fix return type of sprintf with single %s format

src/Type/Php/SprintfFunctionDynamicReturnTypeExtension.php

@@ -21,9 +21,11 @@
 use function array_shift;
 use function count;
 use function in_array;
+use function intval;
 use function is_string;
 use function preg_match;
 use function sprintf;
+use function substr;
 use function vsprintf;
 
 class SprintfFunctionDynamicReturnTypeExtension implements DynamicFunctionReturnTypeExtension
@@ -46,28 +48,49 @@ public function getTypeFromFunctionCall(
 		}
 
 		$formatType = $scope->getType($args[0]->value);
+
 		if (count($formatType->getConstantStrings()) > 0) {
-			$skip = false;
+			$singlePlaceholderEarlyReturn = null;
 			foreach ($formatType->getConstantStrings() as $constantString) {
 				// The printf format is %[argnum$][flags][width][.precision]
-				if (preg_match('/^%([0-9]*\$)?[0-9]*\.?[0-9]*[bdeEfFgGhHouxX]$/', $constantString->getValue(), $matches) === 1) {
-					// invalid positional argument
-					if (array_key_exists(1, $matches) && $matches[1] === '0$') {
+				if (preg_match('/^%([0-9]*\$)?[0-9]*\.?[0-9]*([sbdeEfFgGhHouxX])$/', $constantString->getValue(), $matches) === 1) {
+					if (array_key_exists(1, $matches) && ($matches[1] !== '')) {
+						// invalid positional argument
+						if ($matches[1] === '0$') {
+							return null;
+						}
+						$checkArg = intval(substr($matches[1], 0, -1));
+					} else {
+						$checkArg = 1;
+					}
+
+					// constant string specifies a numbered argument that does not exist
+					if (!array_key_exists($checkArg, $args)) {
 						return null;
 					}
 
+					// if the format string is just a placeholder and specified an argument
+					// of stringy type, then the return value will be of the same type
+					$checkArgType = $scope->getType($args[$checkArg]->value);
+
+					if ($matches[2] === 's' && $checkArgType->isString()->yes()) {
+						$singlePlaceholderEarlyReturn = $checkArgType;
+					} elseif ($matches[2] !== 's') {
+						$singlePlaceholderEarlyReturn = new IntersectionType([
+							new StringType(),
+							new AccessoryNumericStringType(),
+						]);
+					}
+
 					continue;
 				}
 
-				$skip = true;
+				$singlePlaceholderEarlyReturn = null;
 				break;
 			}
 
-			if (!$skip) {
-				return new IntersectionType([
-					new StringType(),
-					new AccessoryNumericStringType(),
-				]);
+			if ($singlePlaceholderEarlyReturn !== null) {
+				return $singlePlaceholderEarlyReturn;
 			}
 		}
 

tests/PHPStan/Analyser/nsrt/bug-11201.php

@@ -0,0 +1,43 @@
+<?php declare(strict_types = 1);
+
+namespace Bug11201;
+
+use function PHPStan\Testing\assertType;
+
+/** @return array<string> */
+function returnsArray(){
+	return [];
+}
+
+/** @return non-empty-string */
+function returnsNonEmptyString(): string
+{
+	return 'a';
+}
+
+/** @return non-falsy-string */
+function returnsNonFalsyString(): string
+{
+	return '1';
+}
+
+/** @return string */
+function returnsJustString(): string
+{
+	return rand(0,1) === 1 ? 'foo' : '';
+}
+
+$s = sprintf("%s", returnsNonEmptyString());
+assertType('non-empty-string', $s);
+
+$s = sprintf("%s", returnsNonFalsyString());
+assertType('non-falsy-string', $s);
+
+$s = sprintf("%s", returnsJustString());
+assertType('string', $s);
+
+$s = sprintf("%s", implode(', ', array_map('intval', returnsArray())));
+assertType('string', $s);
+
+$s = sprintf('%2$s', 1234, returnsNonFalsyString());
+assertType('non-falsy-string', $s);

tests/PHPStan/Analyser/nsrt/bug-7387.php

@@ -61,7 +61,7 @@ public function positionalArgs($mixed, int $i, float $f, string $s) {
 		assertType('numeric-string', sprintf('%2$14F', $mixed, $f));
 		assertType('numeric-string', sprintf('%2$14F', $mixed, $s));
 
-		assertType('numeric-string', sprintf('%10$14F', $mixed, $s));
+		assertType('string', sprintf('%10$14F', $mixed, $s));
 	}
 
 	public function invalidPositionalArgFormat($mixed, string $s) {