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;
10 use thin_vec::thin_vec;
12 pub fn expand_deriving_eq(
17 push: &mut dyn FnMut(Annotatable),
20 let span = cx.with_def_site_ctxt(span);
21 let attrs = thin_vec![
22 cx.attr_word(sym::inline, span),
23 cx.attr_nested_word(sym::doc, sym::hidden, span),
24 cx.attr_word(sym::no_coverage, span)
26 let trait_def = TraitDef {
28 path: path_std!(cmp::Eq),
29 skip_path_as_bound: false,
30 needs_copy_as_bound_if_packed: true,
31 additional_bounds: Vec::new(),
32 supports_unions: true,
33 methods: vec![MethodDef {
34 name: sym::assert_receiver_is_total_eq,
35 generics: Bounds::empty(),
40 fieldless_variants_strategy: FieldlessVariantsStrategy::Unify,
41 combine_substructure: combine_substructure(Box::new(|a, b, c| {
42 cs_total_eq_assert(a, b, c)
45 associated_types: Vec::new(),
49 super::inject_impl_of_structural_trait(cx, span, item, path_std!(marker::StructuralEq), push);
51 trait_def.expand_ext(cx, mitem, item, push, true)
54 fn cs_total_eq_assert(
57 substr: &Substructure<'_>,
59 let mut stmts = Vec::new();
60 let mut seen_type_names = FxHashSet::default();
61 let mut process_variant = |variant: &ast::VariantData| {
62 for field in variant.fields() {
63 // This basic redundancy checking only prevents duplication of
64 // assertions like `AssertParamIsEq<Foo>` where the type is a
65 // simple name. That's enough to get a lot of cases, though.
66 if let Some(name) = field.ty.kind.is_simple_path() && !seen_type_names.insert(name) {
67 // Already produced an assertion for this type.
69 // let _: AssertParamIsEq<FieldTy>;
70 super::assert_ty_bounds(
75 &[sym::cmp, sym::AssertParamIsEq],
81 match *substr.fields {
82 StaticStruct(vdata, ..) => {
83 process_variant(vdata);
85 StaticEnum(enum_def, ..) => {
86 for variant in &enum_def.variants {
87 process_variant(&variant.data);
90 _ => cx.span_bug(trait_span, "unexpected substructure in `derive(Eq)`"),
92 BlockOrExpr::new_stmts(stmts)