bjorn3

> but I guess mapping discriminants to variant idxes is not guaranteed to be 1-1, is there anyway to check that? I believe ```rust enum Foo { Bar = 2,...

> Where does one create or acquire HCX (I assume that's hashing context). Using either `tcx.create_stable_hashing_context` or `tcx.create_no_span_stable_hashing_context`. The `TyCtxt` type is not available in `rustc_data_structure`, so the hashing context...

You are probably looking for https://github.com/rust-lang/rust/blob/master/compiler/rustc_middle/src/query/mod.rs

Iteration order for `FxHashSet` is only dependent on the exact set of operations performed on it. There is no randomness introduced. Serializing an `FxHashSet` in iteration order into the crate...

Looks like we do for `Interned`.

> Implement a custom version of HashStable for pointer-like objects such as Interned, as it's recursive, it might fix the problems we have instead of a wrapper. `HashStable` is completely...

> Does that make sense? Yes!

I'm surprised this wasn't already added. > For instance, adding it by default gets us closer to other popular compilers, but that may surprise some users with an information leak....

It is quite useful for easily figuring out which rustc version an executable was built with. This could for example be used to determine that it needs to be rebuilt...

I don't have permission to start an fcp. Also should this be a compiler or lang team fcp?