Preprocessing options use non-standard naming conventions

[Yann Pouillon]

The preprocessing options used in LibGridXC follow non-standard naming conventions that may lead to name clashes in some cases, while some uses may be improper and/or obsolete.

The options in version 0.7.3 are the following: DEBUG_XC, GRID_SP, LIBXC, MPI, OLD_CRAY, __TEST__MODULE__ALLOC__.

This can be solved by:
  - renaming LIBXC to HAVE_LIBXC;
  - renaming MPI to HAVE_MPI;
  - possibly getting rid of the OLD_CRAY option;
  - refactor the __TEST__MODULE__ALLOC__ feature to have it handled as a test by the build system.

Part of this issue will be fixed at the same time as bug #1714246.

[Yann Pouillon (pouillon)]

A few words to clarify the proposed refactoring.

The undocumented __TEST__MODULE__ALLOC__ CPP option is associated to the optional compilation of a test program located in the src/alloc.F90 source file. This practice is strongly discouraged, because:

  - it hides tests which may be of importance deeply into the source code;
  - it allows parts of the source to be kept unmaintained for long periods of times.

The recommended practice is instead to provide the test program in a separate file and control its compilation from a Makefile, in addition to briefly documenting its purpose.

[Alberto Garcia (albertog)]

My goal with the 'preprocess-to-enable' test in alloc.F90 was to have a self-contained file that could be shipped around without turning it into a new library. Note that it has no other dependencies.

Can you leave as it is but include a test in your build system to exercise the self-contained code?

[Alberto Garcia (albertog)]

In Siesta we are currently using the convention (for new features) to have preprocessor names of the form SIESTA__XXXXX.
Nick suggested it to avoid possible clashes when a cascade of programs and libraries is compiled. I guess that you have this under control.