UnusedVariableSniff: Fixed false positive

Author: kukulich

SlevomatCodingStandard/Sniffs/Variables/UnusedVariableSniff.php

@@ -453,6 +453,11 @@ private function isUsedInString(File $phpcsFile, int $functionPointer, string $v
 				return true;
 			}
 
+			$variableNameWithoutDollar = substr($variableName, 1);
+			if (preg_match('~\$\{' . preg_quote($variableNameWithoutDollar, '~') . '\}~', $tokens[$stringPointer]['content'])) {
+				return true;
+			}
+
 			$currentPointer = $stringPointer + 1;
 		} while (true);
 

tests/Sniffs/Variables/data/unusedVariableNoErrors.php

@@ -119,13 +119,25 @@ function () {
 	echo "$a";
 };
 
+function () {
+	$a = '';
+	echo "${a}";
+};
+
 function () {
 	$a = '';
 	echo <<<TEXT
 	$a
 TEXT;
 };
 
+function () {
+	$a = '';
+	echo <<<TEXT
+	${a}
+TEXT;
+};
+
 function () {
 	$a = 10;
 	max(1, $a += 10);