Add constness field to ast::ItemKind::Impl

Author: ecstatic-morse

src/librustc_ast_lowering/item.rs

@@ -67,9 +67,8 @@ 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 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));
+                if let ItemKind::Impl { constness, ref of_trait, .. } = item.kind {
+                    if constness == Constness::Const {
                         this.lctx
                             .diagnostic()
                             .span_err(item.span, "const trait impls are not yet implemented");
@@ -366,6 +365,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 unsafety,
                 polarity,
                 defaultness,
+                constness: _, // TODO
                 generics: ref ast_generics,
                 of_trait: ref trait_ref,
                 self_ty: ref ty,

src/librustc_ast_passes/ast_validation.rs

@@ -616,6 +616,7 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
                 unsafety,
                 polarity,
                 defaultness: _,
+                constness: _, // TODO
                 generics: _,
                 of_trait: Some(_),
                 ref self_ty,
@@ -649,6 +650,7 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
                 unsafety,
                 polarity,
                 defaultness,
+                constness: _, // TODO
                 generics: _,
                 of_trait: None,
                 self_ty: _,

src/librustc_builtin_macros/deriving/generic/mod.rs

@@ -709,6 +709,7 @@ impl<'a> TraitDef<'a> {
                 unsafety,
                 polarity: ast::ImplPolarity::Positive,
                 defaultness: ast::Defaultness::Final,
+                constness: ast::Constness::NotConst,
                 generics: trait_generics,
                 of_trait: opt_trait_ref,
                 self_ty: self_type,

src/librustc_builtin_macros/deriving/mod.rs

@@ -160,6 +160,7 @@ fn inject_impl_of_structural_trait(
             unsafety: ast::Unsafety::Normal,
             polarity: ast::ImplPolarity::Positive,
             defaultness: ast::Defaultness::Final,
+            constness: ast::Constness::NotConst,
             generics,
             of_trait: Some(trait_ref),
             self_ty: self_type,

src/librustc_parse/parser/item.rs

@@ -638,6 +638,7 @@ impl<'a> Parser<'a> {
                     unsafety,
                     polarity,
                     defaultness,
+                    constness,
                     generics,
                     of_trait: Some(trait_ref),
                     self_ty: ty_second,
@@ -657,6 +658,7 @@ impl<'a> Parser<'a> {
                     unsafety,
                     polarity,
                     defaultness,
+                    constness,
                     generics,
                     of_trait: None,
                     self_ty: ty_first,

src/librustc_save_analysis/sig.rs

@@ -486,6 +486,7 @@ impl Sig for ast::Item {
                 unsafety,
                 polarity,
                 defaultness,
+                constness,
                 ref generics,
                 ref of_trait,
                 ref self_ty,
@@ -499,6 +500,9 @@ impl Sig for ast::Item {
                     text.push_str("unsafe ");
                 }
                 text.push_str("impl");
+                if constness == ast::Constness::Const {
+                    text.push_str(" const");
+                }
 
                 let generics_sig = generics.make(offset + text.len(), id, scx)?;
                 text.push_str(&generics_sig.text);

src/libsyntax/ast.rs

@@ -2618,6 +2618,7 @@ pub enum ItemKind {
         unsafety: Unsafety,
         polarity: ImplPolarity,
         defaultness: Defaultness,
+        constness: Constness,
         generics: Generics,
 
         /// The trait being implemented, if any.

src/libsyntax/mut_visit.rs

@@ -922,6 +922,7 @@ pub fn noop_visit_item_kind<T: MutVisitor>(kind: &mut ItemKind, vis: &mut T) {
             unsafety: _,
             polarity: _,
             defaultness: _,
+            constness: _,
             generics,
             of_trait,
             self_ty,

src/libsyntax/print/pprust.rs

@@ -1230,6 +1230,7 @@ impl<'a> State<'a> {
                 unsafety,
                 polarity,
                 defaultness,
+                constness,
                 ref generics,
                 ref of_trait,
                 ref self_ty,
@@ -1240,6 +1241,7 @@ impl<'a> State<'a> {
                 self.print_defaultness(defaultness);
                 self.print_unsafety(unsafety);
                 self.word_nbsp("impl");
+                self.print_constness(constness);
 
                 if !generics.params.is_empty() {
                     self.print_generic_params(&generics.params);
@@ -2773,6 +2775,13 @@ impl<'a> State<'a> {
         }
     }
 
+    crate fn print_constness(&mut self, s: ast::Constness) {
+        match s {
+            ast::Constness::Const => self.word_nbsp("const"),
+            ast::Constness::NotConst => {}
+        }
+    }
+
     crate fn print_is_auto(&mut self, s: ast::IsAuto) {
         match s {
             ast::IsAuto::Yes => self.word_nbsp("auto"),

src/libsyntax/visit.rs

@@ -312,6 +312,7 @@ pub fn walk_item<'a, V: Visitor<'a>>(visitor: &mut V, item: &'a Item) {
             unsafety: _,
             polarity: _,
             defaultness: _,
+            constness: _,
             ref generics,
             ref of_trait,
             ref self_ty,