on a way of supporting multiple inheritance in Solidity

Question

Question in one sentence:

Regarding function calls, to infer the what the most derived function is, is it enough to track functions in base contracts for each contract, or do we also have to consider the final inheritance graph?

An example below clarifies my question:

contract B {
    function testb() public{ }
}
contract C{
    function testc() public{ }
}

contract D is B,C {
    function testd() public{ }
}

In the above code, are no functions copied into the contract C? Or, should the function testb in contract B be copied into the contract C as the final inheritance graph is D->C->B?

Solidity docs says that:

the code from all the base contracts is copied into the created contract.

Based on the description above, it seems that no functions may be copied into the contract C, as the C has no base contracts.

However, I am still confused because I do not know when we have to consider final inheritance graph. Solidity docs explains only one such case (super call).

Answer 1

Or, should the function testb in contract B be copied into the contract C as the final inheritance graph is D->C->B?

This isn't what your code example shows. D inherits from both C and B, but C doesn't inherit from B. The answer though is that all 3 functions will be present in D, but C & B will only have the functions defined within them.