[llvm] [llvm][ELF]Add Shdr check for getBuildID (PR #126537)

[James Henderson via llvm-commits]

jh7370 wrote:

> > Either way, I'm not asking for a huge object when I refer to the "largest valid size". The "valid" size I'm talking about is the size such that it points at the very last byte in a simple ELF object. One past the end is then invalid, because it points outside the file.
> 
> There are already checks in [`ELF.h`](https://github.com/llvm/llvm-project/blob/main/llvm/include/llvm/Object/ELF.h#L405), is it still necessary to implement a test for that?

You're touching on a whole can of worms there, as there are many different testing philosophies that suggest you should or shouldn't have cases that test lower-level function behaviours. For example, if you were to write your tests without knowing what code it uses under the hood, you would write a whole suite of tests that cover various edge cases that might actually end up testing the same cases as are tested elsewhere.

In this case though, I agree it probably makes sense to avoid additional tests for that specific case IF there are already existing tests that cover that behaviour.

https://github.com/llvm/llvm-project/pull/126537