pi-lens/rules/ast-grep-rules/rules-disabled/no-method-field-name-collision.yml

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# DISABLED (no issue): rule fires on every Python class with both
# a `def` method and a `self.X =` assignment, because ast-grep
# patterns can't compare two metavariables for case-insensitive
# equality (the `method name` vs `attribute name` case-insensitive
# match that SonarCloud S1845 requires). On PostHog the rule fires
# 2,554 times — almost every class triggers it. A proper fix
# would require either (a) cross-node name comparison outside of
# ast-grep's pattern matcher, or (b) a Python-specific type-aware
# analyzer (mypy/pyright). Keeping the rule and fixture in
# rules-disabled/ so the design intent is documented and a future
# implementation can pick it up.
id: no-method-field-name-collision
language: Python
message: "Methods and field names should not differ only by capitalization"
severity: warning
note: |
  Port of SonarCloud python:S1845.

  A class with both `def get_X(self)` and `self.x = ...` is
  confusing — two attributes that differ only in capitalization
  may collide on case-insensitive lookups or confuse readers.

  This rule uses ast-grep **patterns** to detect a class that
  contains BOTH a method definition (`def $F(self, ...)`) and
  a field assignment (`self.$X = ...`). The `(?i)` regex on
  the class text is necessary because ast-grep's pattern
  matcher doesn't support case-insensitive metavariable
  matching out of the box.

  This is an approximate check — full S1845 detection requires
  tracking all definitions and assignments to check for exact
  name overlap (case-insensitively). The rule flags any class
  with both patterns for manual review.
metadata:
  sonar: S1845
rule:
  all:
    - kind: class_definition
    - regex: '(?i)def\s+\w+\(self'
    - has:
        pattern: "self.$FIELD = $VALUE"
        stopBy: end