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Fix remove_unused_variable rule bug with used unassigned variables #275

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Merged
jeparlefrancais merged 1 commit into from
Jun 19, 2025
Merged

Fix remove_unused_variable rule bug with used unassigned variables #275

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32 changes: 24 additions & 8 deletions src/rules/remove_unused_variable.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -129,22 +129,33 @@ impl NodeProcessor for RemoveUnusedVariableProcessor {
.collect();

let length = assignments.len();
let mut remaining_unassigned_variables = Vec::new();

if let Some((last, value)) = assignments.last_mut() {
let remaining =
assign.iter_variables().zip(usages.iter()).skip(length);
if self.evaluator.can_return_multiple_values(value) {
last.extend(
assign.iter_variables().zip(usages.iter()).skip(length),
last.extend(remaining);
} else {
remaining_unassigned_variables.extend(
remaining
.filter(|(_, used)| **used)
.map(|(identifier, _)| identifier.clone()),
);
}
}

let mut variables = Vec::new();
let mut values = Vec::new();
let mut values: Vec<_> = remaining_unassigned_variables
.iter()
.map(|_| Expression::nil())
.collect();
let mut variables = remaining_unassigned_variables;

for (mut identifiers, value) in assignments {
if !self.evaluator.has_side_effects(value) {
while identifiers.last().filter(|(_, used)| !*used).is_some() {
identifiers.pop();
}
let mut last_popped = None;

while identifiers.last().filter(|(_, used)| !*used).is_some() {
last_popped = identifiers.pop();
}

if !identifiers.is_empty() {
Expand All @@ -154,6 +165,11 @@ impl NodeProcessor for RemoveUnusedVariableProcessor {
.map(|(identifier, _)| identifier.clone()),
);
values.push(value.clone());
} else if self.evaluator.has_side_effects(value) {
if let Some((last_identifier, _)) = last_popped {
variables.push(last_identifier.clone());
values.push(value.clone());
}
}
}

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3 changes: 3 additions & 0 deletions tests/rule_tests/remove_unused_variable.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -56,6 +56,9 @@ test_rule!(
remove_unused_variable_but_keep_require_side_effect("local _requireZero = require('./requireZero.roblox.lua')") => "require('./requireZero.roblox.lua')",
remove_unused_variable_but_keep_require_side_effect_in_parens("local _requireZero = (require('./requireZero.roblox.lua'))") => "require('./requireZero.roblox.lua')",
remove_unused_variable_but_keep_require_side_effect_in_parens_with_type_cast("local _requireZero = (require('./requireZero.roblox.lua') :: any)") => "require('./requireZero.roblox.lua')",
remove_unused_variable_but_not_initially_assigned_variable("local a, b = true b = false") => "local b = nil b = false",
remove_unused_variable_but_not_initially_assigned_variable_with_unused_trailing_variable("local a, b, c = true b = false") => "local b = nil b = false",
keep_used_variable_bounded_by_unused_variable_with_side_effect("local a, b, c = call() b = false") => "local a, b = call() b = false",
// remove variables that are used more than once, but never read
// remove_if_only_assigned("local a = true a = false") => "",
// remove_if_only_field_assigned("local a = {} a.foo = false") => "",
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