rust-lang · bors · Jan 18, 2020 · Jan 10, 2020 · Jan 10, 2020 · Jan 10, 2020
diff --git a/src/librustc/hir/check_attr.rs b/src/librustc/hir/check_attr.rs
@@ -112,7 +112,7 @@ impl Target {
             ItemKind::Union(..) => Target::Union,
             ItemKind::Trait(..) => Target::Trait,
             ItemKind::TraitAlias(..) => Target::TraitAlias,
-            ItemKind::Impl(..) => Target::Impl,
+            ItemKind::Impl { .. } => Target::Impl,
         }
     }
 
@@ -144,7 +144,7 @@ impl Target {
                 let parent_hir_id = tcx.hir().get_parent_item(impl_item.hir_id);
                 let containing_item = tcx.hir().expect_item(parent_hir_id);
                 let containing_impl_is_for_trait = match &containing_item.kind {
-                    hir::ItemKind::Impl(_, _, _, _, tr, _, _) => tr.is_some(),
+                    hir::ItemKind::Impl { ref of_trait, .. } => of_trait.is_some(),
                     _ => bug!("parent of an ImplItem must be an Impl"),
                 };
                 if containing_impl_is_for_trait {

diff --git a/src/librustc/hir/map/mod.rs b/src/librustc/hir/map/mod.rs
@@ -341,7 +341,7 @@ impl<'hir> Map<'hir> {
                 | ItemKind::Use(..)
                 | ItemKind::ForeignMod(..)
                 | ItemKind::GlobalAsm(..)
-                | ItemKind::Impl(..) => return None,
+                | ItemKind::Impl { .. } => return None,
             },
             Node::ForeignItem(item) => match item.kind {
                 ForeignItemKind::Fn(..) => DefKind::Fn,
@@ -604,7 +604,7 @@ impl<'hir> Map<'hir> {
                 | ItemKind::Union(_, ref generics)
                 | ItemKind::Trait(_, _, ref generics, ..)
                 | ItemKind::TraitAlias(ref generics, _)
-                | ItemKind::Impl(_, _, _, ref generics, ..) => Some(generics),
+                | ItemKind::Impl { ref generics, .. } => Some(generics),
                 _ => None,
             },
             _ => None,
@@ -821,7 +821,7 @@ impl<'hir> Map<'hir> {
                     | ItemKind::Struct(..)
                     | ItemKind::Union(..)
                     | ItemKind::Trait(..)
-                    | ItemKind::Impl(..) => true,
+                    | ItemKind::Impl { .. } => true,
                     _ => false,
                 },
                 Node::ForeignItem(fi) => match fi.kind {
@@ -1332,7 +1332,7 @@ fn hir_id_to_string(map: &Map<'_>, id: HirId, include_id: bool) -> String {
                 ItemKind::Union(..) => "union",
                 ItemKind::Trait(..) => "trait",
                 ItemKind::TraitAlias(..) => "trait alias",
-                ItemKind::Impl(..) => "impl",
+                ItemKind::Impl { .. } => "impl",
             };
             format!("{} {}{}", item_str, path_str(), id_str)
         }

diff --git a/src/librustc/infer/error_reporting/mod.rs b/src/librustc/infer/error_reporting/mod.rs
@@ -254,7 +254,7 @@ fn emit_msg_span(
 
 fn item_scope_tag(item: &hir::Item<'_>) -> &'static str {
     match item.kind {
-        hir::ItemKind::Impl(..) => "impl",
+        hir::ItemKind::Impl { .. } => "impl",
         hir::ItemKind::Struct(..) => "struct",
         hir::ItemKind::Union(..) => "union",
         hir::ItemKind::Enum(..) => "enum",

diff --git a/src/librustc/traits/error_reporting/suggestions.rs b/src/librustc/traits/error_reporting/suggestions.rs
@@ -88,8 +88,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
                     ..
                 })
                 | hir::Node::Item(hir::Item {
-                    kind: hir::ItemKind::Impl(_, _, _, generics, ..),
-                    ..
+                    kind: hir::ItemKind::Impl { generics, .. }, ..
                 }) if projection.is_some() => {
                     // Missing associated type bound.
                     suggest_restriction(&generics, "the associated type", err);
@@ -115,7 +114,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
                     ..
                 })
                 | hir::Node::Item(hir::Item {
-                    kind: hir::ItemKind::Impl(_, _, _, generics, ..),
+                    kind: hir::ItemKind::Impl { generics, .. },
                     span,
                     ..
                 })

