[Dot Shorthands] 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

Estimated work

• Parser

  • Need changes to identify when we have a shorthand, add all selectors
  • Recovery/error when . followed by a keyword?, some random symbol
  • Expressions can’t start with .

• AST enhancements (AstBuilder)

  • New AST type to represent the enum shorthand
  • . operator
  • And then the rest of the expression
  • Based on Paul’s prototype we need to represent a non-existent target (which he does with a “MAGIC” SimpleIdentifier)

• Summary support

  • Summaries record constants so I might need to do work here? Check with Konstantin

• Resolution

  • ResolverVisitor (type-based resolution)
    • Paul’s prototype used a stack of type schemas (named _enumShorthands). “When the ResolverVisitor enters the enum shorthand context node, it pushes the context onto this stack; when it leaves it, it pops it back off”
    • Work needed, tests needed.
    • == work in the TypeAnalyzer as well.

• Constant evaluation

  • We allow consts for enum shorthands.
  • Use the new AST.
  • Tests

• Index and search

  • Not entirely sure?
  • We can refer to a class without naming it. Might need updating?

• Warnings (annotation-based, unused*, strict-mode-based, a few others)

  • ErrorVerifier (report other errors and warnings)
    • Error when we are missing the context type
    • Error with asymmetric == and != (These errors might just belong in the ResolverVisitor?)

• NodeLintRegistry

  • If we make a new AST node representing enum shorthands, should add it to this.