cp2k/docs/development/error-handling.md

Error Handling

In CP2K there exist three convenient macros for error handling. They are defined in src/base/base_uses.f90, and are therefore always available. However, these macros can only be used for short messages (approximately less than 7 words), because of Fortran's line length limitation.

   CPWARN("A short warning message")
   CPABORT("A short error message")
   CPASSERT(2 > 1) ! For sanity checks only, not for user errors.

For longer messages one can use these two routines:

   CALL cp_warn(__LOCATION__,"A long warning message "//&
                "which can span multiple lines and contains "//&
                "some valuable advice for the user.")

   CALL cp_abort(__LOCATION__,"A long error message "//&
                 "with even more valuable advice.")      

Messages from `CPWARN` and `cp_warn` are only printed on the first MPI-rank.
Warnings issued on other ranks are ignored.

Cheat Sheet

If you want to...

• print a short warning message, then you should use: CPWARN("your short message")
• print a longer warning message, then you should use:

  CALL cp_warn(__LOCATION__,"your lengthy message, "//&
              "which can even span multiple lines")

• stop the program with a short error message, then you should use: CPABORT("your short message")
• stop the program with a longer error message, then you should use:

   CALL cp_abort(__LOCATION__,"your lengthy message, "//&
               "which can even span multiple lines")

• have a simple assertion without a custom error message, then you should use: CPASSERT(your_logical_expression)
• have a simple assertion with a short error message, then you should use:

IF(.NOT.your_logical_expression) CPABORT("your short message")

• have a complex assertion with a short error message, then you should use:

  IF(.NOT.your_super_complicated_logical_expression_that_takes_alot_of_space)&
    CPABORT("your short message")

• have a lengthy assertion with a longer error message, then you should use:

   IF(.NOT.your_super_long_logical_expression_that_takes_alot_of_space)&
      CALL cp_abort(__LOCATION__,"your lengthy message"//&
                    "which again can even span multiple lines")