diff --git a/src/librustc/traits/util.rs b/src/librustc/traits/util.rs
@@ -651,7 +651,7 @@ pub fn impl_is_default(tcx: TyCtxt<'_>, node_item_def_id: DefId) -> bool {
     match tcx.hir().as_local_hir_id(node_item_def_id) {
         Some(hir_id) => {
             let item = tcx.hir().expect_item(hir_id);
-            if let hir::ItemKind::Impl(_, _, defaultness, ..) = item.kind {
+            if let hir::ItemKind::Impl { defaultness, .. } = item.kind {
                 defaultness.is_default()
             } else {
                 false

diff --git a/src/librustc/traits/wf.rs b/src/librustc/traits/wf.rs
@@ -229,9 +229,9 @@ impl<'a, 'tcx> WfPredicates<'a, 'tcx> {
                         //      |
                         //      = note: expected type `u32`
                         //                 found type `()`
-                        if let Some(hir::ItemKind::Impl(.., impl_items)) = item.map(|i| &i.kind) {
+                        if let Some(hir::ItemKind::Impl { items, .. }) = item.map(|i| &i.kind) {
                             let trait_assoc_item = tcx.associated_item(proj.projection_def_id());
-                            if let Some(impl_item) = impl_items
+                            if let Some(impl_item) = items
                                 .iter()
                                 .filter(|item| item.ident == trait_assoc_item.ident)
                                 .next()
@@ -279,14 +279,14 @@ impl<'a, 'tcx> WfPredicates<'a, 'tcx> {
                         //      |     ^^^^^^^^^^^^^^^^^^ the trait `Bar` is not implemented for `bool`
                         if let (
                             ty::Projection(ty::ProjectionTy { item_def_id, .. }),
-                            Some(hir::ItemKind::Impl(.., impl_items)),
+                            Some(hir::ItemKind::Impl { items, .. }),
                         ) = (&proj.skip_binder().self_ty().kind, item.map(|i| &i.kind))
                         {
                             if let Some((impl_item, trait_assoc_item)) = trait_assoc_items
                                 .filter(|i| i.def_id == *item_def_id)
                                 .next()
                                 .and_then(|trait_assoc_item| {
-                                    impl_items
+                                    items
                                         .iter()
                                         .filter(|i| i.ident == trait_assoc_item.ident)
                                         .next()

diff --git a/src/librustc_ast_lowering/item.rs b/src/librustc_ast_lowering/item.rs
@@ -67,14 +67,15 @@ impl<'a> Visitor<'a> for ItemLowerer<'a, '_, '_> {
         if let Some(hir_id) = item_hir_id {
             self.lctx.with_parent_item_lifetime_defs(hir_id, |this| {
                 let this = &mut ItemLowerer { lctx: this };
-                if let ItemKind::Impl(.., ref opt_trait_ref, _, _) = item.kind {
-                    if opt_trait_ref.as_ref().map(|tr| tr.constness.is_some()).unwrap_or(false) {
+                if let ItemKind::Impl { ref of_trait, .. } = item.kind {
+                    if of_trait.as_ref().map(|tr| tr.constness.is_some()).unwrap_or(false) {
+                        this.with_trait_impl_ref(of_trait, |this| visit::walk_item(this, item));
                         this.lctx
                             .diagnostic()
                             .span_err(item.span, "const trait impls are not yet implemented");
                     }
 
-                    this.with_trait_impl_ref(opt_trait_ref, |this| visit::walk_item(this, item));
+                    this.with_trait_impl_ref(of_trait, |this| visit::walk_item(this, item));
                 } else {
                     visit::walk_item(this, item);
                 }
@@ -118,7 +119,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
         let old_len = self.in_scope_lifetimes.len();
 
         let parent_generics = match self.items.get(&parent_hir_id).unwrap().kind {
-            hir::ItemKind::Impl(_, _, _, ref generics, ..)
+            hir::ItemKind::Impl { ref generics, .. }
             | hir::ItemKind::Trait(_, _, ref generics, ..) => &generics.params[..],
             _ => &[],
         };
@@ -173,7 +174,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 vec
             }
             ItemKind::MacroDef(..) => SmallVec::new(),
-            ItemKind::Fn(..) | ItemKind::Impl(.., None, _, _) => smallvec![i.id],
+            ItemKind::Fn(..) | ItemKind::Impl { of_trait: None, .. } => smallvec![i.id],
             ItemKind::Static(ref ty, ..) => {
                 let mut ids = smallvec![i.id];
                 if self.sess.features_untracked().impl_trait_in_bindings {
@@ -361,15 +362,15 @@ impl<'hir> LoweringContext<'_, 'hir> {
                     self.lower_generics(generics, ImplTraitContext::disallowed()),
                 )
             }
-            ItemKind::Impl(
+            ItemKind::Impl {
                 unsafety,
                 polarity,
                 defaultness,
-                ref ast_generics,
-                ref trait_ref,
-                ref ty,
-                ref impl_items,
-            ) => {
+                generics: ref ast_generics,
+                of_trait: ref trait_ref,
+                self_ty: ref ty,
+                items: ref impl_items,
+            } => {
                 let def_id = self.resolver.definitions().local_def_id(id);
 
