Changed resolution of enum variants to low priority.

Author: Alexander Regueiro

src/librustc_typeck/astconv.rs

@@ -1292,28 +1292,11 @@ impl<'o, 'gcx: 'tcx, 'tcx> dyn AstConv<'gcx, 'tcx> + 'o {
 
         self.prohibit_generics(slice::from_ref(item_segment));
 
-        // Check if we have an enum variant here.
-        match ty.sty {
-            ty::Adt(adt_def, _) if adt_def.is_enum() => {
-                let variant_def = adt_def.variants.iter().find(|vd| {
-                    tcx.hygienic_eq(assoc_name, vd.ident, adt_def.did)
-                });
-                if let Some(variant_def) = variant_def {
-                    check_type_alias_enum_variants_enabled(tcx, span);
-
-                    let def = Def::Variant(variant_def.did);
-                    tcx.check_stability(def.def_id(), Some(ref_id), span);
-                    return (ty, def);
-                }
-            },
-            _ => (),
-        }
-
         // Find the type of the associated item, and the trait where the associated
         // item is declared.
         let bound = match (&ty.sty, ty_path_def) {
             (_, Def::SelfTy(Some(_), Some(impl_def_id))) => {
-                // `Self` in an impl of a trait -- we have a concrete `self` type and a
+                // `Self` in an impl of a trait -- we have a concrete self type and a
                 // trait reference.
                 let trait_ref = match tcx.impl_trait_ref(impl_def_id) {
                     Some(trait_ref) => trait_ref,
@@ -1365,6 +1348,23 @@ impl<'o, 'gcx: 'tcx, 'tcx> dyn AstConv<'gcx, 'tcx> + 'o {
                 return (tcx.types.err, Def::Err);
             }
             _ => {
+                // Check if we have an enum variant.
+                match ty.sty {
+                    ty::Adt(adt_def, _) if adt_def.is_enum() => {
+                        let variant_def = adt_def.variants.iter().find(|vd| {
+                            tcx.hygienic_eq(assoc_name, vd.ident, adt_def.did)
+                        });
+                        if let Some(variant_def) = variant_def {
+                            check_type_alias_enum_variants_enabled(tcx, span);
+
+                            let def = Def::Variant(variant_def.did);
+                            tcx.check_stability(def.def_id(), Some(ref_id), span);
+                            return (ty, def);
+                        }
+                    },
+                    _ => (),
+                }
+
                 // Don't print `TyErr` to the user.
                 if !ty.references_error() {
                     self.report_ambiguous_associated_type(span,

src/librustc_typeck/check/method/mod.rs

@@ -371,38 +371,43 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
 
         let tcx = self.tcx;
 
-        // Check if we have an enum variant here.
-        match self_ty.sty {
-            ty::Adt(adt_def, _) if adt_def.is_enum() => {
-                let variant_def = adt_def.variants.iter().find(|vd| {
-                    tcx.hygienic_eq(method_name, vd.ident, adt_def.did)
-                });
-                if let Some(variant_def) = variant_def {
-                    check_type_alias_enum_variants_enabled(tcx, span);
-
-                    let def = Def::VariantCtor(variant_def.did, variant_def.ctor_kind);
-                    tcx.check_stability(def.def_id(), Some(expr_id), span);
-                    return Ok(def);
+        let mode = probe::Mode::Path;
+        match self.probe_for_name(span, mode, method_name, IsSuggestion(false),
+                                  self_ty, expr_id, ProbeScope::TraitsInScope) {
+            Ok(pick) => {
+                if let Some(import_id) = pick.import_id {
+                    let import_def_id = tcx.hir().local_def_id(import_id);
+                    debug!("resolve_ufcs: used_trait_import: {:?}", import_def_id);
+                    Lrc::get_mut(&mut self.tables.borrow_mut().used_trait_imports)
+                                                .unwrap().insert(import_def_id);
                 }
-            },
-            _ => (),
-        }
 
-        let mode = probe::Mode::Path;
-        let pick = self.probe_for_name(span, mode, method_name, IsSuggestion(false),
-                                       self_ty, expr_id, ProbeScope::TraitsInScope)?;
+                let def = pick.item.def();
+                tcx.check_stability(def.def_id(), Some(expr_id), span);
 
-        if let Some(import_id) = pick.import_id {
-            let import_def_id = tcx.hir().local_def_id(import_id);
-            debug!("resolve_ufcs: used_trait_import: {:?}", import_def_id);
-            Lrc::get_mut(&mut self.tables.borrow_mut().used_trait_imports)
-                                         .unwrap().insert(import_def_id);
-        }
-
-        let def = pick.item.def();
-        tcx.check_stability(def.def_id(), Some(expr_id), span);
+                Ok(def)
+            }
+            Err(err) => {
+                // Check if we have an enum variant.
+                match self_ty.sty {
+                    ty::Adt(adt_def, _) if adt_def.is_enum() => {
+                        let variant_def = adt_def.variants.iter().find(|vd| {
+                            tcx.hygienic_eq(method_name, vd.ident, adt_def.did)
+                        });
+                        if let Some(variant_def) = variant_def {
+                            check_type_alias_enum_variants_enabled(tcx, span);
+
+                            let def = Def::VariantCtor(variant_def.did, variant_def.ctor_kind);
+                            tcx.check_stability(def.def_id(), Some(expr_id), span);
+                            return Ok(def);
+                        }
+                    },
+                    _ => (),
+                }
 
-        Ok(def)
+                Err(err)
+            }
+        }
     }
 
     /// Find item with name `item_name` defined in impl/trait `def_id`

src/test/ui/bogus-tag.stderr

@@ -1,11 +1,11 @@
 error[E0599]: no variant named `Hsl` found for type `Color` in the current scope
-  --> $DIR/bogus-tag.rs:7:9
+  --> $DIR/bogus-tag.rs:7:16
    |
 LL | enum Color { Rgb(isize, isize, isize), Rgba(isize, isize, isize, isize), }
    | ---------- variant `Hsl` not found here
 ...
 LL |         Color::Hsl(h, s, l) => { println!("hsl"); }
-   |         ^^^^^^^^^^^^^^^^^^^ variant not found in `Color`
+   |         -------^^^--------- variant not found in `Color`
 
 error: aborting due to previous error