In a language that supports multiple inheritance, what type of problem is faced in "diamond problem"?

The "diamond problem" is a common issue in programming languages that support multiple inheritance. This problem occurs when a class inherits from two or more classes that have a common base class. Here's a step-by-step explanation:

1. Let's say we have a class structure where class A is the base class, and classes B and C are derived from A. Now, class D is derived from both B and C.

2. Class A has a method named 'foo'. Both B and C have overridden this method.

3. Now, when the method 'foo' is called on an object of class D, the compiler gets confused. It doesn't know whether to execute the 'foo' method from class B or class C. This ambiguity is known as the diamond problem.

4. Some languages like C++ allow the programmer to specify which method to use in such scenarios. Other languages like Java avoid this problem by not supporting multiple inheritance.

5. The diamond problem is a significant issue because it can lead to unexpected results and bugs that are hard to track down. It's one of the reasons why some languages choose to support only single inheritance or use other mechanisms like interfaces or mixins.