add_dune_test: Handle complex expressions in `CMAKE_GUARD`

The check if(NOT ${condition}) does not behave as expected when condition is a complex string expression such as A OR B. It does however work when condition is a list.

Therefore convert condition to a list by calling separate_arguments.

Note that this change also adds missing parenthesis around condition which also results in wrong results for complex expressions.

Closes issue #39 (closed).

What's about more complex conditions like (HAVE_ALUGRID OR HAVE_UGGRID) AND (HAVE_SUPERLU OR HAVE_UMFPACK)? That's not a trick question, but a real problem. I know it does not work currently, but while we are trying to fix this code…

@gruenich They seem to work if you write "( A OR B ) AND ( C OR D )" with spaces around the parenthesis, see the example CMake script below (run with cmake -P ${foo}). I don't know enough about CMake to explain why it is so strange.

foreach(A 0 1)
  foreach(B 0 1)
    foreach(C 0 1)
      foreach(D 0 1)

        #message("A=${A} B=${B} C=${C} D=${D}")

        if(NOT ((A OR B) AND (C OR D)))
          message(true)
        else()
          message(false)
        endif()

        set(X "( A OR B ) AND ( C OR D )")
        # No spaces leads to unhappiness:
        #set(X "(A OR B) AND (C OR D)")
        separate_arguments(X)
        #message("X=${X}")
        if(NOT (${X}))
          message(true)
        else()
          message(false)
        endif()

        message(======)
      endforeach()
    endforeach()
  endforeach()
endforeach()

Added 1 commit:

• 074f0993 - [cmake] Mention complex expression for CMAKE_GUARD in documentation

Status changed to merged

mentioned in commit 3d6dc19c

Might be a string vs. list issue. During processing the string might be converted to a list. "( A OR B ) AND ( C OR D )" becomes (;A;OR;B;);AND;(;C;OR;D;). Without spaces this conversion would not make sense because of "(A", etc. in there.

Sorry I did not reply to this, I was away for some days. Thanks @ansgar for fixing the mess I created there (although I will absolutely blame CMake's policy of handling lists...) The fix looks good, I did not know that separate_arguments existed.

Mentioned in commit 3d6dc19c