Auto merge of #65153 - da-x:issue-58017, r=petrochenkov

Improve message when attempting to instantiate tuple structs with private fields

Fixes #58017, fixes #39703.

```
error[E0603]: tuple struct `Error` is private
  --> main.rs:22:16
   |
2  |     pub struct Error(usize, pub usize, usize);
   |                      -----             ----- field is private
   |                      |
   |                      field is private
...
22 |     let x = a::Error(3, 1, 2);
   |                ^^^^^
   |
   = note: a tuple struct constructor is private if any of its fields is private
```

src/librustc_metadata/cstore_impl.rs

@@ -33,6 +33,7 @@ use syntax::source_map;
 use syntax::edition::Edition;
 use syntax::parse::source_file_to_stream;
 use syntax::parse::parser::emit_unclosed_delims;
+use syntax::source_map::Spanned;
 use syntax::symbol::Symbol;
 use syntax_pos::{Span, FileName};
 use rustc_index::bit_set::BitSet;
@@ -424,8 +425,8 @@ impl cstore::CStore {
         self.get_crate_data(cnum).root.edition
     }
 
-    pub fn struct_field_names_untracked(&self, def: DefId) -> Vec<ast::Name> {
-        self.get_crate_data(def.krate).get_struct_field_names(def.index)
+    pub fn struct_field_names_untracked(&self, def: DefId, sess: &Session) -> Vec<Spanned<Symbol>> {
+        self.get_crate_data(def.krate).get_struct_field_names(def.index, sess)
     }
 
     pub fn ctor_kind_untracked(&self, def: DefId) -> def::CtorKind {

src/librustc_metadata/decoder.rs

@@ -29,7 +29,7 @@ use std::u32;
 use rustc_serialize::{Decodable, Decoder, SpecializedDecoder, opaque};
 use syntax::attr;
 use syntax::ast::{self, Ident};
-use syntax::source_map;
+use syntax::source_map::{self, respan, Spanned};
 use syntax::symbol::{Symbol, sym};
 use syntax::ext::base::{MacroKind, SyntaxExtensionKind, SyntaxExtension};
 use syntax_pos::{self, Span, BytePos, Pos, DUMMY_SP, symbol::{InternedString}};
@@ -1021,11 +1021,11 @@ impl<'a, 'tcx> CrateMetadata {
         Lrc::from(self.get_attributes(&item, sess))
     }
 
-    pub fn get_struct_field_names(&self, id: DefIndex) -> Vec<ast::Name> {
+    pub fn get_struct_field_names(&self, id: DefIndex, sess: &Session) -> Vec<Spanned<ast::Name>> {
         self.entry(id)
             .children
             .decode(self)
-            .map(|index| self.item_name(index))
+            .map(|index| respan(self.get_span(index, sess), self.item_name(index)))
             .collect()
     }
 

src/librustc_resolve/build_reduced_graph.rs

@@ -38,6 +38,7 @@ use syntax::ext::hygiene::ExpnId;
 use syntax::feature_gate::is_builtin_attr;
 use syntax::parse::token::{self, Token};
 use syntax::{span_err, struct_span_err};
+use syntax::source_map::{respan, Spanned};
 use syntax::symbol::{kw, sym};
 use syntax::visit::{self, Visitor};
 
@@ -301,7 +302,7 @@ impl<'a, 'b> BuildReducedGraphVisitor<'a, 'b> {
         }
     }
 
-    fn insert_field_names(&mut self, def_id: DefId, field_names: Vec<Name>) {
+    fn insert_field_names(&mut self, def_id: DefId, field_names: Vec<Spanned<Name>>) {
         if !field_names.is_empty() {
             self.r.field_names.insert(def_id, field_names);
         }
@@ -752,12 +753,12 @@ impl<'a, 'b> BuildReducedGraphVisitor<'a, 'b> {
                 }
 
                 // Record field names for error reporting.
-                let field_names = struct_def.fields().iter().filter_map(|field| {
+                let field_names = struct_def.fields().iter().map(|field| {
                     let field_vis = self.resolve_visibility(&field.vis);
                     if ctor_vis.is_at_least(field_vis, &*self.r) {
                         ctor_vis = field_vis;
                     }
-                    field.ident.map(|ident| ident.name)
+                    respan(field.span, field.ident.map_or(kw::Invalid, |ident| ident.name))
                 }).collect();
                 let item_def_id = self.r.definitions.local_def_id(item.id);
                 self.insert_field_names(item_def_id, field_names);
@@ -779,9 +780,9 @@ impl<'a, 'b> BuildReducedGraphVisitor<'a, 'b> {
                 self.r.define(parent, ident, TypeNS, (res, vis, sp, expansion));
 
