Report ?-> call on always-null

Author: ondrejmirtes

src/Analyser/NodeScopeResolver.php

@@ -1647,6 +1647,10 @@ private function lookForExpressionCallback(MutatingScope $scope, Expr $expr, Clo
 	private function ensureShallowNonNullability(MutatingScope $scope, Scope $originalScope, Expr $exprToSpecify): EnsuredNonNullabilityResult
 	{
 		$exprType = $scope->getType($exprToSpecify);
+		$isNull = $exprType->isNull();
+		if ($isNull->yes()) {
+			return new EnsuredNonNullabilityResult($scope, []);
+		}
 		$exprTypeWithoutNull = TypeCombinator::removeNull($exprType);
 		if ($exprType->equals($exprTypeWithoutNull)) {
 			$originalExprType = $originalScope->getType($exprToSpecify);

tests/PHPStan/Rules/Methods/CallMethodsRuleTest.php

@@ -1742,6 +1742,14 @@ public function testNullSafe(): void
 				'Parameter #1 $passedByRef of method NullsafeMethodCall\Foo::doBaz() is passed by reference, so it expects variables only.',
 				27,
 			],
+			[
+				'Cannot call method foo() on null.',
+				33,
+			],
+			[
+				'Cannot call method foo() on null.',
+				34,
+			],
 		]);
 	}
 

tests/PHPStan/Rules/Methods/data/nullsafe-method-call.php

@@ -27,4 +27,11 @@ public function doLorem(?self $selfOrNull): void
 		$this->doBaz($selfOrNull?->test->test);
 	}
 
+	public function doNull(): void
+	{
+		$null = null;
+		$null->foo();
+		$null?->foo();
+	}
+
 }

tests/PHPStan/Rules/Properties/AccessPropertiesRuleTest.php

@@ -487,6 +487,14 @@ public function testNullSafe(): void
 				'Cannot access property $bar on string.',
 				22,
 			],
+			[
+				'Cannot access property $foo on null.',
+				28,
+			],
+			[
+				'Cannot access property $foo on null.',
+				29,
+			],
 		]);
 	}
 

tests/PHPStan/Rules/Properties/data/bug-4559.php

@@ -4,9 +4,9 @@
 
 class HelloWorld
 {
-	public function doBar()
+	public function doBar(string $s)
 	{
-		$response = json_decode('');
+		$response = json_decode($s);
 		if (isset($response->error->code)) {
 			echo $response->error->message ?? '';
 		}

tests/PHPStan/Rules/Properties/data/nullsafe-property-fetch.php

@@ -22,4 +22,11 @@ public function doBar(string $string, ?string $nullableString): void
 		echo $nullableString?->bar ?? 4;
 	}
 
+	public function doNull(): void
+	{
+		$null = null;
+		$null->foo;
+		$null?->foo;
+	}
+
 }