Make tsserver.js a library

[Andrew Casey (amcasey)]

VS Code (and probably others) currently consumes both tsserver.js and
typescript.js, even though they have essentially the same content. This
change makes it possible to use tsserver.js for both purposes, by
suppressing the server startup code (including requires) and adding a
declaration file (stripped of internals).

[Andrew Casey (amcasey)]

I bet there's a cleverer way to skip the body of server.ts and I'd be happy to hear it.

[Andrew Casey (amcasey)]

FYI Matt Bierner (@mjbvz), hopefully, this will save VS Code 8MB or so.

[Andrew Casey (amcasey)]

Do I need to hook the new .d.ts file up to some sort of baseline/validation system?

[Wesley Wigham (weswigham)]

If we're considering this, the tsserverlibrary build is already this minus the startup code - perhaps we should just merge them?

[Andrew Casey (amcasey)]

Wesley Wigham (@weswigham) What does "merge them" mean in this context? Drop tsserverlibrary?

[Wesley Wigham (weswigham)]

tsserverlibrary's build tasks already have the declaration files and API baselining set up - so copying the conditional startup code into the tsserverlibrary entrypoint, then renaming it to tsserver (after deleting the old tsserver tasks/folder), I imagine (so, sort-of dropping it, yes, since name-wise, it'd be gone).

[Andrew Casey (amcasey)]

I've done my best to port the functionality of tsserverlibrary to tsserver, but they had slightly different watch functionality, so it might not be exact.

[Andrew Casey (amcasey)]

Force update was just a rebase. No manual merging required.

[Wesley Wigham (weswigham)]

This looks OK to me; but we should also have Ron Buckton (@rbuckton) take a look over the build changes and Ryan Cavanaugh (@RyanCavanaugh) validate when we wanna take the API break (since we'll no longer be shipping a file named tsserverlibrary - though we could symlink it to preserve compatibility, admittedly).

[Andrew Casey (amcasey)]

There's a weird quirk there actually - unless we manually delete it next time we update the LKG, we'll continue to ship the old one. (See also #39330)

[Wesley Wigham (weswigham)]

AFAIK when we rewrote the LKG script, the only reason it doesn't automatically delete dead files was because there was some .json document or something which seemed dead but was also potentially consumed by VS (and may even be gone by now - or I could be thinking of typesMap.json, don't know), IIRC from a conversation from years ago.

[Andrew Casey (amcasey)]

This would be a hack, so we're not going to pursue it.