Incorrect "operation requires unsafe block"

[RalfJung]

When using rust-analyzer with the standard library, it shows an error for this code in sore/src/ptr/const_ptr.rs:

    pub const fn guaranteed_eq(self, other: *const T) -> bool
    where
        T: Sized,
    {
        intrinsics::ptr_guaranteed_eq(self, other)
    }

It says this needs an unsafe block, but it evidently does not as the code compiles fine. Indeed, ptr_guaranteed_eq is a safe intrinsic.

[bjorn3]

rust-analyzer doesn't have a list of safe intrinsics. It just assumes that all are unsafe.

[RalfJung]

Yeah, I figured. That assumption is incorrect, though.

[matklad]

We need to figure out how rustc distinguish between safe and unsafe intrinsics and do the same.

[RalfJung]

rustc essentially has a whitelist of safe intrinsics, the rest is unsafe:

https://github.com/rust-lang/rust/blob/c6e4db620a7d2f569f11dcab627430921ea8aacf/compiler/rustc_typeck/src/check/intrinsic.rs#L68

[matklad]

Ok, I think we need then to hack this around here:

https://github.com/rust-analyzer/rust-analyzer/blob/7dd09a7b34d7c9cc2739a1106b3e383b7d9044ff/crates/hir_def/src/item_tree/lower.rs#L558

We need to check that we are in extern "rust-intrinsics" block syntatically, and then look at he names