Design Meeting Notes, 1/25/2023

[DanielRosenwasser]

ignoreDeprecations in TS 4.9

#51909

• importsNotUsedAsValues and preserveValueImports are deprecated in favor of verbatimModuleSyntax
• You're supposed to use the ignoreDeprecations flag to temporarily disable this as you migrate off the flags.
• Can't make a tsconfig.json that works for both 4.9 and 5.0.
• Nice to be able to let a team move over incrementally.
• Want to bring ignoreDeprecations back to 4.9
  • Helps with editor scenarios too while VS Code still ships 4.9.

Moving from barrel imports in our codebase

#51455
#51590

• In our migration to modules, we use barrel imports to keep things simple-ish, keep initialization order.
• Big task, but @a-tarasyuk took it on.
• Had to resolve issues with cycles, seems like it's fine.
  • Gives some benefits that now some tools can analyze our codebase to detect cycles.
• Makes moving code around harder.
  • But that is an empathy gap between us an our users.
  • We should think about editor features to help here in 5.1
  • Also, would be nice if we could detect cycles in some way.
• Some instances where we still use (ts as any).Yadda for preserved const enums.
• By explicitly declaring what the parser imports from, other tools can more-easily tree shake from us.
• Also Use ESM for our executables (tsc, tsserver, typingsInstaller) #51440
  • Previously, these attempts ran into crashes due to circularities.
  • Fixing the cycles would allow many of these to operate correctly.
• So Convert debug namespace into a module, direct import #51455
  • Seems uncontroversial.
• Use ESM for our executables (tsc, tsserver, typingsInstaller) #51440
  • Something to be said about flat files.
  • Would be nice to ship an ESM version
• Moving to direct imports?
  • Seems okay.

Import Sorting

#52090

• ESLint doesn't tie-break sorting well - i.e. if you import hasDecorators and HasDecorators, the two might flip.
  • So it's not a stable sort!?
  • No.
• We made more internationally-sensitive changes in Add option for organize imports case sensitivity #51733.
  • Compatible with what? ESLint doesn't give deterministic (or is it stable?) sorting, we do.
  • Based on eslint/sort-imports.
    • They used toUppercase, we did toLowercase for case insensitivity.
    • Noticeable for ASCII characters in between - namely the underscore (_)
• Organize imports collation #52115
  • Uses Intl.Collator to do sorting if desired.
  • Compatible with eslint-plugin-simple-import-sort.
• Does Prettier do import sorting?
  • No.
  • Thankfully. Don't need 30 tools fighting with each other. 😅
• dprint does if you want, and it's compatible!
• Sounds like we have good-enough coverage to say "we support all of them."
• So okay with changing our repo to new linter options?
  • Seems fine.
• Aside: need to copy settings over for auto-imports(?)

[IllusionMH]

Helps with editor scenarios too while VS Code still ships 4.9.

Shouldn't they use local workspace TS 5.0 version? Or is it about web only case?

[DanielRosenwasser]

IIRC, VS Code doesn't use the workspace version until you opt into it - but either way, your team might be using a local workspace version of 4.9 while you are trying to upgrade to 5.0.

[MartinJohns]

IIRC, VS Code doesn't use the workspace version until you opt into it

Yeah, by default VS Code uses whatever TypeScript version it ships with (currently 4.9). This is a security feature, because the locally installed TypeScript version could potentially be malicious code.

[lukeapage]

Prettier can sort imports via a plug-in - we use it because it has better overall support than eslint. https://github.com/trivago/prettier-plugin-sort-imports

[DanielRosenwasser]

Hopefully the natural-sort utility they use is compatible with the organizeImportsNumericCollation from #52115.