ast: Implement `TryFrom<ItemKind>` for associated and foreign items

[rust.git] / src / librustc_parse / parser / item.rs

diff --git a/src/librustc_parse/parser/item.rs b/src/librustc_parse/parser/item.rs
index d00d9fc72bfff80de4282ff36811a05e4e512d08..08e74034e86a1be9920b7f9c7b20cc1572b604e6 100644 (file)
--- a/src/librustc_parse/parser/item.rs
+++ b/src/librustc_parse/parser/item.rs
@@ -4,22 +4,27 @@
 
 use crate::maybe_whole;
 
+use rustc_ast::ast::{self, AttrStyle, AttrVec, Attribute, Ident, DUMMY_NODE_ID};
+use rustc_ast::ast::{AssocItem, AssocItemKind, ForeignItemKind, Item, ItemKind};
+use rustc_ast::ast::{
+    Async, Const, Defaultness, IsAuto, PathSegment, Unsafe, UseTree, UseTreeKind,
+};
+use rustc_ast::ast::{
+    BindingMode, Block, FnDecl, FnSig, Mac, MacArgs, MacDelimiter, Param, SelfKind,
+};
+use rustc_ast::ast::{EnumDef, Generics, StructField, TraitRef, Ty, TyKind, Variant, VariantData};
+use rustc_ast::ast::{FnHeader, ForeignItem, Mutability, Visibility, VisibilityKind};
+use rustc_ast::ptr::P;
+use rustc_ast::token;
+use rustc_ast::tokenstream::{DelimSpan, TokenStream, TokenTree};
 use rustc_ast_pretty::pprust;
 use rustc_errors::{struct_span_err, Applicability, PResult, StashKey};
 use rustc_span::edition::Edition;
 use rustc_span::source_map::{self, Span};
 use rustc_span::symbol::{kw, sym, Symbol};
-use syntax::ast::{self, AttrStyle, AttrVec, Attribute, Ident, DUMMY_NODE_ID};
-use syntax::ast::{AssocItem, AssocItemKind, ForeignItemKind, Item, ItemKind};
-use syntax::ast::{Async, Const, Defaultness, IsAuto, PathSegment, Unsafe, UseTree, UseTreeKind};
-use syntax::ast::{BindingMode, Block, FnDecl, FnSig, Mac, MacArgs, MacDelimiter, Param, SelfKind};
-use syntax::ast::{EnumDef, Generics, StructField, TraitRef, Ty, TyKind, Variant, VariantData};
-use syntax::ast::{FnHeader, ForeignItem, Mutability, Visibility, VisibilityKind};
-use syntax::ptr::P;
-use syntax::token;
-use syntax::tokenstream::{DelimSpan, TokenStream, TokenTree};
 
 use log::debug;
+use std::convert::TryFrom;
 use std::mem;
 
 pub(super) type ItemInfo = (Ident, ItemKind);
@@ -643,16 +648,16 @@ pub fn parse_trait_item(&mut self) -> PResult<'a, Option<Option<P<AssocItem>>>>
     /// Parses associated items.
     fn parse_assoc_item(&mut self, req_name: ReqName) -> PResult<'a, Option<Option<P<AssocItem>>>> {
         Ok(self.parse_item_(req_name)?.map(|Item { attrs, id, span, vis, ident, kind, tokens }| {
-            let kind = match kind {
-                ItemKind::Mac(a) => AssocItemKind::Macro(a),
-                ItemKind::Fn(a, b, c, d) => AssocItemKind::Fn(a, b, c, d),
-                ItemKind::TyAlias(a, b, c, d) => AssocItemKind::TyAlias(a, b, c, d),
-                ItemKind::Const(a, b, c) => AssocItemKind::Const(a, b, c),
-                ItemKind::Static(a, _, b) => {
-                    self.struct_span_err(span, "associated `static` items are not allowed").emit();
-                    AssocItemKind::Const(Defaultness::Final, a, b)
-                }
-                _ => return self.error_bad_item_kind(span, &kind, "`trait`s or `impl`s"),
+            let kind = match AssocItemKind::try_from(kind) {
+                Ok(kind) => kind,
+                Err(kind) => match kind {
+                    ItemKind::Static(a, _, b) => {
+                        self.struct_span_err(span, "associated `static` items are not allowed")
+                            .emit();
+                        AssocItemKind::Const(Defaultness::Final, a, b)
+                    }
+                    _ => return self.error_bad_item_kind(span, &kind, "`trait`s or `impl`s"),
+                },
             };
             Some(P(Item { attrs, id, span, vis, ident, kind, tokens }))
         }))
@@ -829,16 +834,15 @@ fn parse_item_foreign_mod(&mut self, attrs: &mut Vec<Attribute>) -> PResult<'a,
     /// Parses a foreign item (one in an `extern { ... }` block).
     pub fn parse_foreign_item(&mut self) -> PResult<'a, Option<Option<P<ForeignItem>>>> {
         Ok(self.parse_item_(|_| true)?.map(|Item { attrs, id, span, vis, ident, kind, tokens }| {
-            let kind = match kind {
-                ItemKind::Mac(a) => ForeignItemKind::Macro(a),
-                ItemKind::Fn(a, b, c, d) => ForeignItemKind::Fn(a, b, c, d),
-                ItemKind::TyAlias(a, b, c, d) => ForeignItemKind::TyAlias(a, b, c, d),
-                ItemKind::Static(a, b, c) => ForeignItemKind::Static(a, b, c),
-                ItemKind::Const(_, a, b) => {
-                    self.error_on_foreign_const(span, ident);
-                    ForeignItemKind::Static(a, Mutability::Not, b)
-                }
-                _ => return self.error_bad_item_kind(span, &kind, "`extern` blocks"),
+            let kind = match ForeignItemKind::try_from(kind) {
+                Ok(kind) => kind,
+                Err(kind) => match kind {
+                    ItemKind::Const(_, a, b) => {
+                        self.error_on_foreign_const(span, ident);
+                        ForeignItemKind::Static(a, Mutability::Not, b)
+                    }
+                    _ => return self.error_bad_item_kind(span, &kind, "`extern` blocks"),
+                },
             };
             Some(P(Item { attrs, id, span, vis, ident, kind, tokens }))
         }))