[Issue 19916] union member access should be un- at safe

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=19916

--- Comment #20 from Manu <turkeyman at gmail.com> ---
> Otherwise, when the focus is on memory corruption, there's more (perceived)
> wiggle room. We're tempted to allow anything that doesn't lead to memory
> corruption in practice, even if has undefined behavior. That quickly gets
> messy.

T x = void; // <- DOES lead to memory corruption; it's effectively an explicit
statement to do memory corruption. How could a more explicit violation of @safe
exist, no matter how you squint and interpret it?


> (In reply to Manu from comment #18)
> > Uninitialised memory is ALREADY CORRUPTED. There is no world where access to
> > what can be confirmed to be uninitialised memory is @safe, period.
> > 
> > Any interaction with uninitialised memory will guarantee unintended
> > consequences, which could be anything.
> > 
> > It's very simple; if you're going to use unions, or uninitialised memory,
> > then do so carefully, and @trusted that block of code.
> 
> You might want to argue your position in
> <https://github.com/dlang/dlang.org/pull/2260>. It's an open PR by Walter
> where he does exactly what you oppose here: he wants to explicitly allow
> accessing uninitialized memory in @safe code (unless it involves pointers).

That PR doesn't appear to have anything to do with @safe?

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