Make more options common between builds

--keep-going isn't available until sphinx 2.0
-W turns warnings into errors which should help jenkins figure out that
the build finished with warnings

buildconfig/CMake/FindSphinx.cmake

@@ -45,10 +45,15 @@ find_package_handle_standard_args(Sphinx REQUIRED_VARS SPHINX_PACKAGE_DIR SPHINX
 
 # sphinx.__main__ was introduced in version 1.3.
 # Prior to this we need to pass sphinx.__init__ to -m
+set(SPHINX_MAIN "sphinx.__init__") # for very old sphinx
+set(SPHINX_NOCOLOR "")
+set (SPHINX_KEEPGOING "")
 if(SPHINX_VERSION VERSION_GREATER_EQUAL "1.3")
-  set(SPHINX_MAIN "sphinx")
+  set(SPHINX_MAIN "sphinx")  # sphinx can be called as a module
+  # arguments new in sphinx 1.3
   set(SPHINX_NOCOLOR "--no-color")
-else()
-  set(SPHINX_MAIN "sphinx.__init__")
-  set(SPHINX_NOCOLOR "")
+endif()
+if(SPHINX_VERSION VERSION_GREATER_EQUAL "2.0")
+  # arguments new in sphinx 2.0
+  set (SPHINX_KEEPGOING "--keep-going")
 endif()

dev-docs/CMakeLists.txt

@@ -8,10 +8,11 @@ set(DOCTREE_DIR ${CMAKE_CURRENT_BINARY_DIR}/doctree)
 # We try to execute Sphinx directly through python -m to avoid problems with the
 # startup scripts on Windows. They are not always reliable as they can have
 # hardcoded paths in them.
+# -W turns warnings into errors
 add_custom_target(dev-docs-${BUILDER}
                   COMMAND ${Python_EXECUTABLE} -m ${SPHINX_MAIN} ${SPHINX_NO_COLOR}
                           -w dev_docs_warnings.txt
-                          -W --keep-going -b ${BUILDER}
+                          -W ${SPHINX_KEEPGOING} -b ${BUILDER}
                           -d ${DOCTREE_DIR} ${CMAKE_CURRENT_LIST_DIR}/source
                           ${OUT_DIR}
                   COMMENT "Building html developer documentation")

docs/CMakeLists.txt

@@ -49,7 +49,8 @@ function (add_sphinx_build_target builder math_renderer)
     set(conf_builder ${SPHINX_CONF_DIR}/conf-${builder}.py)
   endif()
 
-  set(sphinx_options ${SPHINX_NOCOLOR} -b ${builder} -d ${DOCTREES_DIR})
+  # -W turns warnings into errors
+  set(sphinx_options -W ${SPHINX_NOCOLOR} ${SPHINX_KEEPGOING} -b ${builder} -d ${DOCTREES_DIR})
   # add a tag to differentiate between html/qthelp in conf
   if(ARGC GREATER 3)
     set(sphinx_options ${sphinx_options} -t ${ARGV3})