Make generics always have a valid span

Author: estebank

src/librustc/hir/map/mod.rs

@@ -628,10 +628,6 @@ impl<'hir> Map<'hir> {
         })
     }
 
-    pub fn get_generics_span(&self, id: DefId) -> Option<Span> {
-        self.get_generics(id).map(|generics| generics.span).filter(|sp| *sp != DUMMY_SP)
-    }
-
     /// Retrieves the `Node` corresponding to `id`, returning `None` if cannot be found.
     pub fn find(&self, id: NodeId) -> Option<Node<'hir>> {
         let hir_id = self.node_to_hir_id(id);

src/librustc_typeck/check/compare_method.rs

@@ -385,7 +385,7 @@ fn check_region_bounds_on_impl_method<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
     // the moment, give a kind of vague error message.
     if trait_params != impl_params {
         let def_span = tcx.sess.source_map().def_span(span);
-        let span = tcx.hir().get_generics_span(impl_m.def_id).unwrap_or(def_span);
+        let span = tcx.hir().get_generics(impl_m.def_id).map(|g| g.span).unwrap_or(def_span);
         let mut err = struct_span_err!(
             tcx.sess,
             span,
@@ -396,7 +396,7 @@ fn check_region_bounds_on_impl_method<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
         err.span_label(span, "lifetimes do not match method in trait");
         if let Some(sp) = tcx.hir().span_if_local(trait_m.def_id) {
             let def_sp = tcx.sess.source_map().def_span(sp);
-            let sp = tcx.hir().get_generics_span(trait_m.def_id).unwrap_or(def_sp);
+            let sp = tcx.hir().get_generics(trait_m.def_id).map(|g| g.span).unwrap_or(def_sp);
             err.span_label(sp, "lifetimes in impl do not match this method in trait");
         }
         err.emit();

src/libsyntax/parse/parser.rs

@@ -5050,21 +5050,22 @@ impl<'a> Parser<'a> {
     /// where   typaramseq = ( typaram ) | ( typaram , typaramseq )
     fn parse_generics(&mut self) -> PResult<'a, ast::Generics> {
         let span_lo = self.span;
-        if self.eat_lt() {
+        let (params, span) = if self.eat_lt() {
             let params = self.parse_generic_params()?;
             self.expect_gt()?;
-            Ok(ast::Generics {
-                params,
-                where_clause: WhereClause {
-                    id: ast::DUMMY_NODE_ID,
-                    predicates: Vec::new(),
-                    span: DUMMY_SP,
-                },
-                span: span_lo.to(self.prev_span),
-            })
+            (params, span_lo.to(self.prev_span))
         } else {
-            Ok(ast::Generics::default())
-        }
+            (vec![], self.prev_span.between(self.span))
+        };
+        Ok(ast::Generics {
+            params,
+            where_clause: WhereClause {
+                id: ast::DUMMY_NODE_ID,
+                predicates: Vec::new(),
+                span: DUMMY_SP,
+            },
+            span,
+        })
     }
 
     /// Parses generic args (within a path segment) with recovery for extra leading angle brackets.

src/test/ui/borrowck/regions-bound-missing-bound-in-impl.stderr

@@ -36,13 +36,13 @@ LL |     fn wrong_bound1<'b,'c,'d:'a+'c>(self, b: Inv<'b>, c: Inv<'c>, d: Inv<'d
    |                        ^^
 
 error[E0195]: lifetime parameters or bounds on method `wrong_bound2` do not match the trait declaration
-  --> $DIR/regions-bound-missing-bound-in-impl.rs:41:5
+  --> $DIR/regions-bound-missing-bound-in-impl.rs:41:20
    |
 LL |     fn wrong_bound2<'b,'c,'d:'a+'b>(self, b: Inv<'b>, c: Inv<'c>, d: Inv<'d>);
    |                    ---------------- lifetimes in impl do not match this method in trait
 ...
 LL |     fn wrong_bound2(self, b: Inv, c: Inv, d: Inv) {
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ lifetimes do not match method in trait
+   |                    ^ lifetimes do not match method in trait
 
 error[E0276]: impl has stricter requirements than trait
   --> $DIR/regions-bound-missing-bound-in-impl.rs:48:5

src/test/ui/issues/type-arg-mismatch-due-to-impl-trait.stderr

@@ -1,11 +1,11 @@
 error[E0049]: method `foo` has 1 type parameter but its trait declaration has 0 type parameters
-  --> $DIR/type-arg-mismatch-due-to-impl-trait.rs:10:5
+  --> $DIR/type-arg-mismatch-due-to-impl-trait.rs:10:11
    |
 LL |     fn foo(&self, t: Self::T);
    |     -------------------------- expected 0 type parameters
 ...
 LL |     fn foo(&self, t: impl Clone) {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ found 1 type parameter
+   |           ^ found 1 type parameter
 
 error: aborting due to previous error