Re: [PATCH v4 2/2] meson: Deserialize the man pages and html builds

[Paolo Bonzini <pbonzini@redhat.com>]

On 5/3/23 22:39, Fabiano Rosas wrote:
> For the documentation builds (man pages & manual), we let Sphinx
> decide when to rebuild and use a depfile to know when to trigger the
> make target.
> 
> We currently use a trick of having the man pages custom_target take as
> input the html pages custom_target object, which causes both targets
> to be executed if one of the dependencies has changed. However, having
> this at the custom_target level means that the two builds are
> effectively serialized.
> 
> We can eliminate the dependency between the targets by adding a second
> depfile for the man pages build, allowing them to be parallelized by
> ninja while keeping sphinx in charge of deciding when to rebuild.
> 
> Since they can now run in parallel, separate the Sphinx cache
> directory of the two builds. We need this not only for data
> consistency but also because Sphinx writes builder-dependent
> environment information to the cache directory (see notes under
> smartquotes_excludes in sphinx docs [1]).
> 
> Note that after this patch the commands `make man` and `make html`
> only build the specified target. To keep the old behavior of building
> both targets, use `make man html` or `make sphinxdocs`.
> 
> 1- https://www.sphinx-doc.org/en/master/usage/configuration.html

Unfortunately this breaks CentOS 8, which has an older version of ninja:

ninja: error: build.ninja:16369: multiple outputs aren't (yet?) 
supported by depslog; bring this up on the mailing list if it affects you

This was fixed in ninja 1.10.0.

Paolo