Streamline some PerNS uses.

Author: nnethercote

compiler/rustc_ast_lowering/src/lib.rs

@@ -706,18 +706,16 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
     }
 
     fn lower_import_res(&mut self, id: NodeId, span: Span) -> PerNS<Option<Res>> {
-        let PerNS { type_ns, value_ns, macro_ns } = self.resolver.get_import_res(id);
-        let mut l = |ns: Option<_>| ns.map(|res| self.lower_res(res));
-        let mut res = PerNS { type_ns: l(type_ns), value_ns: l(value_ns), macro_ns: l(macro_ns) };
-
-        if res.type_ns.is_none() && res.value_ns.is_none() && res.macro_ns.is_none() {
+        let per_ns = self.resolver.get_import_res(id);
+        let mut per_ns = per_ns.map(|res| res.map(|res| self.lower_res(res)));
+        if per_ns.is_empty() {
             // Mark all namespaces with error, just to be sure.
             // Propagate the error to all namespaces, just to be sure.
             let err = Some(Res::Err);
-            res = PerNS { type_ns: err, value_ns: err, macro_ns: err };
+            per_ns = PerNS { type_ns: err, value_ns: err, macro_ns: err };
             self.dcx().span_delayed_bug(span, "no resolution for an import");
         }
-        res
+        per_ns
     }
 
     fn make_lang_item_qpath(

compiler/rustc_hir/src/intravisit.rs

@@ -69,7 +69,6 @@ use rustc_ast::visit::{VisitorResult, try_visit, visit_opt, walk_list};
 use rustc_span::def_id::LocalDefId;
 use rustc_span::{Ident, Span, Symbol};
 
-use crate::def::PerNS;
 use crate::hir::*;
 
 pub trait IntoVisitor<'hir> {
@@ -1148,15 +1147,9 @@ pub fn walk_use<'v, V: Visitor<'v>>(
     path: &'v UsePath<'v>,
     hir_id: HirId,
 ) -> V::Result {
-    let UsePath { segments, res: PerNS { value_ns, type_ns, macro_ns }, span } = *path;
-    if let Some(value_ns) = value_ns {
-        try_visit!(visitor.visit_path(&Path { segments, res: value_ns, span }, hir_id));
-    }
-    if let Some(type_ns) = type_ns {
-        try_visit!(visitor.visit_path(&Path { segments, res: type_ns, span }, hir_id));
-    }
-    if let Some(macro_ns) = macro_ns {
-        try_visit!(visitor.visit_path(&Path { segments, res: macro_ns, span }, hir_id));
+    let UsePath { segments, ref res, span } = *path;
+    for res in res.present_items() {
+        try_visit!(visitor.visit_path(&Path { segments, res, span }, hir_id));
     }
     V::Result::output()
 }

compiler/rustc_lint/src/unqualified_local_imports.rs

@@ -50,8 +50,7 @@ impl<'tcx> LateLintPass<'tcx> for UnqualifiedLocalImports {
         let is_local_import = matches!(
             path.res.type_ns,
             Some(hir::def::Res::Def(_, def_id)) if def_id.is_local()
-        )
-        || matches!(
+        ) || matches!(
             path.res.value_ns,
             Some(hir::def::Res::Def(_, def_id)) if def_id.is_local()
         );