Simplify method_exists trait context handling

Replace the complex method_exists special case (checking if each method
name is defined in the trait reflection) with a simple early return when
the object argument depends on the trait context. This trades off not
reporting method_exists($this, 'traitDefinedMethod') as always-true in
trait context, but the check is harmless and this removes 17 lines of
logic. Also make isExpressionDependentOnThis private since it's only
used internally.

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

Author: phpstan-bot

src/Rules/Comparison/ImpossibleCheckTypeHelper.php

@@ -204,22 +204,9 @@ public function findSpecifiedType(
 						$ignoreTraitContext
 						&& $this->isExpressionDependentOnTraitContext($scope, $objectArg)
 					) {
-						$traitReflection = $scope->getTraitReflection();
-						if ($traitReflection === null) {
-							return null;
-						}
-						$methodArgValue = $args[1]->value;
-						$methodArgType = $this->treatPhpDocTypesAsCertain ? $scope->getType($methodArgValue) : $scope->getNativeType($methodArgValue);
-						$constantMethodNames = $methodArgType->getConstantStrings();
-						if (count($constantMethodNames) === 0) {
-							return null;
-						}
-						foreach ($constantMethodNames as $constantMethodName) {
-							if (!$traitReflection->hasNativeMethod($constantMethodName->getValue())) {
-								return null;
-							}
-						}
+						return null;
 					}
+
 					$objectType = $this->treatPhpDocTypesAsCertain ? $scope->getType($objectArg) : $scope->getNativeType($objectArg);
 
 					if ($objectType instanceof ConstantStringType
@@ -419,7 +406,7 @@ private function isExpressionDependentOnTraitContext(Scope $scope, Expr $expr):
 		return false;
 	}
 
-	public static function isExpressionDependentOnThis(Expr $expr): bool
+	private static function isExpressionDependentOnThis(Expr $expr): bool
 	{
 		if ($expr instanceof Expr\Variable && $expr->name === 'this') {
 			return true;

tests/PHPStan/Rules/Comparison/ImpossibleCheckTypeFunctionCallRuleTest.php

@@ -183,10 +183,6 @@ public function testImpossibleCheckTypeFunctionCall(): void
 					'Call to function method_exists() with CheckTypeFunctionCall\MethodExists and \'testWithNewObjectIn…\' will always evaluate to true.',
 					635,
 				],
-				[
-					'Call to function method_exists() with $this(CheckTypeFunctionCall\MethodExistsWithTrait) and \'method\' will always evaluate to true.',
-					650,
-				],
 				[
 					'Call to function method_exists() with \'CheckTypeFunctionCall\\\\MethodExistsWithTrait\' and \'method\' will always evaluate to true.',
 					659,