Auto merge of #30320 - nrc:err-names, r=@nikomatsakis

We can now handle name resolution errors and get past type checking (if we're a bit lucky). This is the first step towards doing code completion for partial programs (we need error recovery in the parser and early access to save-analysis).

src/librustc/middle/check_static_recursion.rs

@@ -99,8 +99,9 @@ pub fn check_crate<'ast>(sess: &Session,
         ast_map: ast_map,
         discriminant_map: RefCell::new(NodeMap()),
     };
-    krate.visit_all_items(&mut visitor);
-    sess.abort_if_errors();
+    sess.abort_if_new_errors(|| {
+        krate.visit_all_items(&mut visitor);
+    });
 }
 
 struct CheckItemRecursionVisitor<'a, 'ast: 'a> {

src/librustc/middle/def.rs

@@ -52,6 +52,7 @@ pub enum Def {
     DefStruct(DefId),
     DefLabel(ast::NodeId),
     DefMethod(DefId),
+    DefErr,
 }
 
 /// The result of resolving a path.
@@ -124,7 +125,7 @@ impl Def {
             DefVariant(..) | DefTy(..) | DefAssociatedTy(..) |
             DefTyParam(..) | DefUse(..) | DefStruct(..) | DefTrait(..) |
             DefMethod(..) | DefConst(..) | DefAssociatedConst(..) |
-            DefPrimTy(..) | DefLabel(..) | DefSelfTy(..) => {
+            DefPrimTy(..) | DefLabel(..) | DefSelfTy(..) | DefErr => {
                 panic!("attempted .def_id() on invalid {:?}", self)
             }
         }
@@ -142,7 +143,8 @@ impl Def {
 
             DefLabel(..)  |
             DefPrimTy(..) |
-            DefSelfTy(..) => {
+            DefSelfTy(..) |
+            DefErr => {
                 panic!("attempted .def_id() on invalid def: {:?}", self)
             }
         }

src/librustc/middle/mem_categorization.rs

@@ -609,6 +609,8 @@ impl<'t, 'a,'tcx> MemCategorizationContext<'t, 'a, 'tcx> {
                 note: NoteNone
             }))
           }
+
+          def::DefErr => panic!("DefErr in memory categorization")
         }
     }
 
@@ -1196,7 +1198,7 @@ impl<'t, 'a,'tcx> MemCategorizationContext<'t, 'a, 'tcx> {
         (*op)(self, cmt.clone(), pat);
 
         let opt_def = if let Some(path_res) = self.tcx().def_map.borrow().get(&pat.id) {
-            if path_res.depth != 0 {
+            if path_res.depth != 0 || path_res.base_def == def::DefErr {
                 // Since patterns can be associated constants
                 // which are resolved during typeck, we might have
                 // some unresolved patterns reaching this stage
@@ -1261,7 +1263,7 @@ impl<'t, 'a,'tcx> MemCategorizationContext<'t, 'a, 'tcx> {
                 _ => {
                     self.tcx().sess.span_bug(
                         pat.span,
-                        "enum pattern didn't resolve to enum or struct");
+                        &format!("enum pattern didn't resolve to enum or struct {:?}", opt_def));
                 }
             }
           }

src/librustc/middle/resolve_lifetime.rs

@@ -95,15 +95,16 @@ static ROOT_SCOPE: ScopeChain<'static> = RootScope;
 
 pub fn krate(sess: &Session, krate: &hir::Crate, def_map: &DefMap) -> NamedRegionMap {
     let mut named_region_map = NodeMap();
-    krate.visit_all_items(&mut LifetimeContext {
-        sess: sess,
-        named_region_map: &mut named_region_map,
-        scope: &ROOT_SCOPE,
-        def_map: def_map,
-        trait_ref_hack: false,
-        labels_in_fn: vec![],
+    sess.abort_if_new_errors(|| {
+        krate.visit_all_items(&mut LifetimeContext {
+            sess: sess,
+            named_region_map: &mut named_region_map,
+            scope: &ROOT_SCOPE,
+            def_map: def_map,
+            trait_ref_hack: false,
+            labels_in_fn: vec![],
+        });
     });
-    sess.abort_if_errors();
     named_region_map
 }
 

src/librustc/middle/ty/mod.rs

@@ -2100,9 +2100,8 @@ impl<'tcx> ctxt<'tcx> {
                     }) => {
                         true
                     }
-
+                    Some(&def::PathResolution { base_def: def::DefErr, .. })=> true,
                     Some(..) => false,
-
                     None => self.sess.span_bug(expr.span, &format!(
                         "no def for path {}", expr.id))
                 }

