Rollup merge of #138384 - nnethercote:hir-ItemKind-idents, r=fmease

Move `hir::Item::ident` into `hir::ItemKind`.

 `hir::Item` has an `ident` field.

- It's always non-empty for these item kinds: `ExternCrate`, `Static`, `Const`, `Fn`, `Macro`, `Mod`, `TyAlias`, `Enum`, `Struct`, `Union`, Trait`, TraitAalis`.

- It's always empty for these item kinds: `ForeignMod`, `GlobalAsm`, `Impl`.

- For `Use`, it is non-empty for `UseKind::Single` and empty for `UseKind::{Glob,ListStem}`.

All of this is quite non-obvious; the only documentation is a single comment saying "The name might be a dummy name in case of anonymous items". Some sites that handle items check for an empty ident, some don't. This is a very C-like way of doing things, but this is Rust, we have sum types, we can do this properly and never forget to check for the exceptional case and never YOLO possibly empty identifiers (or possibly dummy spans) around and hope that things will work out.

This is step towards `kw::Empty` elimination (#137978).

r? `@fmease`

1 files changed, 14 insertions, 15 deletions

diff --git a/src/librustdoc/html/render/span_map.rs b/src/librustdoc/html/render/span_map.rs
index 3228f71df07..3676051b1bd 100644
--- a/src/librustdoc/html/render/span_map.rs
+++ b/src/librustdoc/html/render/span_map.rs
@@ -242,10 +242,9 @@ impl<'tcx> Visitor<'tcx> for SpanMapVisitor<'tcx> {
             // Now that we confirmed it's a file import, we want to get the span for the module
             // name only and not all the "mod foo;".
             if let Node::Item(item) = self.tcx.hir_node(id) {
-                self.matches.insert(
-                    item.ident.span,
-                    LinkFromSrc::Local(clean::Span::new(m.spans.inner_span)),
-                );
+                let (ident, _) = item.expect_mod();
+                self.matches
+                    .insert(ident.span, LinkFromSrc::Local(clean::Span::new(m.spans.inner_span)));
             }
         } else {
             // If it's a "mod foo {}", we want to look to its documentation page.
@@ -273,22 +272,22 @@ impl<'tcx> Visitor<'tcx> for SpanMapVisitor<'tcx> {
     fn visit_item(&mut self, item: &'tcx Item<'tcx>) {
         match item.kind {
             ItemKind::Static(..)
-            | ItemKind::Const(_, _, _)
+            | ItemKind::Const(..)
             | ItemKind::Fn { .. }
-            | ItemKind::Macro(_, _)
-            | ItemKind::TyAlias(_, _)
-            | ItemKind::Enum(_, _)
-            | ItemKind::Struct(_, _)
-            | ItemKind::Union(_, _)
-            | ItemKind::Trait(_, _, _, _, _)
-            | ItemKind::TraitAlias(_, _) => self.extract_info_from_hir_id(item.hir_id()),
+            | ItemKind::Macro(..)
+            | ItemKind::TyAlias(..)
+            | ItemKind::Enum(..)
+            | ItemKind::Struct(..)
+            | ItemKind::Union(..)
+            | ItemKind::Trait(..)
+            | ItemKind::TraitAlias(..) => self.extract_info_from_hir_id(item.hir_id()),
             ItemKind::Impl(_)
-            | ItemKind::Use(_, _)
-            | ItemKind::ExternCrate(_)
+            | ItemKind::Use(..)
+            | ItemKind::ExternCrate(..)
             | ItemKind::ForeignMod { .. }
             | ItemKind::GlobalAsm { .. }
             // We already have "visit_mod" above so no need to check it here.
-            | ItemKind::Mod(_) => {}
+            | ItemKind::Mod(..) => {}
         }
         intravisit::walk_item(self, item);
     }