We don't need to build a whole new dev bundle just for this upgrade, since
we've already worked around the bug that it fixes, but it will get picked
up the next time we build the dev bundle for Meteor 1.8.2.
This ensures we wrap modules with a function to rename the `module`
identifier to something more reliable when the ImportScanner compiles
unanticipated modules imported from node_modules.
We ended up with two different versions of the reify package (0.19.0 and
0.19.1) in the last build of the dev bundle, which seems to have caused
the test failures.
On Linux, child processes that have exited may remain as <defunct>
"zombie" processes, which prevents process.kill(childPid, 0) from
throwing, so we need a different trick for detecting whether the child
process is still alive.
These changes pave the way for incrementally converting the implementation
of Meteor's command-line tool to TypeScript, which should have profound
benefits for self-documentation via types, as well as substantially
improving navigability and approachability for community contributors.
Just imagine being able to auto-complete the fields of the various
File-like classes currently floating around the codebase, instead of
having to track down their implementations every time. TypeScript was
designed with large projects like Meteor in mind, and it seems
increasingly irresponsible to forgo the benefits of a type system by
relying on the expertise of a few core contributors who know the codebase
inside and out. I am one of those few people, and I am very excited to
have the assistance of a type system, so I can only imagine how
transformative and empowering it will be for everyone else.
If you've ever wanted to get involved in core Meteor development, picking
a few meteor/tools modules to convert to TypeScript is a great way to get
to know that part of the codebase, while also making things easier for
everyone else who interacts with that code in the future.
Because we already compile meteor/tools using Babel, it makes the most
sense to use Babel's @babel/preset-typescript to compile .ts files:
https://babeljs.io/docs/en/next/babel-preset-typescript.html
Using Babel also means we get to keep all of our current advanced
compilation strategies, such as using Reify to compile module syntax:
https://www.npmjs.com/package/reify
Since we're using Babel, the meteor/tools/tsconfig.json file exists mostly
for the benefit of external tools like VSCode, rather than as a source of
truth for compilation behavior.
Despite our existing convention of including explicit .js file extensions
when importing modules, TypeScript and VSCode strongly encourage omitting
the file extension, so the import can be resolved to a .ts file in
development or a .js file when compiled. Although I find this ambiguity
somewhat unfortunate, it makes sense to follow community norms, at least
until Node.js begins supporting .ts modules by default.
The optimism package no longer knows anything about Fibers, but it does
export various helpers for managing execution contexts, one of which
(noContext) allows us to censor the current context for the duration of a
function call. By wrapping Fiber.yield with noContext, we keep distinct
Fibers from accidentally registering cache dependencies on one another.
