DP3: update patch for proper requirement of Python 3

Can upstream be convinced to just use FindPython3? The other
notable change in the patch is the removal of redundant
Python searches in deeper level CMakeLists.

Note: Build currently broken because of Casacore API, apparently.

DP3-buildfix.patch

@@ -35,7 +35,7 @@ index e4689f7..9068fdd 100644
    endforeach(_comp ${_find_components})
  endif(NOT CASACORE_INCLUDE_DIR)
 diff --git a/CMake/PythonInstall.cmake b/CMake/PythonInstall.cmake
-index 173f995..c15bbab 100644
+index 173f995..a1357c7 100644
 --- a/CMake/PythonInstall.cmake
 +++ b/CMake/PythonInstall.cmake
 @@ -24,10 +24,11 @@
@@ -48,7 +48,7 @@ index 173f995..c15bbab 100644
  
  # Derive the Python site-packages installation directory and build directory.
 -if(PYTHON_EXECUTABLE)
-+if(Python_EXECUTABLE)
++if(Python3_EXECUTABLE)
    set(_cmd
      "from distutils.sysconfig import get_python_lib"
      "from os.path import join"
@@ -57,7 +57,7 @@ index 173f995..c15bbab 100644
    )
    execute_process(
 -    COMMAND "${PYTHON_EXECUTABLE}" "-c" "${_cmd}"
-+    COMMAND "${Python_EXECUTABLE}" "-c" "${_cmd}"
++    COMMAND "${Python3_EXECUTABLE}" "-c" "${_cmd}"
      OUTPUT_VARIABLE _pydir
      ERROR_VARIABLE _pyerr
      OUTPUT_STRIP_TRAILING_WHITESPACE)
@@ -66,7 +66,7 @@ index 173f995..c15bbab 100644
      message(STATUS "Installation directory for Python extensions: ${PYTHON_INSTALL_DIR}")
    endif()
 -endif(PYTHON_EXECUTABLE)
-+endif(Python_EXECUTABLE)
++endif(Python3_EXECUTABLE)
  
  
  #
@@ -75,93 +75,57 @@ index 173f995..c15bbab 100644
  
    # Precondition check.
 -  if(NOT PYTHON_EXECUTABLE)
-+  if(NOT Python_EXECUTABLE)
++  if(NOT Python3_EXECUTABLE)
      message(FATAL_ERROR "python_install: Python interpreter not available")
 -  endif(NOT PYTHON_EXECUTABLE)
-+  endif(NOT Python_EXECUTABLE)
++  endif(NOT Python3_EXECUTABLE)
  
    # Parse arguments.
    # apart from the python files list, there are two additional arguments
 diff --git a/CMakeLists.txt b/CMakeLists.txt
-index 515aae1..671419d 100644
+index 0ae97ae..73327a8 100644
 --- a/CMakeLists.txt
 +++ b/CMakeLists.txt
-@@ -44,10 +44,40 @@ endif(IDGAPI_LIBRARIES AND IDGAPI_INCLUDE_DIRS)
+@@ -44,13 +44,12 @@ endif(IDGAPI_LIBRARIES AND IDGAPI_INCLUDE_DIRS)
  
  find_package(CFITSIO REQUIRED)
  
--#Prevent accidentally finding old BoostConfig.cmake file from casapy
-+# An attempt at common logic for Python and Boost:
-+# 0. Try CMake 3.12's FindPython, fall back to FindPythonInterp/Libs.
-+# 1. Use a default Python being found (environment should provide that).
-+# 2. Use that Python's version to look for modern versioned Boost pythonXY
-+#    component.
-+# 3. If that fails, resort to unversioned Boost python.
-+# Baseline for this is CMake 3.5, being available in LTS distros.
-+# We could require Boost >= 1.67 and CMake >= 3.12 and get rid
-+# of the fallbacks.
-+
-+find_package(Python COMPONENTS Interpreter Development)
-+if(NOT Python_FOUND)
-+  message(STATUS "Falling back to deprecated Python search.")
-+  find_package(PythonInterp REQUIRED)
-+  find_package(PythonLibs REQUIRED)
-+  set(Python_VERSION ${PYTHON_VERSION_STRING})
-+  set(Python_VERSION_MAJOR ${PYTHON_VERSION_MAJOR})
-+  set(Python_VERSION_MINOR ${PYTHON_VERSION_MINOR})
-+  set(Python_LIBRARIES ${PYTHON_LIBRARIES})
-+  set(Python_INCLUDE_DIRS ${PYTHON_INCLUDE_DIRS})
-+endif()
-+
+-find_package(PythonLibs 3 REQUIRED)
+-find_package(PythonInterp REQUIRED)
+-message(STATUS "Using python version ${PYTHON_VERSION_STRING}")
++find_package(Python3 COMPONENTS Interpreter Development)
++message(STATUS "Using python version ${Python3_VERSION}")
+ 
+ #Prevent accidentally finding old BoostConfig.cmake file from casapy
  set(Boost_NO_BOOST_CMAKE ON)
--find_package(Boost COMPONENTS date_time filesystem python3 program_options system unit_test_framework REQUIRED)
-+set(boostcomp date_time filesystem program_options system unit_test_framework)
-+set(boostpy ${Python_VERSION_MAJOR}${Python_VERSION_MINOR})
-+find_package(Boost 1.67.0 COMPONENTS ${boostcomp} python${boostpy})
-+if(NOT Boost_FOUND)
-+  message(STATUS "Falling back to old Boost search.")
-+  set(boostpy "")
-+  find_package(Boost REQUIRED COMPONENTS ${boostcomp} python${boostpy})
-+endif()
-+
+-set(BOOSTPY ${PYTHON_VERSION_MAJOR}${PYTHON_VERSION_MINOR})
++set(BOOSTPY ${Python3_VERSION_MAJOR}${Python3_VERSION_MINOR})
+ find_package(Boost COMPONENTS date_time filesystem python${BOOSTPY} numpy${BOOSTPY} program_options system unit_test_framework REQUIRED)
  include_directories(${Boost_INCLUDE_DIR})
-+include_directories(${Python_INCLUDE_DIRS})
  
