pi-lens/rules/ast-grep-rules/rules-disabled/shadow-err-variable.yml

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# DISABLED (#PR-319): shadow-err-variable rule is too imprecise
#
# Original rule from RealHarshThakur/ast-grep-go attempted to detect Go
# `err := ...` variable shadowing inside if/for/switch blocks. The
# implementation relies on Go 1.22+'s loop-scope semantics that ast-grep
# 0.42.0 can't detect statically.
#
# The fallback pattern (matching `err := $_` inside if/for/switch) is
# too narrow: Go's common multi-assignment idiom `val, err := tryRecover()`
# isn't a `err := $_` statement — it's a tuple destructuring with `err`
# on the LHS. The rule's "inside: kind: if_statement" only matches
# top-level if blocks, not nested blocks.
#
# Net result: rule fires on nothing useful (test fixtures don't produce
# matches). Either needs a tree-sitter-based implementation (which can
# track scope) or should stay disabled.

id: shadow-err-variable
language: go
severity: warning
message: "Error variable 'err' shadowed in inner scope; original error reference is lost"
note: |
  Limited utility: matches `err := $_` statements inside if/for/switch
  blocks. Multi-assignment (`val, err := x()`) is not detected because
  the LHS is a tuple, not just `err`.
rule:
  pattern: err := $_
  inside:
    any:
      - kind: if_statement
      - kind: for_statement
      - kind: expression_switch_statement
    stopBy: end
has_fix: false
tags:
  - go
  - error-handling
  - limited