Use rtrim() semantics for chop() on constant strings (#7012)

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

Author: SanderMuller

src/Type/Php/TrimFunctionDynamicReturnTypeExtension.php

@@ -71,7 +71,7 @@ public function getTypeFromFunctionCall(
 				if (count($stringConstantStrings) > 0) {
 					foreach ($stringConstantStrings as $stringConstantString) {
 						$result[] = new ConstantStringType(
-							$functionName === 'rtrim'
+							in_array($functionName, ['rtrim', 'chop'], true)
 								? rtrim($stringConstantString->getValue(), $trimConstantString->getValue())
 								: trim($stringConstantString->getValue(), $trimConstantString->getValue()),
 							true,

tests/PHPStan/Analyser/nsrt/bug-15684.php

@@ -0,0 +1,13 @@
+<?php declare(strict_types = 1);
+
+namespace Bug15684;
+
+use function PHPStan\Testing\assertType;
+
+function doFoo(): void
+{
+	assertType("' a'", chop(' a ', ' '));
+	assertType("'yax'", chop('yax', 'y'));
+	assertType("' a'", rtrim(' a ', ' '));
+	assertType('true', chop(' a ', ' ') === ' a');
+}