fix: do not flag block argument shadowing across mutually exclusive branches in Lint/ShadowingOuterLocalVar#824
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Sija merged 2 commits intoMay 11, 2026
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…ranches in `Lint/ShadowingOuterLocalVar`
The rule used a purely positional check (`declared_before?`) to decide
whether a block or proc argument shadowed an outer local variable. As a
result it produced false positives whenever the outer assignment lived
in a control-flow branch that could not reach the block argument:
```cr
if cond
x = 1
else
foo { |x| } # incorrectly flagged
end
```
Add a localized AST-walking check that records the branch path of the
block argument and each assignment of the candidate variable. When every
assignment diverges from the argument's path at a common branching
ancestor, the outer assignment cannot reach the block argument and the
warning is suppressed.
Handles `if`/`unless`, `case`/`when`/`else`, `select`/`when`/`else`, and
`begin`/`rescue`/`else` (body and `ensure` always run, so they remain
non-exclusive). The visitor is cached per outer scope across candidates
within a single rule invocation to avoid re-walking the same AST.
Sija
reviewed
May 11, 2026
…lly exclusive branches
Sija
deleted the
fix-shadowing-outer-local-var-mutually-exclusive-branches
branch
Sija
changed the title
Lint/ShadowingOuterLocalVar
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Closes #819
Added a localized AST-walking check (
mutually_exclusive_branches?) that records the branch path of the block argument and each assignment of the candidate variable. When every assignment diverges from the argument's path at a common branching ancestor, the outer assignment cannot reach the block argument and the warning is suppressed.No
Branch/Branchableinfrastructure was reintroduced (recently removed in #795) — the check is contained in the rule.