CHKSYS - Fortran 90/95
----------------------

(January 2004, Arjen Markus - arjen dot markus at wldelft dot nl)

This collection of programs written in Fortran 90/95
is intended to provide insight in the properties of
the language and the capabilities of the compilers.

The programs can be divided in two categories:
Those that can be compiled and those that should
cause error messages from the compiler.

In the latter category we have:

chkfunc.f90  - "obvious" errors regarding function calls
               (wrong interfaces etc.)

chkname.f90  - mistakes that are related to variables and their
               scope/name

chkarray.f90 - mistakes related to array handling (passing arrays
               to subroutines without an explicit interface for
               instance)

Unfortunately, not all compilers will find these mistakes.
The source code contains a description of the problems and an
indication where they are found in the source code (the comment
lines that start with !PROBLEM).

The programs that do run are:

chkformt.f90 - Checks the treatment of floating-point numbers
               in formats

chkstar.f90  - Shows the properties of list-directed input
               (READ( lu, *)) for a particular OS/compiler
               - some are compiler-specific!

test_genstruct.f90 - Demonstration of a method for storing
               of various types (via the function TRANSFER())

The last program may require some explanation:
Fortran 90/95 does not have a generic data type. So it would
seem that storing a real array and a derived type in one
general structure is impossible, unless you make a general
structure that has "slots" for all types that are to be
stored, like:

type ALL_DATA_TYPES_STORE
   integer, dimension(:), pointer       :: int_array
   real,    dimension(:), pointer       :: real_array
   type(MYDATA), dimension(:), pointer  :: mydata_array
   ...
end type

The program test_genstruct.f90 shows that this is not
necessary at all.


Programs that need still to be written:

- Program to check the behaviour with various types of files
  (notably line-endings and direct access files)
- Program that causes runtime errors (such as array bound violations,
  with the proper compiler flags, these errors must be detected)
- Program to check for a possible timestamp in module intermediate
  files - important to know this for the prevention of the so-called
  compilation cascade.
- Possibly others