From 11fbb573951d61b7de9b773750c206253a5db974 Mon Sep 17 00:00:00 2001
From: Camille GILLOT <gillot.camille@gmail.com>
Date: Tue, 25 Oct 2022 18:34:58 +0000
Subject: [PATCH] Simplify diagnostic_items.

---
 compiler/rustc_middle/src/hir/mod.rs          | 14 +++--
 compiler/rustc_passes/src/diagnostic_items.rs | 63 +++++++++----------
 2 files changed, 39 insertions(+), 38 deletions(-)

diff --git a/compiler/rustc_middle/src/hir/mod.rs b/compiler/rustc_middle/src/hir/mod.rs
index 2e2ca6a2788..ad119c4e073 100644
--- a/compiler/rustc_middle/src/hir/mod.rs
+++ b/compiler/rustc_middle/src/hir/mod.rs
@@ -64,13 +64,17 @@ pub fn foreign_items(&self) -> impl Iterator<Item = ForeignItemId> + '_ {
         self.foreign_items.iter().copied()
     }
 
-    pub fn definitions(&self) -> impl Iterator<Item = LocalDefId> + '_ {
+    pub fn owners(&self) -> impl Iterator<Item = OwnerId> + '_ {
         self.items
             .iter()
-            .map(|id| id.owner_id.def_id)
-            .chain(self.trait_items.iter().map(|id| id.owner_id.def_id))
-            .chain(self.impl_items.iter().map(|id| id.owner_id.def_id))
-            .chain(self.foreign_items.iter().map(|id| id.owner_id.def_id))
+            .map(|id| id.owner_id)
+            .chain(self.trait_items.iter().map(|id| id.owner_id))
+            .chain(self.impl_items.iter().map(|id| id.owner_id))
+            .chain(self.foreign_items.iter().map(|id| id.owner_id))
+    }
+
+    pub fn definitions(&self) -> impl Iterator<Item = LocalDefId> + '_ {
+        self.owners().map(|id| id.def_id)
     }
 
     pub fn par_items(&self, f: impl Fn(ItemId) + Send + Sync) {
diff --git a/compiler/rustc_passes/src/diagnostic_items.rs b/compiler/rustc_passes/src/diagnostic_items.rs
index 0ae7096642c..ae3d40b0ec5 100644
--- a/compiler/rustc_passes/src/diagnostic_items.rs
+++ b/compiler/rustc_passes/src/diagnostic_items.rs
@@ -11,19 +11,19 @@
 
 use rustc_ast as ast;
 use rustc_hir::diagnostic_items::DiagnosticItems;
+use rustc_hir::OwnerId;
 use rustc_middle::ty::query::Providers;
 use rustc_middle::ty::TyCtxt;
-use rustc_span::def_id::{CrateNum, DefId, LocalDefId, LOCAL_CRATE};
+use rustc_span::def_id::{CrateNum, DefId, LOCAL_CRATE};
 use rustc_span::symbol::{kw::Empty, sym, Symbol};
 
 use crate::errors::{DuplicateDiagnosticItem, DuplicateDiagnosticItemInCrate};
 
-fn observe_item(tcx: TyCtxt<'_>, diagnostic_items: &mut DiagnosticItems, def_id: LocalDefId) {
-    let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
-    let attrs = tcx.hir().attrs(hir_id);
+fn observe_item<'tcx>(tcx: TyCtxt<'tcx>, diagnostic_items: &mut DiagnosticItems, owner: OwnerId) {
+    let attrs = tcx.hir().attrs(owner.into());
     if let Some(name) = extract(attrs) {
         // insert into our table
-        collect_item(tcx, diagnostic_items, name, def_id.to_def_id());
+        collect_item(tcx, diagnostic_items, name, owner.to_def_id());
     }
 }
 
@@ -31,23 +31,33 @@ fn collect_item(tcx: TyCtxt<'_>, items: &mut DiagnosticItems, name: Symbol, item
     items.id_to_name.insert(item_def_id, name);
     if let Some(original_def_id) = items.name_to_id.insert(name, item_def_id) {
         if original_def_id != item_def_id {
-            let orig_span = tcx.hir().span_if_local(original_def_id);
-            let orig_crate_name =
-                orig_span.is_none().then(|| tcx.crate_name(original_def_id.krate));
-            match tcx.hir().span_if_local(item_def_id) {
-                Some(span) => tcx.sess.emit_err(DuplicateDiagnosticItem { span, name }),
-                None => tcx.sess.emit_err(DuplicateDiagnosticItemInCrate {
-                    span: orig_span,
-                    orig_crate_name: orig_crate_name.unwrap_or(Empty),
-                    have_orig_crate_name: orig_crate_name.map(|_| ()),
-                    crate_name: tcx.crate_name(item_def_id.krate),
-                    name,
-                }),
-            };
+            report_duplicate_item(tcx, name, original_def_id, item_def_id);
         }
     }
 }
 
+fn report_duplicate_item(
+    tcx: TyCtxt<'_>,
+    name: Symbol,
+    original_def_id: DefId,
+    item_def_id: DefId,
+) {
+    let (orig_span, orig_crate_name, have_orig_crate_name) = match original_def_id.as_local() {
+        Some(local_original) => (Some(tcx.def_span(local_original)), Empty, None),
+        None => (None, tcx.crate_name(original_def_id.krate), Some(())),
+    };
+    match tcx.hir().span_if_local(item_def_id) {
+        Some(span) => tcx.sess.emit_err(DuplicateDiagnosticItem { span, name }),
+        None => tcx.sess.emit_err(DuplicateDiagnosticItemInCrate {
+            span: orig_span,
+            orig_crate_name,
+            have_orig_crate_name,
+            crate_name: tcx.crate_name(item_def_id.krate),
+            name,
+        }),
+    };
+}
+
 /// Extract the first `rustc_diagnostic_item = "$name"` out of a list of attributes.
 fn extract(attrs: &[ast::Attribute]) -> Option<Symbol> {
     attrs.iter().find_map(|attr| {
@@ -64,21 +74,8 @@ fn diagnostic_items(tcx: TyCtxt<'_>, cnum: CrateNum) -> DiagnosticItems {
 
     // Collect diagnostic items in this crate.
     let crate_items = tcx.hir_crate_items(());
-
-    for id in crate_items.items() {
-        observe_item(tcx, &mut diagnostic_items, id.owner_id.def_id);
-    }
-
-    for id in crate_items.trait_items() {
-        observe_item(tcx, &mut diagnostic_items, id.owner_id.def_id);
-    }
-
-    for id in crate_items.impl_items() {
-        observe_item(tcx, &mut diagnostic_items, id.owner_id.def_id);
-    }
-
-    for id in crate_items.foreign_items() {
-        observe_item(tcx, &mut diagnostic_items, id.owner_id.def_id);
+    for id in crate_items.owners() {
+        observe_item(tcx, &mut diagnostic_items, id);
     }
 
     diagnostic_items