Design Meeting Notes, 7/26/2024

[andrewbranch]

PR: error on variables that are used but never initialized

#55887

• new error on variable declaration when a use occurs inside a block scope
• the reason we don't previously error is we can't see the whole control flow graph—we only error in cases where a control flow walk produces certainty that there's no initialization
• the strategy in the PR is to walk the whole AST and error if there are no assignments anywhere
• implementation isn't quite right
  • leverages the unused variable code, but maybe should be in control flow instead,
  • errors would occur on use sites instead of declaration
    • counterpoint: the fix is going to be at the declaration
    • countercounterpoint: sure, but then you just go-to-def. It's a little harder to go to the references that are causing the error
  • introduces an extra property on symbols, memory hit, 0.5% time increase as-is, possibly unavoidable but maybe some is due to the extra property
• next steps: pass on feedback
  • add some code in checkIdentifier
  • do some stuff with isPastLastAssignment