Are there any general-purpose programming languages with classes, objects, methods, interfaces, and so on, which disallow class-based inheritance?
This reads very much like a description of VBA - Visual Basic for Applications, embedded in Microsoft Office and other VBA-enabled hosts (e.g. AutoCAD, Sage 300 ERP, etc.), or even VB6. The "A" of "Basic" stands for "All-purpose" anyway, so there's the "general-purpose" part.
VB6/VBA has classes (and therefore objects), methods and interfaces - you could define an
ISomething interface in a class module like this:
Option Explicit Public Sub DoSomething() End Sub
And then have another class that does this:
Option Explicit Implements ISomething Private Sub ISomething_DoSomething() 'implementation here End Sub
Such a class, exposing no public members, could only ever be accessed via its
ISomething interface - and there could very well be dozens of different implementations of
ISomething out there, so OOP VBA code is perfectly capable of polymorphism, and it's perfectly legal for a given class to implement multiple interfaces, too.
VB6/VBA does not allow class inheritance however, so you can't inherit an implementation from another type, only its interface. Now, whether this is an accident, a design flaw, a stroke of genius or a huge ugly oversight is open for debate; it's not clear whether VB6/VBA takes this to heart, but it most definitely enforces it.
If Go doesn't do class inheritance and is nonetheless an OOP languageGo doesn't do class inheritance and is nonetheless an OOP language, then I don't see why VB6/VBA couldn't be considered an OOP language as well.