accessing private fields is not safe, and io isn't scary

[Gankra]

Quick poll of basically the entire core team says this is ok.

[rust-highfive]

r? @huonw

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[steveklabnik]

@bors: r+ rollup

[bors]

📌 Commit 9001da6 has been approved by steveklabnik

[bluss]

How does this interact with what it says 18 lines previously?

[Behavior considered undefined] Invalid values in primitive types, even in private fields/locals

Is it now ok in private fields, since private fields are not permitted to be read?

[Gankra]

I think it's fine to make a private mem::uninitialized as long as a public consumer can't observe it. Making a bool = 3 is still invalid, though.

[huonw]

What's the difference between a private field bool = 3, and the same field being mem::uninitialized? Presumably it's essentially illegal to read such a thing in both cases, but they should be fine to be "write only".

[bluss]

I think I answered my own question why it's not a good idea to allow (see forum).