Preserve variable certainty when narrowing the base of a nullsafe operator (#5870)

Co-authored-by: VincentLanglet <9052536+VincentLanglet@users.noreply.github.com>

Author: phpstan-bot

src/Analyser/ExprHandler/Helper/NonNullabilityHelper.php

@@ -70,7 +70,7 @@ public function ensureShallowNonNullability(MutatingScope $scope, Scope $origina
 			$exprToSpecify,
 			$exprTypeWithoutNull,
 			TypeCombinator::removeNull($nativeType),
-			TrinaryLogic::createYes(),
+			$certainty,
 		);
 
 		return new EnsuredNonNullabilityResult(

src/Analyser/NodeScopeResolver.php

@@ -2653,7 +2653,7 @@ private function lookForExpressionCallback(MutatingScope $scope, Expr $expr, Clo
 
 		if ($expr instanceof ArrayDimFetch) {
 			$scope = $this->lookForExpressionCallback($scope, $expr->var, $callback);
-		} elseif ($expr instanceof PropertyFetch || $expr instanceof Expr\NullsafePropertyFetch) {
+		} elseif ($expr instanceof PropertyFetch || $expr instanceof Expr\NullsafePropertyFetch || $expr instanceof Expr\NullsafeMethodCall) {
 			$scope = $this->lookForExpressionCallback($scope, $expr->var, $callback);
 		} elseif ($expr instanceof StaticPropertyFetch && $expr->class instanceof Expr) {
 			$scope = $this->lookForExpressionCallback($scope, $expr->class, $callback);

tests/PHPStan/Rules/Variables/DefinedVariableRuleTest.php

@@ -757,6 +757,33 @@ public function testNullsafeIsset(): void
 		$this->analyse([__DIR__ . '/data/variable-nullsafe-isset.php'], []);
 	}
 
+	#[RequiresPhp('>= 8.0')]
+	public function testBug7291(): void
+	{
+		$this->cliArgumentsVariablesRegistered = true;
+		$this->polluteScopeWithLoopInitialAssignments = false;
+		$this->checkMaybeUndefinedVariables = true;
+		$this->polluteScopeWithAlwaysIterableForeach = true;
+		$this->analyse([__DIR__ . '/data/bug-7291.php'], [
+			[
+				'Variable $a might not be defined.',
+				23,
+			],
+			[
+				'Variable $b might not be defined.',
+				32,
+			],
+			[
+				'Variable $c might not be defined.',
+				41,
+			],
+			[
+				'Variable $d might not be defined.',
+				50,
+			],
+		]);
+	}
+
 	public function testBug1306(): void
 	{
 		$this->cliArgumentsVariablesRegistered = true;

tests/PHPStan/Rules/Variables/data/bug-7291.php

@@ -0,0 +1,96 @@
+<?php // lint >= 8.0
+
+namespace Bug7291;
+
+class Foo
+{
+
+	public ?Foo $foo = null;
+
+	public function bar(): self
+	{
+		return $this;
+	}
+
+}
+
+function bareProp(): void
+{
+	if (rand(0, 1)) {
+		$a = rand(0, 1) ? new Foo() : null;
+	}
+
+	echo $a?->foo; // warn
+}
+
+function bareMethod(): void
+{
+	if (rand(0, 1)) {
+		$b = rand(0, 1) ? new Foo() : null;
+	}
+
+	echo $b?->bar(); // warn
+}
+
+function bareChain(): void
+{
+	if (rand(0, 1)) {
+		$c = rand(0, 1) ? new Foo() : null;
+	}
+
+	echo $c?->bar()?->foo; // warn
+}
+
+function notNullableStillWarns(): void
+{
+	if (rand(0, 1)) {
+		$d = new Foo();
+	}
+
+	echo $d?->foo; // warn
+}
+
+function propCoalesce(): void
+{
+	if (rand(0, 1)) {
+		$e = rand(0, 1) ? new Foo() : null;
+	}
+
+	echo $e?->foo ?? 0; // no warn, ?? handles it
+}
+
+function methodCoalesce(): void
+{
+	if (rand(0, 1)) {
+		$f = rand(0, 1) ? new Foo() : null;
+	}
+
+	echo $f?->bar() ?? 0; // no warn, ?? handles it
+}
+
+function propIsset(): void
+{
+	if (rand(0, 1)) {
+		$g = rand(0, 1) ? new Foo() : null;
+	}
+
+	var_dump(isset($g?->foo)); // no warn, isset handles it
+}
+
+function propEmpty(): void
+{
+	if (rand(0, 1)) {
+		$h = rand(0, 1) ? new Foo() : null;
+	}
+
+	var_dump(empty($h?->foo)); // no warn, empty handles it
+}
+
+function methodEmpty(): void
+{
+	if (rand(0, 1)) {
+		$i = rand(0, 1) ? new Foo() : null;
+	}
+
+	var_dump(empty($i?->bar())); // no warn, empty handles it
+}