Rollup merge of #152019 - nnethercote:rm-unneeded-HashStable-derives, r=Zalathar

`NativeLib` cleanups

Improvements to `NativeLib`.

r? @Zalathar

Author: JonathanBrouwer

Cargo.lock

@@ -3683,7 +3683,6 @@ dependencies = [
  "rustc_macros",
  "rustc_metadata",
  "rustc_middle",
- "rustc_query_system",
  "rustc_serialize",
  "rustc_session",
  "rustc_span",

compiler/rustc_codegen_ssa/Cargo.toml

@@ -28,7 +28,6 @@ rustc_lint_defs = { path = "../rustc_lint_defs" }
 rustc_macros = { path = "../rustc_macros" }
 rustc_metadata = { path = "../rustc_metadata" }
 rustc_middle = { path = "../rustc_middle" }
-rustc_query_system = { path = "../rustc_query_system" }
 rustc_serialize = { path = "../rustc_serialize" }
 rustc_session = { path = "../rustc_session" }
 rustc_span = { path = "../rustc_span" }

compiler/rustc_codegen_ssa/src/lib.rs

@@ -24,7 +24,7 @@ use rustc_data_structures::unord::UnordMap;
 use rustc_hir::CRATE_HIR_ID;
 use rustc_hir::attrs::{CfgEntry, NativeLibKind, WindowsSubsystemKind};
 use rustc_hir::def_id::CrateNum;
-use rustc_macros::{Decodable, Encodable, HashStable};
+use rustc_macros::{Decodable, Encodable};
 use rustc_metadata::EncodedMetadata;
 use rustc_middle::dep_graph::WorkProduct;
 use rustc_middle::lint::LevelAndSource;
@@ -175,7 +175,12 @@ bitflags::bitflags! {
     }
 }
 
-#[derive(Clone, Debug, Encodable, Decodable, HashStable)]
+// This is the same as `rustc_session::cstore::NativeLib`, except:
+// - (important) the `foreign_module` field is missing, because it contains a `DefId`, which can't
+//   be encoded with `FileEncoder`.
+// - (less important) the `verbatim` field is a `bool` rather than an `Option<bool>`, because here
+//   we can treat `false` and `absent` the same.
+#[derive(Clone, Debug, Encodable, Decodable)]
 pub struct NativeLib {
     pub kind: NativeLibKind,
     pub name: Symbol,