[a.fixSWIGWrapperBuild_i891] Avoid unnecessary rebuilding of the SWIG wrappers (Closes #891)

Merging branch 'a.fixSWIGWrapperBuild_i891'  into 'main'.

* `SwigLib.cmake` is modified so that SWIG-produced wrappers be produced once (unless dependencies are updated).  
* All SWIG-related fragments are gathered into `SwigLib.cmake`.
* The dependencies of PyCore and Fit modules are corrected.
* Example Python-scripts are installed.

Closes issue #891

See merge request !2357

CMakeLists.txt

@@ -240,7 +240,6 @@ foreach(lib ${CoreComponents})
     add_subdirectory(${lib})
 endforeach()
 if(BORNAGAIN_PYTHON)
-    add_dependencies(BornAgainFit swig_runtime)
     if (CONFIGURE_EXAMPLES)
         add_subdirectory(rawEx)
     endif()

PyCore/CMakeLists.txt

@@ -4,7 +4,7 @@
 
 # NOTE: The module is directly dependent on Python and Numpy C-API
 if(NOT BORNAGAIN_PYTHON)
-    return()
+    message(FATAL_ERROR "PyCore module requested although BORNAGAIN_PYTHON=false")
 endif()
 
 set(component PyCore)
@@ -14,6 +14,7 @@ set(lib BornAgain${component})
 # Python-dependent source files
 file(GLOB_RECURSE source_files */*.cpp)
 file(GLOB_RECURSE include_files RELATIVE ${CMAKE_CURRENT_SOURCE_DIR} */*.h)
+list(APPEND include_files "${AUTO_WRAP_DIR}/swig_runtime.h")
 
 # --- define target properties ---
 add_library(${lib} SHARED)
@@ -24,6 +25,10 @@ set_target_properties(${lib} PROPERTIES
     INCLUDE_FILES "${include_files}"
     EMBED_PYTHON ${BORNAGAIN_PYTHON})
 
+if(CONFIGURE_BINDINGS)
+    add_dependencies(${lib} swig_runtime)
+endif(CONFIGURE_BINDINGS)
+
 # --- make the library ---
 MakeLib(${lib})
 

cmake/BornAgain/MakeLib.cmake

@@ -11,22 +11,6 @@ function(MakeLib lib)
 
     string(STRIP "${swigtmpdir}" swigtmpdir)
 
-    if(withPython AND swigtmpdir)
-
-        if((CLANG) OR (GCC))
-            # suppress warnings from auto-generated code (last updated for Swig 4.0.1)
-            set_source_files_properties(${AUTO_WRAP_DIR}/lib${lib}_wrap.cpp
-                PROPERTIES COMPILE_OPTIONS
-                "\
--Wno-unused-parameter;\
--Wno-missing-field-initializers;\
--Wno-sometimes-uninitialized;\
--Wno-deprecated-declarations")
-        endif()
-
-        list(APPEND source_files ${AUTO_WRAP_DIR}/lib${lib}_wrap.cpp)
-    endif()
-
     set_target_properties(${lib} PROPERTIES
         SOURCES "${source_files}"
         PREFIX ${libprefix}

cmake/multipython/PyDependences.cmake

@@ -63,3 +63,7 @@ if(BA_PY_PACKAGE)
         Py3_LIBRARY_DIRS "${Python3_LIBRARY_DIRS}"
         )
 endif()
+
+# install Python example scripts
+install(DIRECTORY ${EXAMPLES_PUBL_DIR}
+    DESTINATION ${destination_share} COMPONENT Examples FILES_MATCHING PATTERN *.py )

cmake/multipython/SwigLib.cmake

@@ -8,31 +8,11 @@ function(SwigLib name lib swigtmpdir)
         message(FATAL_ERROR "Function SwigLib called though BORNAGAIN_PYTHON=false")
     endif()
 
-    # configure SWIG runtime (only once)
-    if(NOT TARGET swig_runtime)
-        message(STATUS "SwigLib: configure SWIG runtime")
+    message(STATUS "SwigLib ${name}: ${lib} => ${swigtmpdir}")
 
-        if(CONFIGURE_BINDINGS)
-            add_custom_command(
-                OUTPUT ${AUTO_WRAP_DIR}/swig_runtime.h
-                COMMAND ${SWIG_EXECUTABLE} -c++;-python;-external-runtime;${AUTO_WRAP_DIR}/swig_runtime.h
-                DEPENDS ${swig_dependencies} ${include_files}
-            )
-        endif()
-
-        add_custom_target(swig_runtime DEPENDS ${AUTO_WRAP_DIR}/swig_runtime.h)
-
-        if(BA_CPP_API)
-            install(FILES ${AUTO_WRAP_DIR}/swig_runtime.h
-                DESTINATION ${destination_include}/Wrap COMPONENT Headers)
-        endif()
-    endif()
-
-    message(STATUS "SwigLib ${name}: ${lib} ${swigtmpdir}")
+    get_target_property(include_files ${lib} INCLUDE_FILES)
 
     if(CONFIGURE_BINDINGS)
-        file(MAKE_DIRECTORY ${swigtmpdir})
-
         # static (manually written) input files
         set(swig_dependencies
             ${SWIG_DIR}/lib${lib}.i
@@ -41,12 +21,28 @@ function(SwigLib name lib swigtmpdir)
             ${SWIG_DIR}/ignoreSample.i
         )
 
