link from *Compile Log* to News section on upgrading?

["Drew Adams" <drew.adams@oracle.com>]

Possible feature for discussion after the release (sending now because I'll
forget ;-)):

In *Compile Log*, what about having warning and error messages that mention
deprecated or obsolete stuff contain a link to the doc (e.g. News or Info)
that tells people what to use now (how to upgrade their code) - whenever
that info is available?

For example, instead of seeing just:

  Warning: `directory-sep-char' is an obsolete variable (as
           of Emacs 21.1); do not use it.

the text `directory-sep-char' would be linked to its discussion in News or
Info.

It's not always obvious, from the message itself, what the necessary upgrade
fix is. Some messages, such as this one, say just "do not use it". Some say
just "not necessary any more". What, if anything, to replace such
occurrences with is not always obvious, from the message itself. People are
more likely to upgrade code if they can quickly find appropriate
instructions for how to do that.