1 use crate::deriving::generic::ty::*;
2 use crate::deriving::generic::*;
3 use crate::deriving::path_std;
5 use rustc_ast::{self as ast, MetaItem};
6 use rustc_data_structures::fx::FxHashSet;
7 use rustc_expand::base::{Annotatable, ExtCtxt};
8 use rustc_span::symbol::{sym, Ident};
10 use thin_vec::thin_vec;
12 pub fn expand_deriving_eq(
17 push: &mut dyn FnMut(Annotatable),
19 let span = cx.with_def_site_ctxt(span);
20 let inline = cx.meta_word(span, sym::inline);
21 let hidden = rustc_ast::attr::mk_nested_word_item(Ident::new(sym::hidden, span));
22 let doc = rustc_ast::attr::mk_list_item(Ident::new(sym::doc, span), vec![hidden]);
23 let no_coverage = cx.meta_word(span, sym::no_coverage);
24 let attrs = thin_vec![cx.attribute(inline), cx.attribute(doc), cx.attribute(no_coverage)];
25 let trait_def = TraitDef {
27 path: path_std!(cmp::Eq),
28 additional_bounds: Vec::new(),
29 generics: Bounds::empty(),
30 supports_unions: true,
31 methods: vec![MethodDef {
32 name: sym::assert_receiver_is_total_eq,
33 generics: Bounds::empty(),
38 unify_fieldless_variants: true,
39 combine_substructure: combine_substructure(Box::new(|a, b, c| {
40 cs_total_eq_assert(a, b, c)
43 associated_types: Vec::new(),
46 super::inject_impl_of_structural_trait(cx, span, item, path_std!(marker::StructuralEq), push);
48 trait_def.expand_ext(cx, mitem, item, push, true)
51 fn cs_total_eq_assert(
54 substr: &Substructure<'_>,
56 let mut stmts = Vec::new();
57 let mut seen_type_names = FxHashSet::default();
58 let mut process_variant = |variant: &ast::VariantData| {
59 for field in variant.fields() {
60 // This basic redundancy checking only prevents duplication of
61 // assertions like `AssertParamIsEq<Foo>` where the type is a
62 // simple name. That's enough to get a lot of cases, though.
63 if let Some(name) = field.ty.kind.is_simple_path() && !seen_type_names.insert(name) {
64 // Already produced an assertion for this type.
66 // let _: AssertParamIsEq<FieldTy>;
67 super::assert_ty_bounds(
72 &[sym::cmp, sym::AssertParamIsEq],
78 match *substr.fields {
79 StaticStruct(vdata, ..) => {
80 process_variant(vdata);
82 StaticEnum(enum_def, ..) => {
83 for variant in &enum_def.variants {
84 process_variant(&variant.data);
87 _ => cx.span_bug(trait_span, "unexpected substructure in `derive(Eq)`"),
89 BlockOrExpr::new_stmts(stmts)