Class constants cannot be directly accessed on a trait

Author: ondrejmirtes

src/Rules/Classes/ClassConstantRule.php

@@ -111,9 +111,24 @@ public function processNode(Node $node, Scope $scope): array
 					];
 				}
 
-				$messages = $this->classCheck->checkClassNames([new ClassNameNodePair($className, $class)]);
-
 				$classType = $scope->resolveTypeByName($class);
+				if (strtolower($constantName) !== 'class') {
+					foreach ($classType->getObjectClassReflections() as $classTypeReflection) {
+						if (!$classTypeReflection->isTrait()) {
+							continue;
+						}
+
+						return [
+							RuleErrorBuilder::message(sprintf(
+								'Cannot access constant %s on trait %s.',
+								$constantName,
+								$classTypeReflection->getDisplayName(),
+							))->identifier('classConstant.onTrait')->build(),
+						];
+					}
+				}
+
+				$messages = $this->classCheck->checkClassNames([new ClassNameNodePair($className, $class)]);
 			}
 
 			if (strtolower($constantName) === 'class') {

tests/PHPStan/Rules/Classes/ClassConstantRuleTest.php

@@ -420,4 +420,19 @@ public function testPhpstanInternalClass(): void
 		]);
 	}
 
+	public function testClassConstantAccessedOnTrait(): void
+	{
+		if (PHP_VERSION_ID < 80200) {
+			$this->markTestSkipped('Test requires PHP 8.2.');
+		}
+
+		$this->phpVersion = PHP_VERSION_ID;
+		$this->analyse([__DIR__ . '/data/class-constant-accessed-on-trait.php'], [
+			[
+				'Cannot access constant TEST on trait ClassConstantAccessedOnTrait\Foo.',
+				16,
+			],
+		]);
+	}
+
 }

tests/PHPStan/Rules/Classes/data/class-constant-accessed-on-trait.php

@@ -0,0 +1,18 @@
+<?php // lint >= 8.2
+
+namespace ClassConstantAccessedOnTrait;
+
+trait Foo
+{
+	public const TEST = 1;
+}
+
+class Bar
+{
+	use Foo;
+}
+
+function (): void {
+	echo Foo::TEST;
+	echo Foo::class;
+};