- find_path(LOFAR_STATION_RESPONSE_DIR NAMES StationResponse/Station.h)
- find_library(LOFAR_STATION_RESPONSE_LIB stationresponse)
-@@ -165,8 +195,6 @@ set(DPPP_OBJECT $<TARGET_OBJECTS:DPPP_OBJ>)
- #
- # Dependencies of AOFlagger
- #
--find_package(PythonLibs 3 REQUIRED)
--find_package(PythonInterp REQUIRED)
- find_package(LibXml2 REQUIRED)
- find_package(PNG REQUIRED)
- find_library(FFTW3_LIB fftw3 REQUIRED)
-@@ -193,9 +221,9 @@ set(AOFLAGGERSTEP_OBJECT $<TARGET_OBJECTS:AOFlaggerStep_OBJ>)
- set(EXTRA_LIBRARIES ${EXTRA_LIBRARIES}
-   ${AOFLAGGER_LIB}
+@@ -198,7 +197,7 @@ set(EXTRA_LIBRARIES ${EXTRA_LIBRARIES}
    ${CASACORE_LIBRARIES}
--  ${Boost_DATE_TIME_LIBRARY} ${Boost_FILESYSTEM_LIBRARY} ${Boost_SYSTEM_LIBRARY}  ${Boost_PROGRAM_OPTIONS_LIBRARY} ${Boost_PYTHON3_LIBRARY}
-+  Boost::date_time Boost::filesystem Boost::system Boost::program_options Boost::python${boostpy}
+   ${Boost_LIBRARIES}
    ${EXTRA_LIBRARIES}
 -  ${PYTHON_LIBRARIES}
-+  ${Python_LIBRARIES}
++  ${Python3_LIBRARIES}
    ${IDGAPI_LIBRARIES}
    Threads::Threads)
    
 diff --git a/PythonDPPP/CMakeLists.txt b/PythonDPPP/CMakeLists.txt
-index 9194dc7..c8284a8 100644
+index 9194dc7..afd8545 100644
 --- a/PythonDPPP/CMakeLists.txt
 +++ b/PythonDPPP/CMakeLists.txt
-@@ -1,5 +1,5 @@
+@@ -1,5 +1,7 @@
  # If Boost-Python3 found, build this package. Otherwise give a warning.
 -if(${Boost_PYTHON3_FOUND})
-+if(${Boost_PYTHON${boostpy}_FOUND})
++#if(${Boost_PYTHON${boostpy}_FOUND})
++# We set Boost-python as reuired in toplevel build file.
++if(TRUE)
  
    include(PythonInstall)
  
-@@ -25,15 +25,6 @@ if(${Boost_PYTHON3_FOUND})
+@@ -25,16 +27,7 @@ if(${Boost_PYTHON3_FOUND})
    # Install Python modules
    python_install(__init__.py DESTINATION lofar/pythondppp)
  
@@ -175,5 +139,8 @@ index 9194dc7..c8284a8 100644
 -  include_directories(${Boost_INCLUDE_DIR})
 -
  #  add_subdirectory(test)
- else()
-   message (WARNING, " Boost-Python not found; PythonDPPP will not be built.")
+-else()
+-  message (WARNING, " Boost-Python not found; PythonDPPP will not be built.")
++#else()
++#  message (WARNING, " Boost-Python not found; PythonDPPP will not be built.")
+ endif()