Description
Services cannot contain constants in method signatures that are defined at runtime. Doing so results in errors during container compilation here and here:

Error: Method ReflectionMethod::__toString() must not throw an exception, caught ErrorException: Warning: Use of undefined constant SOME_CONSTANT - assumed 'SOME_CONSTANT' (this will throw an Error in a future version of PHP)

Is this a (known) limitiation or should this use case be supported?

Background: In Contao we're dealing with some legacy classes that utilize constants in method signatures (see reproducer A). Developers are inheriting from these classes and potentially registering them as services - which fails. Or they might have enabled automatic loading of services (via App\: resource: '../src/*') which had silently worked but suddenly produces a subtle, hard to find error as soon as a class with said method signatures is used. 🤔

How to reproduce (A)

1. Create a class/service Bar that defines a constant at runtime:

class Bar
{
    public function __construct()
    {
        define('SOME_CONSTANT', 1);
    }
}

2. Create a class/service Foo that uses that constant in a method signature: (Inheriting from Bar is optional but would be a typical use case.)

class Foo extends Bar
{
    public function foo($a = SOME_CONSTANT) { 
        // ...
    }
}

3. Build the container.

How to reproduce (B)
In fact the same error will occur for this simplified use case:

1. Create a class/service FooBar

class FooBar
{
    public function __construct()
    {
        define('SOME_CONSTANT', 1);
    }

    public function fooBar($a = SOME_CONSTANT)
    {
    }
}

2. Build the container.