Merge branch 'feature/fix-cmake-documentation-without-doxylocal' into 'master'

[cmake][bugfix] Make CMake Doxygen creation work for modules without Doxylocal

When creating Doxygen documentation, CMake currently assumes that all
modules have a Doxylocal file, which is in fact only present in
dune-common right now. That file is then used as both a dependency and a
file reading input, causing CMake errors.

This patch fixes the problem by testing for the presence of Doxylocal
and only including it in the build process if it was found.

See merge request !61
(cherry picked from commit 4b1fb7c8)

Signed-off-by: Steffen Müthing <muething@dune-project.org>

cmake/modules/DuneDoxygen.cmake

@@ -27,11 +27,23 @@ add_custom_target(doxygen_install)
 # Doxyfile[.in] files needed to doxygen.
 MACRO (prepare_doxyfile)
   message(STATUS "using ${DOXYSTYLE_FILE} to create doxystyle file")
-  set(make_doxyfile_command ${CMAKE_COMMAND} -D DOT_TRUE=${DOT_TRUE} -D DUNEWEB_TRUE=\# -D ProjectName=${ProjectName} -D DUNE_MOD_VERSION=${DUNE_MOD_VERSION} -D DOXYSTYLE=${DOXYSTYLE_FILE}  -D DOXYLOCAL=${CMAKE_CURRENT_SOURCE_DIR}/Doxylocal -D abs_top_srcdir=${CMAKE_SOURCE_DIR} -D srcdir=${CMAKE_CURRENT_SOURCE_DIR} -D top_srcdir=${CMAKE_SOURCE_DIR} -P ${SCRIPT_DIR}/CreateDoxyFile.cmake)
-  add_custom_command (OUTPUT Doxyfile.in Doxyfile
-    COMMAND ${make_doxyfile_command}
-    COMMENT "Creating Doxyfile.in"
-    DEPENDS ${DOXYSTYLE_FILE} ${CMAKE_CURRENT_SOURCE_DIR}/Doxylocal)
+
+  # check whether module has a Doxylocal file
+  file(_DOXYLOCAL PATHS ${CURRENT_SOURCE_DIR} NO_DEFAULT_PATH)
+
+  if(_DOXYLOCAL)
+    set(make_doxyfile_command ${CMAKE_COMMAND} -D DOT_TRUE=${DOT_TRUE} -D DUNEWEB_TRUE=\# -D ProjectName=${ProjectName} -D DUNE_MOD_VERSION=${DUNE_MOD_VERSION} -D DOXYSTYLE=${DOXYSTYLE_FILE}  -D DOXYLOCAL=${CMAKE_CURRENT_SOURCE_DIR}/Doxylocal -D abs_top_srcdir=${CMAKE_SOURCE_DIR} -D srcdir=${CMAKE_CURRENT_SOURCE_DIR} -D top_srcdir=${CMAKE_SOURCE_DIR} -P ${SCRIPT_DIR}/CreateDoxyFile.cmake)
+    add_custom_command (OUTPUT Doxyfile.in Doxyfile
+      COMMAND ${make_doxyfile_command}
+      COMMENT "Creating Doxyfile.in"
+      DEPENDS ${DOXYSTYLE_FILE} ${CMAKE_CURRENT_SOURCE_DIR}/Doxylocal)
+  else()
+    set(make_doxyfile_command ${CMAKE_COMMAND} -D DOT_TRUE=${DOT_TRUE} -D DUNEWEB_TRUE=\# -D ProjectName=${ProjectName} -D DUNE_MOD_VERSION=${DUNE_MOD_VERSION} -D DOXYSTYLE=${DOXYSTYLE_FILE}  -D DOXYLOCAL=${CMAKE_CURRENT_SOURCE_DIR}/Doxylocal -D abs_top_srcdir=${CMAKE_SOURCE_DIR} -D top_srcdir=${CMAKE_SOURCE_DIR} -P ${SCRIPT_DIR}/CreateDoxyFile.cmake)
+    add_custom_command (OUTPUT Doxyfile.in Doxyfile
+      COMMAND ${make_doxyfile_command}
+      COMMENT "Creating Doxyfile.in"
+      DEPENDS ${DOXYSTYLE_FILE})
+  endif()
   add_custom_target(Doxyfile DEPENDS Doxyfile.in Doxyfile)
 ENDMACRO (prepare_doxyfile)
 

cmake/scripts/CreateDoxyFile.cmake

 #For now we just support appending Doxyfile and Doxylocal
 FILE(READ ${DOXYSTYLE} file_contents)
 FILE(WRITE Doxyfile.in ${file_contents})
-FILE(READ ${DOXYLOCAL} file_contents)
+if(_DOXYLOCAL)
+  FILE(READ ${DOXYLOCAL} file_contents)
+endif()
 FILE(APPEND Doxyfile.in ${file_contents})
 
 # configure_file does not work as it insists an existing input file, which in our