Some buildernames does not support caching

[marxin]

I noticed that e.g. HTML builder can cache output and does not generate anything if there's no change:

$ time make -j16 html
sphinx-build -b "html" -d _build/doctrees  -j auto  . "_build/html"
Running Sphinx v4.0.2
loading pickled environment... done
building [mo]: targets for 0 po files that are out of date
building [html]: targets for 0 source files that are out of date
updating environment: 0 added, 0 changed, 0 removed
looking for now-outdated files... none found
no targets are out of date.
build succeeded.

The HTML pages are in _build/html.

real	0m0.686s
user	0m0.610s
sys	0m0.076s

while e.g. manpages generation always writes:

$ time make -j16 man
sphinx-build -b "man" -d _build/doctrees  -j auto  . "_build/man"
Running Sphinx v4.0.2
loading pickled environment... done
building [mo]: targets for 0 po files that are out of date
building [man]: all manpages
updating environment: 0 added, 0 changed, 0 removed
looking for now-outdated files... none found
writing... gcc.1 { gcc-command-options/description } done
build succeeded.

The manual pages are in _build/man.

real	0m5.142s
user	0m5.009s
sys	0m0.133s

As seen, looking for now-outdated files... none found is printed but output files are re-generated.

[AA-Turner]

To confirm, this change makes it so that the man builder no longer unconditionally writes files?

A

[marxin]

To confirm, this change makes it so that the man builder no longer unconditionally writes files?

Yes.

[floam]

Reopen?

[AA-Turner]

Do you have a different proposed fix?

A