                 // Lower the "impl header" first. This ordering is important
@@ -417,15 +418,15 @@ impl<'hir> LoweringContext<'_, 'hir> {
                         )
                     });
 
-                hir::ItemKind::Impl(
+                hir::ItemKind::Impl {
                     unsafety,
                     polarity,
-                    self.lower_defaultness(defaultness, true /* [1] */),
+                    defaultness: self.lower_defaultness(defaultness, true /* [1] */),
                     generics,
-                    trait_ref,
-                    lowered_ty,
-                    new_impl_items,
-                )
+                    of_trait: trait_ref,
+                    self_ty: lowered_ty,
+                    items: new_impl_items,
+                }
             }
             ItemKind::Trait(is_auto, unsafety, ref generics, ref bounds, ref items) => {
                 let bounds = self.lower_param_bounds(bounds, ImplTraitContext::disallowed());

diff --git a/src/librustc_ast_passes/ast_validation.rs b/src/librustc_ast_passes/ast_validation.rs
@@ -612,9 +612,17 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
         }
 
         match item.kind {
-            ItemKind::Impl(unsafety, polarity, _, _, Some(..), ref ty, ref impl_items) => {
+            ItemKind::Impl {
+                unsafety,
+                polarity,
+                defaultness: _,
+                generics: _,
+                of_trait: Some(_),
+                ref self_ty,
+                ref items,
+            } => {
                 self.invalid_visibility(&item.vis, None);
-                if let TyKind::Err = ty.kind {
+                if let TyKind::Err = self_ty.kind {
                     self.err_handler()
                         .struct_span_err(item.span, "`impl Trait for .. {}` is an obsolete syntax")
                         .help("use `auto trait Trait {}` instead")
@@ -629,15 +637,23 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
                     )
                     .emit();
                 }
-                for impl_item in impl_items {
+                for impl_item in items {
                     self.invalid_visibility(&impl_item.vis, None);
                     if let AssocItemKind::Fn(ref sig, _) = impl_item.kind {
                         self.check_trait_fn_not_const(sig.header.constness);
                         self.check_trait_fn_not_async(impl_item.span, sig.header.asyncness.node);
                     }
                 }
             }
-            ItemKind::Impl(unsafety, polarity, defaultness, _, None, _, _) => {
+            ItemKind::Impl {
+                unsafety,
+                polarity,
+                defaultness,
+                generics: _,
+                of_trait: None,
+                self_ty: _,
+                items: _,
+            } => {
                 self.invalid_visibility(
                     &item.vis,
                     Some("place qualifiers on individual impl items instead"),

diff --git a/src/librustc_ast_passes/feature_gate.rs b/src/librustc_ast_passes/feature_gate.rs
@@ -339,7 +339,7 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
                 }
             }
 
-            ast::ItemKind::Impl(_, polarity, defaultness, ..) => {
+            ast::ItemKind::Impl { polarity, defaultness, .. } => {
                 if polarity == ast::ImplPolarity::Negative {
                     gate_feature_post!(
                         &self,

diff --git a/src/librustc_builtin_macros/deriving/generic/mod.rs b/src/librustc_builtin_macros/deriving/generic/mod.rs
@@ -705,15 +705,15 @@ impl<'a> TraitDef<'a> {
             self.span,
             Ident::invalid(),
             a,
-            ast::ItemKind::Impl(
+            ast::ItemKind::Impl {
                 unsafety,
-                ast::ImplPolarity::Positive,
-                ast::Defaultness::Final,
-                trait_generics,
-                opt_trait_ref,
-                self_type,
-                methods.into_iter().chain(associated_types).collect(),
-            ),
+                polarity: ast::ImplPolarity::Positive,
+                defaultness: ast::Defaultness::Final,
+                generics: trait_generics,
+                of_trait: opt_trait_ref,
+                self_ty: self_type,
+                items: methods.into_iter().chain(associated_types).collect(),
+            },
         )
     }
 

