Bulletin number:  9
Products affected: D713D
Description: Failure to load BLOCK DATA in FORTRAN
Component: ilink
Date: Fri Feb 2 16:41:12 GMT 1990
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There is a bug in the version of ilink which was distributed with the
fortran compiler.  This was caused by a slight "improvement" which was
made to it.  It now loads the first module in the list (mainent)
unconditionally, and any others if they satisfy an open reference.
This is perfectly valid for almost all languages. Except FORTRAN.  A
BLOCK DATA subprogram has no references to it.

The afserver version works because it loads everything.

The following three files are those I have used to verify the problem.
The PRINT statement should print out the value '123'.  Instead it
prints out a value over 2 million.


File: hello1.bat
t4f hello1a
t4f hello1b
ilink mainent.c4x hello1a.bin hello1b.bin frtl.lib /o hello1.c4x
iboot hello1.c4x
iserver /sb hello1.b4x

File: hello1a.f77
      PROGRAM HELLO
      COMMON /ABC/ IJK
      PRINT *,'Hello, world ', IJK
      END

File: hello1b.f77
       BLOCK DATA
       COMMON /ABC/ IJK
       DATA IJK / 123 /
       END


There is a workaround.  A dummy entry point must be defined in the
same source file as the BLOCK DATA subprogram.  This should be called
from somewhere within the program, exactly where is not important.

Because is an unresolved reference the entire module containing both
DUMMY and BLOCK DATA are read in by the linker.  Thus end of problem.

File: hello2a.f77
      PROGRAM HELLO
      COMMON /ABC/ IJK
      PRINT *,'Hello, world ', IJK
      CALL DUMMY()
      END

File: hello2b.f77
      SUBROUTINE DUMMY()
      END
      BLOCK DATA
      COMMON /ABC/ IJK
      DATA IJK / 123 /
      END


This could be very nasty if programs have not been fully tested.
Please pass this information on to everyone programming in this
version of fortran.