Auto merge of #45707 - Ryman:deprecated-item-name, r=nikomatsakis

rustc: add item name to deprecated lint warning

It can sometimes be difficult to know what is actually deprecated when you have `foo.bar()` and `bar` comes from a trait in another crate.

Author: bors

src/librustc/middle/stability.rs

@@ -516,11 +516,13 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
             return;
         }
 
-        let lint_deprecated = |note: Option<Symbol>| {
+        let lint_deprecated = |def_id: DefId, note: Option<Symbol>| {
+            let path = self.item_path_str(def_id);
+
             let msg = if let Some(note) = note {
-                format!("use of deprecated item: {}", note)
+                format!("use of deprecated item '{}': {}", path, note)
             } else {
-                format!("use of deprecated item")
+                format!("use of deprecated item '{}'", path)
             };
 
             self.lint_node(lint::builtin::DEPRECATED, id, span, &msg);
@@ -538,7 +540,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
             };
 
             if !skip {
-                lint_deprecated(depr_entry.attr.note);
+                lint_deprecated(def_id, depr_entry.attr.note);
             }
         }
 
@@ -557,7 +559,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
         if let Some(&Stability{rustc_depr: Some(attr::RustcDeprecation { reason, .. }), ..})
                 = stability {
             if id != ast::DUMMY_NODE_ID {
-                lint_deprecated(Some(reason));
+                lint_deprecated(def_id, Some(reason));
             }
         }
 

src/librustc/ty/item_path.rs

@@ -151,9 +151,23 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
                 }
             }
 
-            cur_path.push(self.def_key(cur_def)
-                              .disambiguated_data.data.get_opt_name().unwrap_or_else(||
-                Symbol::intern("<unnamed>").as_str()));
+            let mut cur_def_key = self.def_key(cur_def);
+
+            // For a UnitStruct or TupleStruct we want the name of its parent rather than <unnamed>.
+            if let DefPathData::StructCtor = cur_def_key.disambiguated_data.data {
+                let parent = DefId {
+                    krate: cur_def.krate,
+                    index: cur_def_key.parent.expect("DefPathData::StructCtor missing a parent"),
+                };
+
+                cur_def_key = self.def_key(parent);
+            }
+
+            let data = cur_def_key.disambiguated_data.data;
+            let symbol =
+                data.get_opt_name().unwrap_or_else(|| Symbol::intern("<unnamed>").as_str());
+            cur_path.push(symbol);
+
             match visible_parent_map.get(&cur_def) {
                 Some(&def) => cur_def = def,
                 None => return false,

src/test/compile-fail/auxiliary/deprecation-lint.rs

@@ -52,6 +52,24 @@ pub enum Enum {
 #[deprecated(since = "1.0.0", note = "text")]
 pub struct DeprecatedTupleStruct(pub isize);
 
+pub mod nested {
+    #[deprecated(since = "1.0.0", note = "text")]
+    pub struct DeprecatedStruct {
+        pub i: isize
+    }
+
+    #[deprecated(since = "1.0.0", note = "text")]
+    pub struct DeprecatedUnitStruct;
+
+    pub enum Enum {
+        #[deprecated(since = "1.0.0", note = "text")]
+        DeprecatedVariant,
+    }
+
+    #[deprecated(since = "1.0.0", note = "text")]
+    pub struct DeprecatedTupleStruct(pub isize);
+}
+
 pub struct Stable {
     #[deprecated(since = "1.0.0", note = "text")]
     pub override2: u8,