Detect accessing static property on a trait

Author: ondrejmirtes

src/Rules/Properties/AccessStaticPropertiesRule.php

@@ -117,7 +117,18 @@ public function processNode(Node $node, Scope $scope): array
 				} else {
 					$messages = $this->classCaseSensitivityCheck->checkClassNames([new ClassNameNodePair($class, $node->class)]);
 				}
+
+				$classReflection = $this->reflectionProvider->getClass($class);
 				$className = $this->reflectionProvider->getClass($class)->getName();
+				if ($classReflection->isTrait()) {
+					return [
+						RuleErrorBuilder::message(sprintf(
+							'Access to static property $%s on trait %s.',
+							$name,
+							$className
+						))->build(),
+					];
+				}
 			}
 
 			$classType = new ObjectType($className);

tests/PHPStan/Rules/Properties/AccessStaticPropertiesRuleTest.php

@@ -167,6 +167,14 @@ public function testAccessStaticProperties(): void
 				'Access to an undefined static property AccessInIsset::$foo.',
 				185,
 			],
+			[
+				'Access to static property $foo on trait TraitWithStaticProperty.',
+				204,
+			],
+			[
+				'Access to static property $foo on an unknown class TraitWithStaticProperty.',
+				209,
+			],
 		]);
 	}
 

tests/PHPStan/Rules/Properties/data/access-static-properties.php

@@ -188,3 +188,25 @@ public function doBar()
 	}
 
 }
+
+trait TraitWithStaticProperty
+{
+
+	public static $foo;
+
+}
+
+class MethodAccessingTraitProperty
+{
+
+	public function doFoo(): void
+	{
+		echo TraitWithStaticProperty::$foo;
+	}
+
+	public function doBar(TraitWithStaticProperty $a): void
+	{
+		echo $a::$foo;
+	}
+
+}