Refactor identifier-usage-analyzer to use syntax-traverse

[Copilot]

The identifier-usage-analyzer was manually traversing all possible fully expanded syntactic forms using extensive syntax-class definitions. This approach required ~250 lines of boilerplate matching every kernel form, making it difficult to maintain compared to variable-mutability-analyzer which uses syntax-traverse and syntax-search.

Changes

• Removed manual syntax classes: Eliminated fully-expanded-top-level-form, fully-expanded-expression, fully-expanded-formals, and related classes that explicitly matched each kernel form
• Implemented using syntax-traversal primitives:
  • syntax-traverse labels identifiers with phase information
  • syntax-search finds binding sites (binding-site-identifiers) and usage sites (usage-site-identifiers)
  • Identifiers grouped by phase into the same binding table structure
• Net reduction: 114 lines (252 removed, 138 added)

The refactored implementation follows the same pattern as variable-mutability-analyzer for consistency.

Before vs After

Before (manual traversal):

(define-syntax-class (fully-expanded-expression phase)
  #:attributes (bound-ids-by-phase used-ids-by-phase)
  #:literal-sets ((kernel-literals #:phase phase))
  
  (pattern id:id
    #:attr bound-ids-by-phase (hash)
    #:attr used-ids-by-phase (hash phase (treelist (attribute id))))
  
  (pattern (let-values ([(id:id ...) (~var rhs (fully-expanded-expression phase))] ...)
             (~var body (fully-expanded-expression phase)) ...+)
    ; ... 10+ more lines per form)
  ; ... repeated for all kernel forms

After (syntax-search):

(define (usage-site-identifiers expanded-stx)
  (let loop ([expanded-stx expanded-stx] [phase 0])
    (syntax-search expanded-stx
      #:literal-sets ([kernel-literals #:phase phase])
      [(define-values (_ ...) rhs) (recur (attribute rhs))]
      [((~or let-values letrec-values) ([(_ ...) rhs] ...) body ...)
       (apply stream-append (append (map recur (attribute rhs))
                                    (map recur (attribute body))))]
      [id:id #:when (identifier? this-syntax) (stream (attribute id))])))

Original prompt

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This section details on the original issue you should resolve

<issue_title>Identifier usage analyzer should use syntax-traverse</issue_title>
<issue_description>The implementation of identifier-usage-analyzer is a manual traversal over all possible fully expanded syntactic forms. However, it would be much easier to implement it the same way this logic is implemented in the variable mutability analyzer: as a series of syntax traversal using syntax-search and syntax-traverse.</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Identifier usage analyzer should use syntax-traverse #686

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[coveralls]

Pull Request Test Coverage Report for Build #94

Details

• 89 of 91 (97.8%) changed or added relevant lines in 1 file are covered.
• 3 unchanged lines in 1 file lost coverage.
• Overall coverage increased (+0.02%) to 93.558%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
default-recommendations/analyzers/identifier-usage.rkt	89	91	97.8%

Files with Coverage Reduction	New Missed Lines	%
default-recommendations/analyzers/identifier-usage.rkt	3	95.14%

Totals
Change from base Build #90:	0.02%
Covered Lines:	14421
Relevant Lines:	15414

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💛 - Coveralls