Treat * as assignment suppression in sscanf/fscanf placeholder counting

src/Rules/Functions/PrintfHelper.php

@@ -26,24 +26,24 @@ public function __construct(private PhpVersion $phpVersion)
 
 	public function getPrintfPlaceholdersCount(string $format): ?int
 	{
-		return $this->getPlaceholdersCount(self::PRINTF_SPECIFIER_PATTERN, $format);
+		return $this->getPlaceholdersCount(self::PRINTF_SPECIFIER_PATTERN, $format, false);
 	}
 
 	/** @phpstan-return array<int, non-empty-list<PrintfPlaceholder>> parameter index => placeholders */
 	public function getPrintfPlaceholders(string $format): ?array
 	{
-		return $this->parsePlaceholders(self::PRINTF_SPECIFIER_PATTERN, $format);
+		return $this->parsePlaceholders(self::PRINTF_SPECIFIER_PATTERN, $format, false);
 	}
 
 	public function getScanfPlaceholdersCount(string $format): ?int
 	{
-		return $this->getPlaceholdersCount('(?<specifier>[cdDeEfinosuxX%s]|\[[^\]]+\])', $format);
+		return $this->getPlaceholdersCount('(?<specifier>[cdDeEfinosuxX%s]|\[[^\]]+\])', $format, true);
 	}
 
 	/**
 	 * @phpstan-return array<int, non-empty-list<PrintfPlaceholder>>|null parameter index => placeholders
 	 */
-	private function parsePlaceholders(string $specifiersPattern, string $format): ?array
+	private function parsePlaceholders(string $specifiersPattern, string $format, bool $isScanf): ?array
 	{
 		$addSpecifier = '';
 		if ($this->phpVersion->supportsHhPrintfSpecifier()) {
@@ -72,6 +72,10 @@ private function parsePlaceholders(string $specifiersPattern, string $format): ?
 			$showValueSuffix = false;
 
 			if (isset($placeholder['width']) && $placeholder['width'] !== '') {
+				if ($isScanf) {
+					// In scanf, * means assignment suppression - skip this placeholder entirely
+					continue;
+				}
 				$parsedPlaceholders[] = new PrintfPlaceholder(
 					sprintf('"%s" (width)', $placeholder[0]),
 					$parameterIdx++,
@@ -132,9 +136,9 @@ private function getAcceptingTypeBySpecifier(string $specifier): string
 		return 'mixed';
 	}
 
-	private function getPlaceholdersCount(string $specifiersPattern, string $format): ?int
+	private function getPlaceholdersCount(string $specifiersPattern, string $format, bool $isScanf): ?int
 	{
-		$placeholdersMap = $this->parsePlaceholders($specifiersPattern, $format);
+		$placeholdersMap = $this->parsePlaceholders($specifiersPattern, $format, $isScanf);
 		if ($placeholdersMap === null) {
 			return null;
 		}

tests/PHPStan/Analyser/nsrt/sscanf.php

@@ -48,3 +48,10 @@ function fooo(string $s) {
 
 	assertType('array{int|null, int|null, int|null}|null', sscanf('00ccff', '%2x%2x%2x'));
 }
+
+function sscanfSuppression(string $s) {
+	// %* means assignment suppression - these should not appear in return array
+	assertType('array{int|null}|null', sscanf($s, '%*s %d'));
+	assertType('array{string|null}|null', sscanf($s, '%*d %s'));
+	assertType('array{int|null}|null', sscanf($s, '%*[a-z]%d'));
+}

tests/PHPStan/Rules/Functions/PrintfParametersRuleTest.php

@@ -142,4 +142,9 @@ public function testBug8774(): void
 		$this->analyse([__DIR__ . '/data/bug-8774.php'], []);
 	}
 
+	public function testBug10260(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-10260.php'], []);
+	}
+
 }

tests/PHPStan/Rules/Functions/data/bug-10260.php

@@ -0,0 +1,27 @@
+<?php
+
+namespace Bug10260;
+
+// %* in scanf means "assignment suppression" - match but don't store
+// These should NOT count as placeholders
+
+// From the issue: %*[a-z] matches lowercase letters but doesn't assign
+sscanf('appletone_day_1', '%*[a-z]_day_%s', $day_number);
+
+// %*d means match an integer but don't assign it
+sscanf('123 456', '%*d %d', $number);
+
+// Multiple suppressed placeholders
+sscanf('foo 123 bar', '%*s %*d %s', $str);
+
+// Suppressed with character class
+sscanf('ABC123', '%*[A-Z]%d', $num);
+
+// Mix of suppressed and non-suppressed
+sscanf('hello world 42', '%s %*s %d', $word, $num2);
+
+// fscanf with suppression
+fscanf(STDIN, '%*d %s', $value);
+
+// No values needed when all are suppressed (returned as array)
+sscanf('123 abc', '%*d %*s');