src/librustc/session/mod.rs

@@ -156,6 +156,15 @@ impl Session {
             _ => {}
         }
     }
+    pub fn abort_if_new_errors<F>(&self, mut f: F)
+        where F: FnMut()
+    {
+        let count = self.err_count();
+        f();
+        if self.err_count() > count {
+            self.abort_if_errors();
+        }
+    }
     pub fn span_warn(&self, sp: Span, msg: &str) {
         if self.can_print_warnings {
             self.diagnostic().span_warn(sp, msg)

src/librustc_metadata/astencode.rs

@@ -407,7 +407,8 @@ impl tr for def::Def {
               def::DefUpvar(did1, nid1, index, nid2)
           }
           def::DefStruct(did) => def::DefStruct(did.tr(dcx)),
-          def::DefLabel(nid) => def::DefLabel(dcx.tr_id(nid))
+          def::DefLabel(nid) => def::DefLabel(dcx.tr_id(nid)),
+          def::DefErr => def::DefErr,
         }
     }
 }

src/librustc_resolve/build_reduced_graph.rs

@@ -709,7 +709,8 @@ impl<'a, 'b:'a, 'tcx:'b> GraphBuilder<'a, 'b, 'tcx> {
             DefUse(..) |
             DefUpvar(..) |
             DefLabel(..) |
-            DefSelfTy(..) => {
+            DefSelfTy(..) |
+            DefErr => {
                 panic!("didn't expect `{:?}`", def);
             }
         }

src/librustc_resolve/lib.rs

@@ -566,6 +566,7 @@ impl<'a, 'v, 'tcx> Visitor<'v> for Resolver<'a, 'tcx> {
             Ok(def) => self.record_def(tref.trait_ref.ref_id, def),
             Err(_) => {
                 // error already reported
+                self.record_def(tref.trait_ref.ref_id, err_path_resolution())
             }
         }
         intravisit::walk_poly_trait_ref(self, tref, m);
@@ -2005,6 +2006,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
                                                   prefix.span,
                                                   ResolutionError::FailedToResolve(
                                                       &path_names_to_string(prefix, 0)));
+                                    self.record_def(item.id, err_path_resolution());
                                 }
                             }
                         }
@@ -2164,6 +2166,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
                         resolve_error(self,
                                       eq_pred.span,
                                       ResolutionError::UndeclaredAssociatedType);
+                        self.record_def(eq_pred.id, err_path_resolution());
                     }
                 }
             }
@@ -2194,6 +2197,8 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
                 self.record_def(trait_ref.ref_id, path_res);
                 new_val = Some((path_res.base_def.def_id(), trait_ref.clone()));
                 new_id = Some(path_res.base_def.def_id());
+            } else {
+                self.record_def(trait_ref.ref_id, err_path_resolution());
             }
             intravisit::walk_trait_ref(self, trait_ref);
         }
@@ -2463,6 +2468,8 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
                         self.record_def(ty.id, def);
                     }
                     None => {
+                        self.record_def(ty.id, err_path_resolution());
+
                         // Keep reporting some errors even if they're ignored above.
                         self.resolve_path(ty.id, path, 0, TypeNS, true);
 
@@ -2545,6 +2552,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
                                 ResolutionError::DeclarationShadowsEnumVariantOrUnitLikeStruct(
                                     renamed)
                             );
+                            self.record_def(pattern.id, err_path_resolution());
                         }
                         FoundConst(def, lp, _) if const_ok => {
                             debug!("(resolving pattern) resolving `{}` to constant", renamed);
@@ -2564,6 +2572,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
                                 ResolutionError::OnlyIrrefutablePatternsAllowedHere(def.def_id(),
                                                                                     name)
                             );
+                            self.record_def(pattern.id, err_path_resolution());
                         }
                         BareIdentifierPatternUnresolved => {
                             debug!("(resolving pattern) binding `{}`", renamed);
@@ -2647,6 +2656,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
                                 resolve_error(&self,
                                               path.span,
                                               ResolutionError::StaticVariableReference);
+                                self.record_def(pattern.id, err_path_resolution());
                             }
                             _ => {
                                 // If anything ends up here entirely resolved,
@@ -2665,6 +2675,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
                                                  .name
                                                  .as_str())
                                     );
+                                    self.record_def(pattern.id, err_path_resolution());
                                 } else {
                                     let const_name = path.segments
                                                          .last()
@@ -2684,6 +2695,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
                             ResolutionError::UnresolvedEnumVariantStructOrConst(
                                 &path.segments.last().unwrap().identifier.name.as_str())
                         );
+                        self.record_def(pattern.id, err_path_resolution());
                     }
                     intravisit::walk_path(self, path);
                 }
@@ -2726,6 +2738,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
                                         &path.segments.last().unwrap().identifier.name.as_str()
                                     )
                                 );
+                                self.record_def(pattern.id, err_path_resolution());
                             }
                         }
                     } else {
@@ -2737,6 +2750,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
                                                                                       .identifier
                                                                                       .name
                                                                                       .as_str()));
+                        self.record_def(pattern.id, err_path_resolution());
                     }
                     intravisit::walk_pat(self, pattern);
                 }
@@ -2754,6 +2768,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
                                 ResolutionError::DoesNotNameAStruct(
                                     &*path_names_to_string(path, 0))
                             );
+                            self.record_def(pattern.id, err_path_resolution());
                         }
                     }
                     intravisit::walk_path(self, path);
@@ -3430,6 +3445,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
                         } else {
                             self.session.span_help(expr.span, &msg);
                         }
+                        self.record_def(expr.id, err_path_resolution());
                     } else {
                         // Write the result into the def map.
                         debug!("(resolving expr) resolved `{}`",
@@ -3454,6 +3470,8 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
                     let type_res = self.with_no_errors(|this| {
                         this.resolve_path(expr.id, path, 0, TypeNS, false)
                     });
+
+                    self.record_def(expr.id, err_path_resolution());
                     match type_res.map(|r| r.base_def) {
                         Some(DefTy(struct_id, _)) if self.structs.contains_key(&struct_id) => {
                             resolve_error(
@@ -3540,6 +3558,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
                                       ResolutionError::DoesNotNameAStruct(
                                                                 &*path_names_to_string(path, 0))
                                      );
+                        self.record_def(expr.id, err_path_resolution());
                     }
                 }
 
