Issue 56128 segment id ice nightly

src/librustc/hir/lowering.rs

@@ -2752,7 +2752,7 @@ impl<'a> LoweringContext<'a> {
         id: NodeId,
         name: &mut Name,
         attrs: &hir::HirVec<Attribute>,
-        vis: &mut hir::Visibility,
+        vis: &hir::Visibility,
         i: &ItemKind,
     ) -> hir::ItemKind {
         match *i {
@@ -2955,7 +2955,7 @@ impl<'a> LoweringContext<'a> {
         tree: &UseTree,
         prefix: &Path,
         id: NodeId,
-        vis: &mut hir::Visibility,
+        vis: &hir::Visibility,
         name: &mut Name,
         attrs: &hir::HirVec<Attribute>,
     ) -> hir::ItemKind {
@@ -3029,12 +3029,7 @@ impl<'a> LoweringContext<'a> {
                             hir::VisibilityKind::Inherited => hir::VisibilityKind::Inherited,
                             hir::VisibilityKind::Restricted { ref path, id: _, hir_id: _ } => {
                                 let id = this.next_id();
-                                let mut path = path.clone();
-                                for seg in path.segments.iter_mut() {
-                                    if seg.id.is_some() {
-                                        seg.id = Some(this.next_id().node_id);
-                                    }
-                                }
+                                let path = this.renumber_segment_ids(path);
                                 hir::VisibilityKind::Restricted {
                                     path,
                                     id: id.node_id,
@@ -3091,7 +3086,7 @@ impl<'a> LoweringContext<'a> {
                         hir_id: new_hir_id,
                     } = self.lower_node_id(id);
 
-                    let mut vis = vis.clone();
+                    let vis = vis.clone();
                     let mut name = name.clone();
                     let mut prefix = prefix.clone();
 
@@ -3109,7 +3104,7 @@ impl<'a> LoweringContext<'a> {
                         let item = this.lower_use_tree(use_tree,
                                                        &prefix,
                                                        new_id,
-                                                       &mut vis,
+                                                       &vis,
                                                        &mut name,
                                                        attrs);
 
@@ -3119,8 +3114,9 @@ impl<'a> LoweringContext<'a> {
                             hir::VisibilityKind::Inherited => hir::VisibilityKind::Inherited,
                             hir::VisibilityKind::Restricted { ref path, id: _, hir_id: _ } => {
                                 let id = this.next_id();
+                                let path = this.renumber_segment_ids(path);
                                 hir::VisibilityKind::Restricted {
-                                    path: path.clone(),
+                                    path: path,
                                     id: id.node_id,
                                     hir_id: id.hir_id,
                                 }
@@ -3143,17 +3139,27 @@ impl<'a> LoweringContext<'a> {
                     });
                 }
 
-                // Privatize the degenerate import base, used only to check
-                // the stability of `use a::{};`, to avoid it showing up as
-                // a re-export by accident when `pub`, e.g. in documentation.
                 let def = self.expect_full_def_from_use(id).next().unwrap_or(Def::Err);
                 let path = P(self.lower_path_extra(def, &prefix, ParamMode::Explicit, None));
-                *vis = respan(prefix.span.shrink_to_lo(), hir::VisibilityKind::Inherited);
                 hir::ItemKind::Use(path, hir::UseKind::ListStem)
             }
         }
     }
 
+    /// Paths like the visibility path in `pub(super) use foo::{bar, baz}` are repeated
+    /// many times in the HIR tree; for each occurrence, we need to assign distinct
+    /// node-ids. (See e.g. #56128.)
+    fn renumber_segment_ids(&mut self, path: &P<hir::Path>) -> P<hir::Path> {
+        debug!("renumber_segment_ids(path = {:?})", path);
+        let mut path = path.clone();
+        for seg in path.segments.iter_mut() {
+            if seg.id.is_some() {
+                seg.id = Some(self.next_id().node_id);
+            }
+        }
+        path
+    }
+
     fn lower_trait_item(&mut self, i: &TraitItem) -> hir::TraitItem {
         let LoweredNodeId { node_id, hir_id } = self.lower_node_id(i.id);
         let trait_item_def_id = self.resolver.definitions().local_def_id(node_id);
@@ -3378,7 +3384,7 @@ impl<'a> LoweringContext<'a> {
 
     pub fn lower_item(&mut self, i: &Item) -> Option<hir::Item> {
         let mut name = i.ident.name;
-        let mut vis = self.lower_visibility(&i.vis, None);
+        let vis = self.lower_visibility(&i.vis, None);
         let attrs = self.lower_attrs(&i.attrs);
         if let ItemKind::MacroDef(ref def) = i.node {
             if !def.legacy || attr::contains_name(&i.attrs, "macro_export") ||
@@ -3397,7 +3403,7 @@ impl<'a> LoweringContext<'a> {
             return None;
         }
 
-        let node = self.lower_item_kind(i.id, &mut name, &attrs, &mut vis, &i.node);
+        let node = self.lower_item_kind(i.id, &mut name, &attrs, &vis, &i.node);
 
         let LoweredNodeId { node_id, hir_id } = self.lower_node_id(i.id);
 

src/librustc_lint/builtin.rs

@@ -1136,7 +1136,15 @@ impl UnreachablePub {
 
 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnreachablePub {
     fn check_item(&mut self, cx: &LateContext, item: &hir::Item) {
-        self.perform_lint(cx, "item", item.id, &item.vis, item.span, true);
+        match item.node {
+            hir::ItemKind::Use(_, hir::UseKind::ListStem) => {
+                // Hack: ignore these `use foo::{}` remnants which are just a figment
+                // our IR.
+            }
+            _ => {
+                self.perform_lint(cx, "item", item.id, &item.vis, item.span, true);
+            }
+        }
     }
 
     fn check_foreign_item(&mut self, cx: &LateContext, foreign_item: &hir::ForeignItem) {

src/test/ui/issues/issue-56128.rs

@@ -0,0 +1,15 @@
+// Regression test for #56128. When this `pub(super) use...` gets
+// exploded in the HIR, we were not handling ids correctly.
+//
+// compile-pass
+
+mod bar {
+    pub(super) use self::baz::{x, y};
+
+    mod baz {
+        pub fn x() { }
+        pub fn y() { }
+    }
+}
+
+fn main() { }