
!

Compiling with /undef in a 32-bit compilation yields an EXE that when run displays the error.

With /64 /undef, however, the error goes undetected.

mecej4

Thank you for the bug report which I have logged for investigation.

mecej4

It turns out that /UNDEF has not been implemented for BLOCK DATA and 64 bit programming. This was presumably because of the complexities of handling this for 64 bits and the understanding that BLOCK DATA is rarely used.

I have been informed that there are no immediate plans to implement this feature and I will change the documentation to reflect this.

Thanks, Paul. I understand that it can be difficult to support debugging code with old features, such as BLOCKDATA, for which modern alternatives are available.