sphinx: report errors when dependencies are not met

To build the Sphinx documentation, we have the following dependencies:
* sphinx
* sphinx_rtd_theme
* pyyaml

If any of these dependencies are missing, we might end up with some
cryptic error messages. This patch adds better error reporting when
dependencies are not met.

(From yocto-docs rev: 19df8d1ec56dc2ecb44122288cc53e84237fab69)

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

1 files changed, 4 insertions, 0 deletions

diff --git a/documentation/Makefile.sphinx b/documentation/Makefile.sphinx
index c663c29540..c9518558bb 100644
--- a/documentation/Makefile.sphinx
+++ b/documentation/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)