[Wildcard Variables] Analyzer Implementation

[kallentu]

This meta issue tracks all the analyzer implementation work items. Referenced from: https://github.com/dart-lang/sdk/blob/main/pkg/analyzer/doc/process/new_language_feature.md

Work Items

• [ ] AST enhancements (AstBuilder)
  • For both locals and parameters, distinguish between wildcard and regular declarations. Keep element for future use in areas like renaming.
• [ ] Resolution of directives
  • May need some changing depending on https://github.com/dart-lang/language/issues/3799
• [X] Element model
• [X] Type system updates
• [X] Summary support
  • Make sure still works as intended.
• [ ] Resolution
  • [ ] ResolutionVisitor (resolve types)
  • [ ] ScopeResolverVisitor (resolve simple identifiers by scope)
    • Don't put wildcard variables in scope.
  • [ ] ResolverVisitor (type-based resolution)
• [ ] Constant evaluation
  • Verify with some tests that constants still work as expected with wildcards.
• [X] Index and search
• [ ] Warnings (annotation-based, unused*, strict-mode-based, a few others)
  • [ ] InheritanceOverrideVerifier (report errors and warnings related to overrides)
    • Make sure we can override methods and use _ for unused parameters.
  • [ ] ErrorVerifier (report other errors and warnings)
    • From #initializing-formals, “Even though the parameters no longer collide, it is still an error to have two initializing formals named _”
    • From #super-parameters, “An occurrence of super._ as a declaration of a formal parameter in a constructor is a compile-time error.”
    • [ ] #55905
      • Discussion: https://github.com/dart-lang/language/issues/3798
    • [ ] #55920
    • [x] #56089
    • [x] #56092
  • [X] FfiVerifier (report errors and warnings related to FFI)
  • [ ] Unused elements warnings
    • [x] UNUSED_ELEMENT
      • [x] https://github.com/dart-lang/sdk/commit/f517dd6436fb6a14e52b10e04f20fe32b75433ee
    • [ ] UNUSED_LOCAL_VARIABLE
      • [ ] https://github.com/dart-lang/sdk/issues/55719
    • [ ] UNUSED_CATCH_CLAUSE
      • [ ] #55723
    • [x] UNUSED_CATCH_STACK
      • [x] https://github.com/dart-lang/sdk/issues/55721
    • [x] UNUSED_FIELD
      • [x] #55862
  • [x] Dead code
    • [x] local function declarations: https://github.com/dart-lang/sdk/commit/a446cd96670bd461185ae58048ed02bb223468a1
  • [x] @useResult verification should not warn on results assigned to wildcards: https://github.com/dart-lang/sdk/commit/a86ec25ffb90cbbe389ea6c4a22f33248deb70d0
• [X] ExitDetector
• [X] NodeLintRegistry

[kallentu]

@pq I updated what needs to be done in the analyzer with a short note from the kickoff. If it's easier to track with singular issues, we can do that too.

I suspect this work can start soon. I'm currently slowly adding language tests to the repo and I usually use those as a good indicator of what's working and what isn't.

[pq]

@kallentu:

From #super-parameters, “An occurrence of super._ as a declaration of a formal parameter in a constructor is a compile-time error.”

This seems out of sync with the current spec. Could you take a look?

[kallentu]

@kallentu:

From #super-parameters, “An occurrence of super._ as a declaration of a formal parameter in a constructor is a compile-time error.”

This seems out of sync with the current spec. Could you take a look?

Ah yes, you're right. I updated the task, feel free to remove it or change it. super._ isn't a compile time error.

[kallentu]

Marking this as done for the most part. Feature has shipped.