UnusedVariableSniff: Fixed false positives

Author: kukulich

SlevomatCodingStandard/Sniffs/Variables/UnusedVariableSniff.php

@@ -30,6 +30,7 @@
 use const T_MOD_EQUAL;
 use const T_MUL_EQUAL;
 use const T_OBJECT_OPERATOR;
+use const T_OPEN_SHORT_ARRAY;
 use const T_OPEN_TAG;
 use const T_OR_EQUAL;
 use const T_PLUS_EQUAL;
@@ -95,6 +96,10 @@ public function process(File $phpcsFile, $variablePointer): void
 			return;
 		}
 
+		if ($this->isUsedAsKeyOrValueInArray($phpcsFile, $variablePointer)) {
+			return;
+		}
+
 		$scopeOwnerPointer = TokenHelper::findPrevious($phpcsFile, T_OPEN_TAG, $variablePointer - 1);
 		foreach (array_reverse($tokens[$variablePointer]['conditions'], true) as $conditionPointer => $conditionTokenCode) {
 			if (in_array($conditionTokenCode, TokenHelper::$functionTokenCodes, true)) {
@@ -316,6 +321,29 @@ private function isUsedInLoop(File $phpcsFile, int $variablePointer, string $var
 		return false;
 	}
 
+	private function isUsedAsKeyOrValueInArray(File $phpcsFile, int $variablePointer): bool
+	{
+		$tokens = $phpcsFile->getTokens();
+
+		$arrayOpenerPointer = TokenHelper::findPrevious($phpcsFile, T_OPEN_SHORT_ARRAY, $variablePointer - 1);
+		if ($arrayOpenerPointer === null) {
+			return false;
+		}
+
+		$arrayCloserPointer = $tokens[$arrayOpenerPointer]['bracket_closer'];
+		if ($arrayCloserPointer < $variablePointer) {
+			return false;
+		}
+
+		$pointerAfterArrayCloser = TokenHelper::findNextEffective($phpcsFile, $arrayCloserPointer + 1);
+		if ($tokens[$pointerAfterArrayCloser]['code'] === T_EQUAL) {
+			return false;
+		}
+
+		$pointerBeforeVariable = TokenHelper::findPreviousEffective($phpcsFile, $variablePointer - 1);
+		return in_array($tokens[$pointerBeforeVariable]['code'], [T_OPEN_SHORT_ARRAY, T_COMMA, T_DOUBLE_ARROW], true);
+	}
+
 	private function isStaticVariable(File $phpcsFile, int $functionPointer, string $variableName): bool
 	{
 		$tokens = $phpcsFile->getTokens();

tests/Sniffs/Variables/data/unusedVariableNoErrors.php

@@ -142,3 +142,12 @@ function () {
 	$a = 10;
 	max(1, $a += 10);
 };
+
+function () {
+	$a = 1;
+	$b = 1;
+	$c = [
+		$b-- => $a++
+	];
+	return $c;
+};