diff --git a/src/librustc_builtin_macros/deriving/mod.rs b/src/librustc_builtin_macros/deriving/mod.rs
@@ -156,15 +156,15 @@ fn inject_impl_of_structural_trait(
         span,
         ast::Ident::invalid(),
         attrs,
-        ItemKind::Impl(
-            ast::Unsafety::Normal,
-            ast::ImplPolarity::Positive,
-            ast::Defaultness::Final,
+        ItemKind::Impl {
+            unsafety: ast::Unsafety::Normal,
+            polarity: ast::ImplPolarity::Positive,
+            defaultness: ast::Defaultness::Final,
             generics,
-            Some(trait_ref),
-            self_type,
-            Vec::new(),
-        ),
+            of_trait: Some(trait_ref),
+            self_ty: self_type,
+            items: Vec::new(),
+        },
     );
 
     push(Annotatable::Item(newitem));

diff --git a/src/librustc_error_codes/error_codes/E0198.md b/src/librustc_error_codes/error_codes/E0198.md
@@ -1,17 +1,18 @@
-A negative implementation is one that excludes a type from implementing a
-particular trait. Not being able to use a trait is always a safe operation,
-so negative implementations are always safe and never need to be marked as
-unsafe.
+A negative implementation was marked as unsafe.
 
-```compile_fail
-#![feature(optin_builtin_traits)]
+Erroneous code example:
 
+```compile_fail
 struct Foo;
 
-// unsafe is unnecessary
-unsafe impl !Clone for Foo { }
+unsafe impl !Clone for Foo { } // error!
 ```
 
+A negative implementation is one that excludes a type from implementing a
+particular trait. Not being able to use a trait is always a safe operation,
+so negative implementations are always safe and never need to be marked as
+unsafe.
+
 This will compile:
 
 ```ignore (ignore auto_trait future compatibility warning)

diff --git a/src/librustc_error_codes/error_codes/E0199.md b/src/librustc_error_codes/error_codes/E0199.md
@@ -1,14 +1,23 @@
+A trait implementation was marked as unsafe while the trait is safe.
+
+Erroneous code example:
+
+```compile_fail,E0199
+struct Foo;
+
+trait Bar { }
+
+unsafe impl Bar for Foo { } // error!
+```
+
 Safe traits should not have unsafe implementations, therefore marking an
 implementation for a safe trait unsafe will cause a compiler error. Removing
-the unsafe marker on the trait noted in the error will resolve this problem.
+the unsafe marker on the trait noted in the error will resolve this problem:
 
-```compile_fail,E0199
+```
 struct Foo;
 
 trait Bar { }
 
-// this won't compile because Bar is safe
-unsafe impl Bar for Foo { }
-// this will compile
-impl Bar for Foo { }
+impl Bar for Foo { } // ok!
 ```
diff --git a/src/librustc_errors/emitter.rs b/src/librustc_errors/emitter.rs
@@ -1476,6 +1476,15 @@ impl EmitterWriter {
             None => return Ok(()),
         };
 
+        // Render the replacements for each suggestion
+        let suggestions = suggestion.splice_lines(&**sm);
+
+        if suggestions.is_empty() {
+            // Suggestions coming from macros can have malformed spans. This is a heavy handed
+            // approach to avoid ICEs by ignoring the suggestion outright.
+            return Ok(());
+        }
+
         let mut buffer = StyledBuffer::new();
 
         // Render the suggestion message
@@ -1492,9 +1501,6 @@ impl EmitterWriter {
             Some(Style::HeaderMsg),
         );
 
-        // Render the replacements for each suggestion
-        let suggestions = suggestion.splice_lines(&**sm);
-
         let mut row_num = 2;
         let mut notice_capitalization = false;
         for (complete, parts, only_capitalization) in suggestions.iter().take(MAX_SUGGESTIONS) {
@@ -1505,7 +1511,9 @@ impl EmitterWriter {
             let show_underline = !(parts.len() == 1 && parts[0].snippet.trim() == complete.trim())
                 && complete.lines().count() == 1;
 
-            let lines = sm.span_to_lines(parts[0].span).unwrap();
+            let lines = sm
+                .span_to_lines(parts[0].span)
+                .expect("span_to_lines failed when emitting suggestion");
 
             assert!(!lines.lines.is_empty());