                 // Record field names for error reporting.
-                let field_names = vdata.fields().iter().filter_map(|field| {
+                let field_names = vdata.fields().iter().map(|field| {
                     self.resolve_visibility(&field.vis);
-                    field.ident.map(|ident| ident.name)
+                    respan(field.span, field.ident.map_or(kw::Invalid, |ident| ident.name))
                 }).collect();
                 let item_def_id = self.r.definitions.local_def_id(item.id);
                 self.insert_field_names(item_def_id, field_names);
@@ -895,7 +896,8 @@ impl<'a, 'b> BuildReducedGraphVisitor<'a, 'b> {
         // Record some extra data for better diagnostics.
         match res {
             Res::Def(DefKind::Struct, def_id) | Res::Def(DefKind::Union, def_id) => {
-                let field_names = self.r.cstore.struct_field_names_untracked(def_id);
+                let field_names =
+                    self.r.cstore.struct_field_names_untracked(def_id, self.r.session);
                 self.insert_field_names(def_id, field_names);
             }
             Res::Def(DefKind::Method, def_id) => {

src/librustc_resolve/late/diagnostics.rs

@@ -497,7 +497,8 @@ impl<'a> LateResolutionVisitor<'a, '_> {
                         Res::Def(DefKind::Struct, did) | Res::Def(DefKind::Union, did)
                                 if resolution.unresolved_segments() == 0 => {
                             if let Some(field_names) = self.r.field_names.get(&did) {
-                                if field_names.iter().any(|&field_name| ident.name == field_name) {
+                                if field_names.iter()
+                                        .any(|&field_name| ident.name == field_name.node) {
                                     return Some(AssocSuggestion::Field);
                                 }
                             }

src/librustc_resolve/lib.rs

@@ -29,7 +29,7 @@ use rustc::hir::def::{self, DefKind, PartialRes, CtorKind, CtorOf, NonMacroAttrK
 use rustc::hir::def::Namespace::*;
 use rustc::hir::def_id::{CRATE_DEF_INDEX, LOCAL_CRATE, DefId};
 use rustc::hir::{TraitMap, GlobMap};
-use rustc::ty;
+use rustc::ty::{self, DefIdTree};
 use rustc::util::nodemap::{NodeMap, NodeSet, FxHashMap, FxHashSet, DefIdMap};
 use rustc::span_bug;
 
@@ -46,6 +46,7 @@ use syntax::attr;
 use syntax::ast::{CRATE_NODE_ID, Crate};
 use syntax::ast::{ItemKind, Path};
 use syntax::{struct_span_err, unwrap_or};
+use syntax::source_map::Spanned;
 
 use syntax_pos::{Span, DUMMY_SP};
 use errors::{Applicability, DiagnosticBuilder};
@@ -829,7 +830,7 @@ pub struct Resolver<'a> {
 
     /// Names of fields of an item `DefId` accessible with dot syntax.
     /// Used for hints during error reporting.
-    field_names: FxHashMap<DefId, Vec<Name>>,
+    field_names: FxHashMap<DefId, Vec<Spanned<Name>>>,
 
     /// All imports known to succeed or fail.
     determined_imports: Vec<&'a ImportDirective<'a>>,
@@ -994,7 +995,7 @@ impl<'a> AsMut<Resolver<'a>> for Resolver<'a> {
     fn as_mut(&mut self) -> &mut Resolver<'a> { self }
 }
 
-impl<'a, 'b> ty::DefIdTree for &'a Resolver<'b> {
+impl<'a, 'b> DefIdTree for &'a Resolver<'b> {
     fn parent(self, id: DefId) -> Option<DefId> {
         match id.krate {
             LOCAL_CRATE => self.definitions.def_key(id.index).parent,
@@ -2386,23 +2387,17 @@ impl<'a> Resolver<'a> {
                     binding.res().descr(),
                     ident.name,
                 );
-                // FIXME: use the ctor's `def_id` to check wether any of the fields is not visible
-                match binding.kind {
-                    NameBindingKind::Res(Res::Def(DefKind::Ctor(
-                        CtorOf::Struct,
-                        CtorKind::Fn,
-                    ), _def_id), _) => {
-                        err.note("a tuple struct constructor is private if any of its fields \
-                                  is private");
-                    }
-                    NameBindingKind::Res(Res::Def(DefKind::Ctor(
-                        CtorOf::Variant,
-                        CtorKind::Fn,
-                    ), _def_id), _) => {
-                        err.note("a tuple variant constructor is private if any of its fields \
-                                  is private");
+                if let NameBindingKind::Res(
+                    Res::Def(DefKind::Ctor(CtorOf::Struct, CtorKind::Fn), ctor_def_id), _
+                ) = binding.kind {
+                    let def_id = (&*self).parent(ctor_def_id).expect("no parent for a constructor");
+                    if let Some(fields) = self.field_names.get(&def_id) {
+                        let first_field = fields.first().expect("empty field list in the map");
+                        err.span_label(
+                            fields.iter().fold(first_field.span, |acc, field| acc.to(field.span)),
+                            "a tuple struct constructor is private if any of its fields is private",
+                        );
                     }
-                    _ => {}
                 }
                 err.emit();
             }