Skip fixing unused variable when they have references

selene-lib/src/lints/unused_variable.rs

@@ -172,6 +172,13 @@ impl Lint for UnusedVariableLint {
                     fixed_code = None;
                 }
 
+                // Applying fix would cause references to reference the old variable. It's possible to also rename those
+                // references as well, but we'd need to check each of their scopes for potentially colliding variables.
+                // Cargo just doesn't apply a fix in these cases.
+                if !variable.references.is_empty() {
+                    fixed_code = None;
+                }
+
                 let write_only = !analyzed_references.is_empty();
 
                 diagnostics.push(Diagnostic::new_complete(

selene-lib/tests/lints/unused_variable/blocks.fixed.diff

@@ -1,15 +1,12 @@
  -- Functions
 -local function unusedFunction()
--    local unusedVariableA = 1
--    local unusedVariableB = 1
 +local function _unusedFunction()
-+    local _unusedVariableA = 1
-+    local _unusedVariableB = 1
+     local unusedVariableA = 1
+     local unusedVariableB = 1
  end
 
  print(unusedVariableB)
--local overidden = true
-+local _overidden = true
+ local overidden = true
 
  local function overridesIt()
      local overidden = false

selene-lib/tests/lints/unused_variable/edge_cases.fixed.diff

@@ -1,8 +1,6 @@
  local foo = 1
--local foo = foo + 1
--local bar = bar
-+local _foo = foo + 1
-+local _bar = bar
+ local foo = foo + 1
+ local bar = bar
 
  -- The variables inside of a repeat...until are accessible from the until statement
  repeat

selene-lib/tests/lints/unused_variable/locals.fixed.diff

@@ -7,8 +7,7 @@
  print(localC)
 
  -- Mutated, but never read
--local localD = 1
-+local _localD = 1
+ local localD = 1
  localD = 2
  localD = 3
 
@@ -29,5 +28,4 @@
 
  -- Put into a table
  local localH = 1
--local localI = { localH }
-+local _localI = { localH }
+ local localI = { localH }

selene-lib/tests/lints/unused_variable/observes.fixed.diff

@@ -1,23 +1,20 @@
--local writtenOnlyA = {}
-+local _writtenOnlyA = {}
+ local writtenOnlyA = {}
  table.insert(writtenOnlyA, 3)
 
  local readA = {}
  print(table.insert(readA, 3))
 
  -- Make sure doing it inside other statements doesn't trigger false negatives
  print(function()
--	local writtenOnlyB = {}
-+	local _writtenOnlyB = {}
+ 	local writtenOnlyB = {}
  	table.insert(writtenOnlyB, 1)
 
  	local readB = {}
  	return table.insert(readB, 1)
  end)
 
  if true then
--	local writtenOnlyC = {}
-+	local _writtenOnlyC = {}
+ 	local writtenOnlyC = {}
  	table.insert(writtenOnlyC, 1)
 
  	local readC = {}

selene-lib/tests/lints/unused_variable/write_only.fixed.diff

@@ -1,5 +1,4 @@
--local bad1 = {}
-+local _bad1 = {}
+ local bad1 = {}
  bad1.x = 1
  bad1.y = 2
  bad1["z"] = 1