The OncePerASTToken machinery lets us automatically cancel "stale"
requests after a new one comes in. This avoid wasting time processing
requests that have been superceded, which is common for cursor-info, but
sometimes you really want to get results even later, so this commit adds
a way to opt out of the cancellation.
Incidentally, disable cancellation of name translation, which doesn't
really make sense and no one should be relying on that.
rdar://problem/31905379
- Make the Demangle header match the other headers in the doc (e.g.,
double hash)
- Add a table of contents that is sorted alphabetically by request key
with a link to the header in the document
- Convert `Protocol.txt` to `Protocol.md`, and use valid Markdown
syntax.
- Spruce up the documentation in the "code completion": more details on
how to test via the REPL, clearer sentences, etc.
- Fix an error in which `sourcekitd-test -req=complete -offset=<offset>`
used the incorrect option `-cc-offset`.
The code goes into its own sub-tree under 'tools' but tests go under 'test',
so that running 'check-swift' will also run all the SourceKit tests.
SourceKit is disabled on non-darwin platforms.
