Fix phpstan/phpstan#14311: nullsafe.neverNull false positive when object can be null

- In IssetCheck, the nullsafe.neverNull error was reported unconditionally for
  NullsafePropertyFetch inside ??, isset(), and empty(), without checking if the
  left side of ?-> could actually be null
- Added a check on $expr->var's type before reporting the error, consistent with
  how NullsafePropertyFetchRule already handles this
- Updated test expectations for bug-7109 in NullCoalesceRuleTest, IssetRuleTest,
  and EmptyRuleTest to remove false positive expectations
- New regression test in tests/PHPStan/Rules/Variables/data/bug-14311.php

Author: staabm

src/Rules/IssetCheck.php

@@ -252,6 +252,11 @@ static function (Type $type) use ($typeMessageCallback): ?string {
 		}
 
 		if ($expr instanceof Expr\NullsafePropertyFetch) {
+			$calledOnType = $this->treatPhpDocTypesAsCertain ? $scope->getScopeType($expr->var) : $scope->getScopeNativeType($expr->var);
+			if (!$calledOnType->isNull()->no()) {
+				return null;
+			}
+
 			if ($expr->name instanceof Node\Identifier) {
 				return RuleErrorBuilder::message(sprintf('Using nullsafe property access "?->%s" %s is unnecessary. Use -> instead.', $expr->name->name, $operatorDescription))
 					->identifier('nullsafe.neverNull')

tests/PHPStan/Rules/Variables/EmptyRuleTest.php

@@ -115,30 +115,14 @@ public function testBug7109(): void
 		$this->treatPhpDocTypesAsCertain = true;
 
 		$this->analyse([__DIR__ . '/../Properties/data/bug-7109.php'], [
-			[
-				'Using nullsafe property access "?->aaa" in empty() is unnecessary. Use -> instead.',
-				19,
-			],
-			[
-				'Using nullsafe property access "?->aaa" in empty() is unnecessary. Use -> instead.',
-				30,
-			],
 			[
 				'Using nullsafe property access "?->aaa" in empty() is unnecessary. Use -> instead.',
 				42,
 			],
-			[
-				'Using nullsafe property access "?->notFalsy" in empty() is unnecessary. Use -> instead.',
-				54,
-			],
 			[
 				'Expression in empty() is not falsy.',
 				59,
 			],
-			[
-				'Using nullsafe property access "?->aaa" in empty() is unnecessary. Use -> instead.',
-				68,
-			],
 			[
 				'Using nullsafe property access "?->(Expression)" in empty() is unnecessary. Use -> instead.',
 				75,

tests/PHPStan/Rules/Variables/IssetRuleTest.php

@@ -333,22 +333,10 @@ public function testBug7109(): void
 		$this->treatPhpDocTypesAsCertain = true;
 
 		$this->analyse([__DIR__ . '/../Properties/data/bug-7109.php'], [
-			[
-				'Using nullsafe property access "?->aaa" in isset() is unnecessary. Use -> instead.',
-				18,
-			],
-			[
-				'Using nullsafe property access "?->aaa" in isset() is unnecessary. Use -> instead.',
-				29,
-			],
 			[
 				'Expression in isset() is not nullable.',
 				41,
 			],
-			[
-				'Using nullsafe property access "?->aaa" in isset() is unnecessary. Use -> instead.',
-				67,
-			],
 			[
 				'Expression in isset() is not nullable.',
 				74,

tests/PHPStan/Rules/Variables/NullCoalesceRuleTest.php

@@ -253,22 +253,10 @@ public function testBug5933(): void
 	public function testBug7109(): void
 	{
 		$this->analyse([__DIR__ . '/../Properties/data/bug-7109.php'], [
-			[
-				'Using nullsafe property access "?->aaa" on left side of ?? is unnecessary. Use -> instead.',
-				17,
-			],
-			[
-				'Using nullsafe property access "?->aaa" on left side of ?? is unnecessary. Use -> instead.',
-				28,
-			],
 			[
 				'Expression on left side of ?? is not nullable.',
 				40,
 			],
-			[
-				'Using nullsafe property access "?->aaa" on left side of ?? is unnecessary. Use -> instead.',
-				66,
-			],
 			[
 				'Expression on left side of ?? is not nullable.',
 				73,
@@ -377,4 +365,10 @@ public function testBug13921(): void
 		]);
 	}
 
+	#[RequiresPhp('>= 8.0')]
+	public function testBug14311(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-14311.php'], []);
+	}
+
 }

tests/PHPStan/Rules/Variables/data/bug-14311.php

@@ -0,0 +1,27 @@
+<?php // lint >= 8.0
+
+declare(strict_types = 1);
+
+namespace Bug14311;
+
+class Station {
+	public string $address = '';
+}
+
+/** @param array<string, Station> $stations */
+function withNullCoalesce(array $stations, string $key): string {
+	$bar = $stations[$key] ?? null;
+	return $bar?->address ?? 'Unknown';
+}
+
+/** @param array<string, Station> $stations */
+function withIsset(array $stations, string $key): string {
+	$bar = isset($stations[$key]) ? $stations[$key] : null;
+	return $bar?->address ?? 'Unknown';
+}
+
+/** @param array<string, Station> $stations */
+function withArrayKeyExists(array $stations, string $key): string {
+	$bar = array_key_exists($key, $stations) ? $stations[$key] : null;
+	return $bar?->address ?? 'Unknown';
+}