tools: rewrite js2c.cc in rust

[anonrig]

I wanted to see how adding more Rust would work with the existing toolchain & tools. There is no specific reason for this rewrite that can be justified other than the benefits of Rust over C++.

The code is a lot simpler and a lot readable now (as far as I can tell)

[nodejs-github-bot]

Review requested:

• @nodejs/gyp
• @nodejs/loaders
• @nodejs/startup

[joyeecheung]

I think for the code of js2c per-se moving to rust would be a fun exercise though most of the Rust over C++ benefit doesn't really apply for something that's just a build tool (if it weren't for the slowness, we could've stayed in Python). But taking build complexity into consideration it's not very worth it IMO e.g. it's only easy when js2c has no extra dependencies, but for changes like #62146 (which makes js2c link to V8) this would add more obstacles.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.71%. Comparing base (a9ac9b1) to head (29fad45).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff            @@
##             main   #62565    +/-   ##
========================================
  Coverage   89.70%   89.71%            
========================================
  Files         695      695            
  Lines      214213   214417   +204     
  Branches    41021    41065    +44     
========================================
+ Hits       192167   192354   +187     
  Misses      14113    14113            
- Partials     7933     7950    +17     

Files with missing lines	Coverage Δ
lib/internal/bootstrap/realm.js	96.21% <100.00%> (ø)
src/node_builtins.h	100.00% <ø> (ø)

... and 51 files with indirect coverage changes

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[Qard]

but for changes like #62146 (which makes js2c link to V8) this would add more obstacles.

The type-stripping itself is in Rust though, so that could just be plugged into a Rust version of js2c fairly easily and do translation for core TS files at build time. Might actually be a good thing to have this in Rust.

[marco-ippolito]

but for changes like #62146 (which makes js2c link to V8) this would add more obstacles.

The type-stripping itself is in Rust though, so that could just be plugged into a Rust version of js2c fairly easily and do translation for core TS files at build time. Might actually be a good thing to have this in Rust.

not really, it's a wasm. the problem of adding rust dependencies is vendoring