Support @mixin above traits

Author: ondrejmirtes

src/Reflection/Mixin/MixinMethodsClassReflectionExtension.php

@@ -74,6 +74,15 @@ private function findMethod(ClassReflection $classReflection, string $methodName
 			return new MixinMethodReflection($method, $static);
 		}
 
+		foreach ($classReflection->getTraits() as $traitClass) {
+			$methodWithDeclaringClass = $this->findMethod($traitClass, $methodName);
+			if ($methodWithDeclaringClass === null) {
+				continue;
+			}
+
+			return $methodWithDeclaringClass;
+		}
+
 		$parentClass = $classReflection->getParentClass();
 		while ($parentClass !== null) {
 			$method = $this->findMethod($parentClass, $methodName);

src/Reflection/Mixin/MixinPropertiesClassReflectionExtension.php

@@ -65,6 +65,15 @@ private function findProperty(ClassReflection $classReflection, string $property
 			return $property;
 		}
 
+		foreach ($classReflection->getTraits() as $traitClass) {
+			$methodWithDeclaringClass = $this->findProperty($traitClass, $propertyName);
+			if ($methodWithDeclaringClass === null) {
+				continue;
+			}
+
+			return $methodWithDeclaringClass;
+		}
+
 		$parentClass = $classReflection->getParentClass();
 		while ($parentClass !== null) {
 			$property = $this->findProperty($parentClass, $propertyName);

tests/PHPStan/Analyser/NodeScopeResolverTest.php

@@ -114,6 +114,8 @@ public function dataFileAsserts(): iterable
 		yield from $this->gatherAssertTypes(__DIR__ . '/../Rules/Methods/data/conditional-complex-templates.php');
 
 		yield from $this->gatherAssertTypes(__DIR__ . '/../Rules/Methods/data/bug-7511.php');
+		yield from $this->gatherAssertTypes(__DIR__ . '/../Rules/Properties/data/trait-mixin.php');
+		yield from $this->gatherAssertTypes(__DIR__ . '/../Rules/Methods/data/trait-mixin.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/../Rules/Comparison/data/bug-4708.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/../Rules/Functions/data/bug-7156.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/../Rules/Arrays/data/bug-6364.php');

tests/PHPStan/Rules/Methods/CallMethodsRuleTest.php

@@ -3345,4 +3345,13 @@ public function testNoNamedArguments(): void
 		]);
 	}
 
+	public function testTraitMixin(): void
+	{
+		$this->checkThisOnly = false;
+		$this->checkNullables = true;
+		$this->checkUnionTypes = true;
+		$this->checkExplicitMixed = true;
+		$this->analyse([__DIR__ . '/data/trait-mixin.php'], []);
+	}
+
 }

tests/PHPStan/Rules/Methods/data/trait-mixin.php

@@ -0,0 +1,44 @@
+<?php
+
+namespace TraitMixinMethods;
+
+use function PHPStan\Testing\assertType;
+
+/**
+ * @template T
+ */
+interface Foo
+{
+
+	/** @return T */
+	public function get();
+
+}
+
+/**
+ * @mixin Foo<static>
+ */
+trait FooTrait
+{
+
+}
+
+class Usages
+{
+
+	use FooTrait;
+
+}
+
+class ChildUsages extends Usages
+{
+
+}
+
+function (Usages $u): void {
+	assertType(Usages::class, $u->get());
+};
+
+function (ChildUsages $u): void {
+	assertType(ChildUsages::class, $u->get());
+};

tests/PHPStan/Rules/Properties/AccessPropertiesRuleTest.php

@@ -949,4 +949,12 @@ public function testBug9694(): void
 		$this->analyse([__DIR__ . '/data/bug-9694.php'], []);
 	}
 
+	public function testTraitMixin(): void
+	{
+		$this->checkThisOnly = false;
+		$this->checkUnionTypes = true;
+		$this->checkDynamicProperties = true;
+		$this->analyse([__DIR__ . '/data/trait-mixin.php'], []);
+	}
+
 }

tests/PHPStan/Rules/Properties/data/trait-mixin.php

@@ -0,0 +1,45 @@
+<?php
+
+namespace TraitMixinProperties;
+
+use function PHPStan\Testing\assertType;
+
+/**
+ * @template T
+ */
+class Foo
+{
+
+	/** @var T */
+	public $a;
+
+}
+
+/**
+ * @mixin Foo<static>
+ */
+trait FooTrait
+{
+
+}
+
+#[\AllowDynamicProperties]
+class Usages
+{
+
+	use FooTrait;
+
+}
+
+class ChildUsages extends Usages
+{
+
+}
+
+function (Usages $u): void {
+	assertType(Usages::class, $u->a);
+};
+
+function (ChildUsages $u): void {
+	assertType(ChildUsages::class, $u->a);
+};