Re: [RFC] docs: remove documentation for unsupported releases

[Joseph Myers <joseph@codesourcery.com>]

On Wed, 9 Nov 2022, Michael Matz via Gcc-patches wrote:

> I think everything that's on the web server (even the 2.95 docu) has to be 
> reachable via a (reasonable) set of clicks from the main index.html.  It 
> doesn't need to be _directly_ from the main index.html, though.
> 
> Also, you simply might want to move the "Current Development" section 
> to the front if it's currently too cumbersome to reach.
> 
> (E.g. one could move the index of the obsolete versions to a different web 
> page, make that one un-indexable by google, but leave a trace to that one 
> from the main index.html).

Although we could use robots.txt to prevent indexing of the old 
documentation, that's not quite right, in that there's no problem with 
robots accessing the old documentation for any purpose (indexing, 
archiving, downloading a local copy of all the docs for an old version, 
etc.), just with showing it in a search engine in preference to a more 
recent version.  The logically correct way of directing search engines to 
the preferred version to index is <link rel="canonical">.

Suppose we could develop some reasonably reliable way of making automated 
substitutions in the HTML manuals for old versions.  (Make sure the 
original versions of the files, generated years ago, are backed up first!  
Indeed, when we want to revise such substitutions, we should go back to 
the original versions of the files to do so rather than piling one 
substitution on top of another - i.e. the original versions should be kept 
somewhere readily available for that purpose, just not directly in the web 
area.)  Then we could substitute such <link rel="canonical"> to point to a 
more recent release (that has a matching documentation page).  And as I 
mentioned at the Cauldron, I think having human-visible notices on the 
pages for old versions, linking to the corresponding page for human 
readers - like there are in old versions of the Python documentation - 
would be a good idea as well.

Maybe it would be hard to find matching pages in an automated way across 
the Sphinx transition - so all EOL versions before GCC 12 would end up 
pointing to corresponding pages in GCC 12 documentation and a more general 
index for later versions, rather than a corresponding page for a later 
version - but whatever can be done automatically in terms of 
rel="canonical" for search engines and a prominent notice at the top of 
each page for human readers still seems like it would be a significant 
improvement (and something that could be improved further incrementally).

-- 
Joseph S. Myers
joseph@codesourcery.com