Remove PartialEq and Eq from the SpecialDerives.

Author: pnkfelix

src/librustc/hir/lowering/item.rs

@@ -18,7 +18,6 @@ use smallvec::SmallVec;
 use syntax::attr;
 use syntax::ast::*;
 use syntax::visit::{self, Visitor};
-use syntax::expand::SpecialDerives;
 use syntax::source_map::{respan, DesugaringKind, Spanned};
 use syntax::symbol::{kw, sym};
 use syntax_pos::Span;
@@ -227,13 +226,7 @@ impl LoweringContext<'_> {
     pub fn lower_item(&mut self, i: &Item) -> Option<hir::Item> {
         let mut ident = i.ident;
         let mut vis = self.lower_visibility(&i.vis, None);
-        let mut attrs = self.lower_attrs_extendable(&i.attrs);
-        if self.resolver.has_derives(i.id, SpecialDerives::PARTIAL_EQ | SpecialDerives::EQ) {
-            // Add `#[structural_match]` if the item derived both `PartialEq` and `Eq`.
-            let ident = Ident::new(sym::structural_match, i.span);
-            attrs.push(attr::mk_attr_outer(attr::mk_word_item(ident)));
-        }
-        let attrs = attrs.into();
+        let attrs = self.lower_attrs(&i.attrs);
 
         if let ItemKind::MacroDef(ref def) = i.kind {
             if !def.legacy || attr::contains_name(&i.attrs, sym::macro_export) {

src/librustc_resolve/lib.rs

@@ -937,8 +937,6 @@ pub struct Resolver<'a> {
     /// Some built-in derives mark items they are applied to so they are treated specially later.
     /// Derive macros cannot modify the item themselves and have to store the markers in the global
     /// context, so they attach the markers to derive container IDs using this resolver table.
-    /// FIXME: Find a way for `PartialEq` and `Eq` to emulate `#[structural_match]`
-    /// by marking the produced impls rather than the original items.
     special_derives: FxHashMap<ExpnId, SpecialDerives>,
     /// Parent scopes in which the macros were invoked.
     /// FIXME: `derives` are missing in these parent scopes and need to be taken from elsewhere.

src/libsyntax/expand/mod.rs

@@ -9,8 +9,6 @@ bitflags::bitflags! {
     /// Built-in derives that need some extra tracking beyond the usual macro functionality.
     #[derive(Default)]
     pub struct SpecialDerives: u8 {
-        const PARTIAL_EQ = 1 << 0;
-        const EQ         = 1 << 1;
         const COPY       = 1 << 2;
     }
 }

src/libsyntax_ext/deriving/cmp/eq.rs

@@ -3,7 +3,6 @@ use crate::deriving::generic::*;
 use crate::deriving::generic::ty::*;
 
 use syntax::ast::{self, Ident, Expr, MetaItem, GenericArg};
-use syntax::expand::SpecialDerives;
 use syntax::ptr::P;
 use syntax::symbol::{sym, Symbol};
 use syntax_expand::base::{Annotatable, ExtCtxt};
@@ -14,8 +13,6 @@ pub fn expand_deriving_eq(cx: &mut ExtCtxt<'_>,
                           mitem: &MetaItem,
                           item: &Annotatable,
                           push: &mut dyn FnMut(Annotatable)) {
-    cx.resolver.add_derives(cx.current_expansion.id.expn_data().parent, SpecialDerives::EQ);
-
     let inline = cx.meta_word(span, sym::inline);
     let hidden = syntax::attr::mk_nested_word_item(Ident::new(sym::hidden, span));
     let doc = syntax::attr::mk_list_item(Ident::new(sym::doc, span), vec![hidden]);

src/libsyntax_ext/deriving/cmp/partial_eq.rs

@@ -3,7 +3,6 @@ use crate::deriving::generic::*;
 use crate::deriving::generic::ty::*;
 
 use syntax::ast::{BinOpKind, Expr, MetaItem};
-use syntax::expand::SpecialDerives;
 use syntax::ptr::P;
 use syntax::symbol::sym;
 use syntax_expand::base::{Annotatable, ExtCtxt};
@@ -14,8 +13,6 @@ pub fn expand_deriving_partial_eq(cx: &mut ExtCtxt<'_>,
                                   mitem: &MetaItem,
                                   item: &Annotatable,
                                   push: &mut dyn FnMut(Annotatable)) {
-    cx.resolver.add_derives(cx.current_expansion.id.expn_data().parent, SpecialDerives::PARTIAL_EQ);
-
     // structures are equal if all fields are equal, and non equal, if
     // any fields are not equal or if the enum variants are different
     fn cs_op(cx: &mut ExtCtxt<'_>,