Ever since Sphinx variable reading operates at the AST level (bug
1071012), we don't technically need a fully configured environment in
order to generate the documentation!
This patch stubs out the config environment object with a fake one that
provides the only needed context to generate the Sphinx docs. This
allows us to build the Sphinx docs on a fresh clone of the tree with no
configure and with no object directory.
Read the Docs has a lovely Sphinx theme that beats the pants off the
built-in and default theme. And since it looks like MDN's Sphinx theme
is dead in the water, this gets us a nice UI win until the MDN theme
comes back from the dead.
The in-tree Sphinx docs have been broken since bug 1041941 because
processing moz.build files outside their context doesn't work.
Specifically, templates aren't loaded (because this information usually
comes from a parent moz.build file). A new execution mode is needed.
I tried to implement a proper execution mode. However, I kept running
into walls. While we should strive for a proper execution mode, this can
be a follow-up, tracked in bug 1058359.
This patch implements extraction of Sphinx variables from ast walking.
It is extremely low-level and definitely a one-off. But it solves the
problem at hand: |mach build-docs| will work after this patch is
applied.
