Document 43291

[Havvy]

There's yet another footgun in the language right now, as per rust-lang/rust#43291 and so it should be documented if nobody plans on fixing it soon.

[mrhota]

@Havvy it's fixed as of 10 days ago

[nodakai]

I don't think the semantics of int_val as *_ T is clearly documented anywhere, and ironically the "fix" rust-lang/rust#47147 had no impact on the reference!

• https://doc.rust-lang.org/nightly/reference/expressions/operator-expr.html#type-cast-expressions

Integer type | *V where V: Sized | Address to pointer cast

What is the "address to pointer cast" !? Perhaps the original author of this paragraph had LLVM's (zero-extending) inttoptr operation in mind...

• https://llvm.org/docs/LangRef.html#inttoptr-to-instruction

Anyways can we repurpose this ticket for the accurate documentation of casts involving pointers?

[matthewjasper]

Pointer casts are tracked at #66.