@@ -3562,6 +3581,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
             ExprBreak(Some(label)) | ExprAgain(Some(label)) => {
                 match self.search_label(label.node.name) {
                     None => {
+                        self.record_def(expr.id, err_path_resolution());
                         resolve_error(self,
                                       label.span,
                                       ResolutionError::UndeclaredLabel(&label.node.name.as_str()))
@@ -3811,6 +3831,14 @@ fn module_to_string(module: &Module) -> String {
     names_to_string(&names.into_iter().rev().collect::<Vec<ast::Name>>())
 }
 
+fn err_path_resolution() -> PathResolution {
+    PathResolution {
+        base_def: DefErr,
+        last_private: LastMod(AllPublic),
+        depth: 0,
+    }
+}
+
 
 pub struct CrateMap {
     pub def_map: RefCell<DefMap>,
@@ -3836,7 +3864,6 @@ pub fn resolve_crate<'a, 'tcx>(session: &'a Session,
     let mut resolver = create_resolver(session, ast_map, krate, make_glob_map, None);
 
     resolver.resolve_crate(krate);
-    session.abort_if_errors();
 
     check_unused::check_crate(&mut resolver, krate);
 

src/librustc_trans/save/dump_csv.rs

@@ -276,7 +276,8 @@ impl <'l, 'tcx> DumpCsvVisitor<'l, 'tcx> {
             def::DefTyParam(..) |
             def::DefUse(_) |
             def::DefMethod(..) |
-            def::DefPrimTy(_) => {
+            def::DefPrimTy(_) |
+            def::DefErr => {
                 self.sess.span_bug(span,
                                    &format!("lookup_def_kind for unexpected item: {:?}", def));
             }

src/librustc_trans/trans/callee.rs

@@ -216,7 +216,7 @@ fn trans<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, expr: &hir::Expr)
             def::DefMod(..) | def::DefForeignMod(..) | def::DefTrait(..) |
             def::DefTy(..) | def::DefPrimTy(..) | def::DefAssociatedTy(..) |
             def::DefUse(..) | def::DefLabel(..) | def::DefTyParam(..) |
-            def::DefSelfTy(..) => {
+            def::DefSelfTy(..) | def::DefErr => {
                 bcx.tcx().sess.span_bug(
                     ref_expr.span,
                     &format!("cannot translate def {:?} \

src/librustc_typeck/astconv.rs

@@ -719,6 +719,9 @@ fn trait_def_id<'tcx>(this: &AstConv<'tcx>, trait_ref: &hir::TraitRef) -> DefId
     let path = &trait_ref.path;
     match ::lookup_full_def(this.tcx(), path.span, trait_ref.ref_id) {
         def::DefTrait(trait_def_id) => trait_def_id,
+        def::DefErr => {
+            this.tcx().sess.fatal("cannot continue compilation due to previous error");
+        }
         _ => {
             span_fatal!(this.tcx().sess, path.span, E0245, "`{}` is not a trait",
                         path);
@@ -1533,6 +1536,9 @@ fn base_def_to_ty<'tcx>(this: &AstConv<'tcx>,
         def::DefPrimTy(prim_ty) => {
             prim_ty_to_ty(tcx, base_segments, prim_ty)
         }
+        def::DefErr => {
+            return this.tcx().types.err;
+        }
         _ => {
             let id_node = tcx.map.as_local_node_id(def.def_id()).unwrap();
             span_err!(tcx.sess, span, E0248,