-        foreach(FNAM ${swig_dependencies})
-            if(NOT EXISTS ${FNAM})
-                message(FATAL_ERROR "Could NOT find SWIG input ${FNAM}")
+        foreach(fname ${swig_dependencies})
+            if(NOT EXISTS ${fname})
+                message(FATAL_ERROR "Could NOT find SWIG input ${fname}")
             endif()
         endforeach()
 
+        # configure SWIG runtime (only once)
+        # NOTE: PyCore module depends on SWIG runtime
+        if(NOT TARGET swig_runtime)
+            message(STATUS "SwigLib: configure SWIG runtime")
+
+            add_custom_command(
+                OUTPUT ${AUTO_WRAP_DIR}/swig_runtime.h
+                COMMAND ${SWIG_EXECUTABLE} -c++;-python;-external-runtime;${AUTO_WRAP_DIR}/swig_runtime.h
+                DEPENDS ${swig_dependencies} ${include_files}
+            )
+
+            add_custom_target(swig_runtime DEPENDS ${AUTO_WRAP_DIR}/swig_runtime.h)
+        endif()
+
+        file(MAKE_DIRECTORY ${swigtmpdir})
+
         # Run Swig.
         #     Please keep -Werror, in order not to overlook critical warnings.
         #     Dispensable warnings are disabled in Wrap/Swig/warnings.i.
@@ -55,8 +51,8 @@ function(SwigLib name lib swigtmpdir)
             ";-I${LibHeinz_INCLUDE_DIR}"
             ";-I${CMAKE_SOURCE_DIR};-I${CMAKE_BINARY_DIR}/inc")
 
-        add_custom_target(lib${lib}_py_wrappers ALL
-            BYPRODUCTS ${swigtmpdir}/lib${lib}.py
+        add_custom_command(
+            OUTPUT ${swigtmpdir}/lib${lib}.py
                    ${AUTO_WRAP_DIR}/lib${lib}_wrap.h
                    ${AUTO_WRAP_DIR}/lib${lib}_wrap.cpp
                    ${AUTO_WRAP_DIR}/lib${lib}.py
@@ -68,30 +64,53 @@ function(SwigLib name lib swigtmpdir)
                     ${AUTO_WRAP_DIR}/lib${lib}.py
             DEPENDS ${swig_dependencies} ${include_files}
             COMMENT "SWIG: build Python wrapper ${AUTO_WRAP_DIR}/lib${lib}.py"
-            )
+        )
 
         string(REPLACE ";" " " SWIG_FLAGS_STR "${SWIG_FLAGS}")
         set(SWIG_FLAGS_STR "${SWIG_FLAGS_STR}" CACHE INTERNAL "")
         set(SWIG_DIR "${SWIG_DIR}" CACHE INTERNAL "")
-    else()
-        # assumes that lib${lib}_wrap.h, lib${lib}_wrap.cpp and lib${lib}.py
-        # are already present in ${AUTO_WRAP_DIR}
-        add_custom_target(lib${lib}_py_wrappers ALL
-            DEPENDS ${AUTO_WRAP_DIR}/lib${lib}_wrap.h
-            ${AUTO_WRAP_DIR}/lib${lib}_wrap.cpp
-            ${AUTO_WRAP_DIR}/lib${lib}.py
-        )
     endif()
 
+    # assumes that lib${lib}_wrap.h, lib${lib}_wrap.cpp and lib${lib}.py
+    # are already present in ${AUTO_WRAP_DIR}
+    add_custom_target(lib${lib}_py_wrappers
+        DEPENDS
+        ${AUTO_WRAP_DIR}/lib${lib}_wrap.h
+        ${AUTO_WRAP_DIR}/lib${lib}_wrap.cpp
+        ${AUTO_WRAP_DIR}/lib${lib}.py
+        COMMENT "SWIG: use Python wrapper ${AUTO_WRAP_DIR}/lib${lib}.py"
+    )
+
     # include Python and Numpy headers and link to Python shared library
     target_include_directories(${lib} PRIVATE ${Python3_INCLUDE_DIRS} ${Python3_NumPy_INCLUDE_DIRS})
     target_link_libraries(${lib} PRIVATE ${Python3_LIBRARIES})
 
     set_target_properties(${lib} PROPERTIES
         _LIBRARY_PY "${AUTO_WRAP_DIR}/lib${lib}.py"
-        )
+    )
+
+    add_dependencies(${lib} lib${lib}_py_wrappers)
+
+    if((CLANG) OR (GCC))
+        # suppress warnings from auto-generated code (last updated for Swig 4.0.1)
+        set_source_files_properties(${AUTO_WRAP_DIR}/lib${lib}_wrap.cpp
+            PROPERTIES COMPILE_OPTIONS
+            "\
+-Wno-unused-parameter;\
+-Wno-missing-field-initializers;\
+-Wno-sometimes-uninitialized;\
+-Wno-deprecated-declarations")
+    endif()
+
+    # add SWIG-produced C++ wrapper source code to library sources
+    get_target_property(source_files ${lib} SOURCES)
+    list(APPEND source_files ${AUTO_WRAP_DIR}/lib${lib}_wrap.cpp)
+    set_target_properties(${lib} PROPERTIES
+        SOURCES "${source_files}")
 
-    install(FILES "${AUTO_WRAP_DIR}/lib${lib}.py"
-        DESTINATION ${destination_python} COMPONENT Libraries)
+    if(BA_CPP_API)
+        install(FILES ${AUTO_WRAP_DIR}/swig_runtime.h
+            DESTINATION ${destination_include}/Wrap COMPONENT Headers)
+    endif()
 
 endfunction()