support positional arguments in sprintf() constant format inference

Author: staabm

src/Type/Php/SprintfFunctionDynamicReturnTypeExtension.php

@@ -15,6 +15,7 @@
 use PHPStan\Type\StringType;
 use PHPStan\Type\Type;
 use Throwable;
+use function array_key_exists;
 use function array_shift;
 use function count;
 use function is_string;
@@ -33,7 +34,7 @@ public function getTypeFromFunctionCall(
 FunctionReflection $functionReflection,
 FuncCall $functionCall,
 Scope $scope,
-): Type
+): ?Type
 {
 $args = $functionCall->getArgs();
 if (count($args) === 0) {
@@ -43,7 +44,13 @@ public function getTypeFromFunctionCall(
 $formatType = $scope->getType($args[0]->value);
 
 if ($formatType instanceof ConstantStringType) {
-if (preg_match('/^%[0-9]*\.?[0-9]+[bdeEfFgGhHouxX]$/', $formatType->getValue()) === 1) {
+// The printf format is %[argnum$][flags][width][.precision]
+if (preg_match('/^%([0-9]*\$)?[0-9]*\.?[0-9]+[bdeEfFgGhHouxX]$/', $formatType->getValue(), $matches) === 1) {
+// invalid positional argument
+if (array_key_exists(1, $matches) && $matches[1] === '0$') {
+return null;
+}
+
 return new IntersectionType([
 new StringType(),
 new AccessoryNumericStringType(),

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

@@ -42,4 +42,27 @@ public function specifiers(int $i) {
 assertType('numeric-string', sprintf('%14X', $i));
 
 }
+
+public function positionalArgs($mixed, int $i, float $f, string $s) {
+// https://3v4l.org/vVL0c
+assertType('non-empty-string', sprintf('%2$14s', $mixed, $i));
+
+assertType('numeric-string', sprintf('%2$.14F', $mixed, $i));
+assertType('numeric-string', sprintf('%2$.14F', $mixed, $f));
+assertType('numeric-string', sprintf('%2$.14F', $mixed, $s));
+
+assertType('numeric-string', sprintf('%2$1.14F', $mixed, $i));
+assertType('numeric-string', sprintf('%2$2.14F', $mixed, $f));
+assertType('numeric-string', sprintf('%2$3.14F', $mixed, $s));
+
+assertType('numeric-string', sprintf('%2$14F', $mixed, $i));
+assertType('numeric-string', sprintf('%2$14F', $mixed, $f));
+assertType('numeric-string', sprintf('%2$14F', $mixed, $s));
+
+assertType('numeric-string', sprintf('%10$14F', $mixed, $s));
+}
+
+public function invalidPositionalArgFormat($mixed, string $s) {
+assertType('string', sprintf('%0$14F', $mixed, $s));
+}
 }