bitbake: docs: sphinx: report errors when dependencies are not met

(Bitbake rev: 9ae5cce76693d7c12396cee1183aaf371bb3d66c)

Signed-off-by: Nicolas Dechesne <nicolas.dechesne@linaro.org>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/doc/Makefile.sphinx

@@ -9,6 +9,10 @@ SOURCEDIR     = .
 BUILDDIR      = _build
 DESTDIR       = final
 
+ifeq ($(shell if which $(SPHINXBUILD) >/dev/null 2>&1; then echo 1; else echo 0; fi),0)
+$(error "The '$(SPHINXBUILD)' command was not found. Make sure you have Sphinx installed")
+endif
+
 # Put it first so that "make" without argument is like "make help".
 help:
 	@$(SPHINXBUILD) -M help "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXOPTS) $(O)

bitbake/doc/conf.py

@@ -73,7 +73,13 @@ rst_prolog = """
 # The theme to use for HTML and HTML Help pages.  See the documentation for
 # a list of builtin themes.
 #
-html_theme = 'sphinx_rtd_theme'
+try:
+    import sphinx_rtd_theme
+    html_theme = 'sphinx_rtd_theme'
+except ImportError:
+    sys.stderr.write("The Sphinx sphinx_rtd_theme HTML theme was not found.\
+    \nPlease make sure to install the sphinx_rtd_theme python package.\n")
+    sys.exit(1)
 
 # Add any paths that contain custom static files (such as style sheets) here,
 # relative to this directory. They are copied after the builtin static files,