Add tests for MethodCallReturnTypeHelper fallback on static calls

Tests the generic fallback logic in MethodCallReturnTypeHelper for
static method calls on union types where only some classes are handled
by dynamic return type extensions. Uses BackedEnum::from() as the
extension-handled case and a plain class as the unhandled fallback case.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: phpstan-bot

tests/PHPStan/Analyser/nsrt/method-call-return-type-fallback.php

@@ -0,0 +1,27 @@
+<?php // lint >= 8.1
+
+namespace MethodCallReturnTypeFallback;
+
+use function PHPStan\Testing\assertType;
+
+enum Suit: string {
+	case Hearts = 'hearts';
+	case Diamonds = 'diamonds';
+}
+
+class MyClass {
+	/** @return self */
+	public static function from(string $value): self {
+		return new self();
+	}
+}
+
+/** @param class-string<Suit>|class-string<MyClass> $class */
+function testStaticCallOnUnionWithConstant(string $class): void {
+	assertType('MethodCallReturnTypeFallback\MyClass|MethodCallReturnTypeFallback\Suit::Hearts', $class::from('hearts'));
+}
+
+/** @param class-string<Suit>|class-string<MyClass> $class */
+function testStaticCallOnUnionWithVariable(string $class, string $value): void {
+	assertType('MethodCallReturnTypeFallback\MyClass|MethodCallReturnTypeFallback\Suit', $class::from($value));
+}