Fix module inspect on case insensitive filesystems

[hauleth]

Earlier this outputted error messages when loaded module that existed
with different casing, ex.:

iex> i Datetime

Caused errors to be shown. Now this checks if there is module file
defines module with the same name as the provided atom to prevent such
cases.

Close #8780

[hauleth]

I am not sure how we could test that on case-sensitive systems so there are no tests. If someone have any idea then I am open to it.

[whatyouhide]

@hauleth could we write a test for this that would just do nothing on case-sensitive systems so that at least when the test is running on case-insensitive systems we are testing the correct behaviour?

[hauleth]

@whatyouhide I can write one like that.

[josevalim]

Looks great, just a test and it should be good to go. I don't think the test needs to check for the filesystem because for case sensitive ones we will never show the warning either.

[hauleth]

@josevalim done

[fertapric]

What do you think about using Keyword.fetch to avoid the comment and the default 0 value?

beam_info = :beam_lib.info(beam)

case Keyword.fetch(beam_info, :module) do
  {:ok, ^atom} -> true
  _ -> false
end

[hauleth]

Changed to match?/2.

[josevalim]

This match is equivalent to == {:ok, atom}. -- *José Valimwww.plataformatec.com.br <http://www.plataformatec.com.br/>Founder and Director of R&D*

[hauleth]

@josevalim right, I have missed that.

[whatyouhide]

I would kill this line ✂️

Suggested change

[hauleth]

I personally always separate variables and "main body" of the function, but this is up to you.

[josevalim]

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