Fix phpstan/phpstan#10786: Invalid return type definition

src/Analyser/MutatingScope.php

@@ -1068,15 +1068,20 @@ public function issetCheck(Expr $expr, callable $typeCallback, ?bool $result = n
 
 			if ($propertyReflection->hasNativeType() && !$propertyReflection->isVirtual()->yes()) {
 				if (!$this->hasExpressionType($expr)->yes()) {
-					if ($expr instanceof Node\Expr\PropertyFetch) {
-						return $this->issetCheckUndefined($expr->var);
-					}
+					if ($propertyReflection->getWritableType()->isNull()->no()) {
+						if ($expr instanceof Node\Expr\PropertyFetch) {
+							return $this->issetCheckUndefined($expr->var);
+						}
 
-					if ($expr->class instanceof Expr) {
-						return $this->issetCheckUndefined($expr->class);
+						if ($expr->class instanceof Expr) {
+							return $this->issetCheckUndefined($expr->class);
+						}
+
+						return null;
 					}
 
-					return null;
+					// Nullable native property: fall through to type callback
+					// so that isset() falsey properly narrows to null
 				}
 			}
 

src/Analyser/TypeSpecifier.php

@@ -1917,10 +1917,7 @@ private function processBooleanSureConditionalTypes(Scope $scope, SpecifiedTypes
 	{
 		$conditionExpressionTypes = [];
 		foreach ($leftTypes->getSureTypes() as $exprString => [$expr, $type]) {
-			if (!$expr instanceof Expr\Variable) {
-				continue;
-			}
-			if (!is_string($expr->name)) {
+			if (!$this->canBeConditionalExpressionHolder($expr)) {
 				continue;
 			}
 
@@ -1933,10 +1930,7 @@ private function processBooleanSureConditionalTypes(Scope $scope, SpecifiedTypes
 		if (count($conditionExpressionTypes) > 0) {
 			$holders = [];
 			foreach ($rightTypes->getSureTypes() as $exprString => [$expr, $type]) {
-				if (!$expr instanceof Expr\Variable) {
-					continue;
-				}
-				if (!is_string($expr->name)) {
+				if (!$this->canBeConditionalExpressionHolder($expr)) {
 					continue;
 				}
 
@@ -1945,20 +1939,7 @@ private function processBooleanSureConditionalTypes(Scope $scope, SpecifiedTypes
 				}
 
 				$conditions = $conditionExpressionTypes;
-				foreach ($conditions as $conditionExprString => $conditionExprTypeHolder) {
-					$conditionExpr = $conditionExprTypeHolder->getExpr();
-					if (!$conditionExpr instanceof Expr\Variable) {
-						continue;
-					}
-					if (!is_string($conditionExpr->name)) {
-						continue;
-					}
-					if ($conditionExpr->name !== $expr->name) {
-						continue;
-					}
-
-					unset($conditions[$conditionExprString]);
-				}
+				unset($conditions[$exprString]);
 
 				if (count($conditions) === 0) {
 					continue;
@@ -2038,10 +2019,7 @@ private function processBooleanNotSureConditionalTypes(Scope $scope, SpecifiedTy
 	{
 		$conditionExpressionTypes = [];
 		foreach ($leftTypes->getSureNotTypes() as $exprString => [$expr, $type]) {
-			if (!$expr instanceof Expr\Variable) {
-				continue;
-			}
-			if (!is_string($expr->name)) {
+			if (!$this->canBeConditionalExpressionHolder($expr)) {
 				continue;
 			}
 
@@ -2054,10 +2032,7 @@ private function processBooleanNotSureConditionalTypes(Scope $scope, SpecifiedTy
 		if (count($conditionExpressionTypes) > 0) {
 			$holders = [];
 			foreach ($rightTypes->getSureNotTypes() as $exprString => [$expr, $type]) {
-				if (!$expr instanceof Expr\Variable) {
-					continue;
-				}
-				if (!is_string($expr->name)) {
+				if (!$this->canBeConditionalExpressionHolder($expr)) {
 					continue;
 				}
 
@@ -2066,20 +2041,7 @@ private function processBooleanNotSureConditionalTypes(Scope $scope, SpecifiedTy
 				}
 
 				$conditions = $conditionExpressionTypes;
-				foreach ($conditions as $conditionExprString => $conditionExprTypeHolder) {
-					$conditionExpr = $conditionExprTypeHolder->getExpr();
-					if (!$conditionExpr instanceof Expr\Variable) {
-						continue;
-					}
-					if (!is_string($conditionExpr->name)) {
-						continue;
-					}
-					if ($conditionExpr->name !== $expr->name) {
-						continue;
-					}
-
-					unset($conditions[$conditionExprString]);
-				}
+				unset($conditions[$exprString]);
 
 				if (count($conditions) === 0) {
 					continue;
@@ -2098,6 +2060,14 @@ private function processBooleanNotSureConditionalTypes(Scope $scope, SpecifiedTy
 		return [];
 	}
 
+	private function canBeConditionalExpressionHolder(Expr $expr): bool
+	{
+		return $expr instanceof Expr\Variable
+			|| $expr instanceof Expr\PropertyFetch
+			|| $expr instanceof Expr\StaticPropertyFetch
+			|| $expr instanceof Expr\ArrayDimFetch;
+	}
+
 	/**
 	 * @return array{Expr, ConstantScalarType, Type}|null
 	 */

tests/PHPStan/Analyser/nsrt/bug-10786.php

@@ -0,0 +1,36 @@
+<?php declare(strict_types = 1);
+
+namespace Bug10786;
+
+use function PHPStan\Testing\assertType;
+
+class Value {
+	public ?int $value = null;
+}
+
+class HelloWorld
+{
+	public function sayHello(Value $a, Value $b): int
+	{
+		if (is_null($a->value) && is_null($b->value)) {
+			throw new \Exception();
+		}
+
+		assertType('int', $a->value ?? $b->value);
+
+		return $a->value ?? $b->value;
+	}
+
+	public function sayHello2(Value $a, Value $b): int
+	{
+		if ($a->value === null && $b->value === null) {
+			throw new \Exception();
+		}
+
+		assertType('int|null', $a->value);
+		assertType('int|null', $b->value);
+		assertType('int', $a->value ?? $b->value);
+
+		return $a->value ?? $b->value;
+	}
+}