Fix ICE when using #[doc(keyword = "...")] on non-items

compiler/rustc_passes/src/check_attr.rs

@@ -525,8 +525,11 @@ impl CheckAttrVisitor<'tcx> {
             self.doc_attr_str_error(meta, "keyword");
             return false;
         }
-        match self.tcx.hir().expect_item(hir_id).kind {
+        match self.tcx.hir().find(hir_id).and_then(|node| match node {
-            ItemKind::Mod(ref module) => {
+            hir::Node::Item(item) => Some(&item.kind),
+            _ => None,
+        }) {
+            Some(ItemKind::Mod(ref module)) => {
                 if !module.item_ids.is_empty() {
                     self.tcx
                         .sess

src/test/ui/rustdoc/issue-83512.rs

@@ -0,0 +1,10 @@
+// Regression test for the ICE described in #83512.
+
+#![feature(doc_keyword)]
+#![crate_type="lib"]
+
+trait Foo {
+    #[doc(keyword = "match")]
+    //~^ ERROR: `#[doc(keyword = "...")]` can only be used on modules
+    fn quux() {}
+}

src/test/ui/rustdoc/issue-83512.stderr

@@ -0,0 +1,8 @@
+error: `#[doc(keyword = "...")]` can only be used on modules
+  --> $DIR/issue-83512.rs:7:11
+   |
+LL |     #[doc(keyword = "match")]
+   |           ^^^^^^^^^^^^^^^^^
+
+error: aborting due to previous error
+