rustc_builtin_macros/deriving/cmp/
eq.rs

1use rustc_ast::{self as ast, MetaItem, Safety};
2use rustc_data_structures::fx::FxHashSet;
3use rustc_expand::base::{Annotatable, ExtCtxt};
4use rustc_span::{Span, sym};
5use thin_vec::{ThinVec, thin_vec};
6
7use crate::deriving::generic::ty::*;
8use crate::deriving::generic::*;
9use crate::deriving::path_std;
10
11pub(crate) fn expand_deriving_eq(
12    cx: &ExtCtxt<'_>,
13    span: Span,
14    mitem: &MetaItem,
15    item: &Annotatable,
16    push: &mut dyn FnMut(Annotatable),
17    is_const: bool,
18) {
19    let span = cx.with_def_site_ctxt(span);
20
21    let trait_def = TraitDef {
22        span,
23        path: generic::ty::Path::new({
        ::alloc::boxed::box_assume_init_into_vec_unsafe(::alloc::intrinsics::write_box_via_move(::alloc::boxed::Box::new_uninit(),
                [sym::cmp, sym::Eq]))
    })path_std!(cmp::Eq),
24        skip_path_as_bound: false,
25        needs_copy_as_bound_if_packed: true,
26        additional_bounds: Vec::new(),
27        supports_unions: true,
28        methods: ::alloc::boxed::box_assume_init_into_vec_unsafe(::alloc::intrinsics::write_box_via_move(::alloc::boxed::Box::new_uninit(),
        [MethodDef {
                    name: sym::assert_fields_are_eq,
                    generics: Bounds::empty(),
                    explicit_self: true,
                    nonself_args: ::alloc::vec::Vec::new(),
                    ret_ty: Unit,
                    attributes: {
                        let len = [(), ()].len();
                        let mut vec = ::thin_vec::ThinVec::with_capacity(len);
                        vec.push(cx.attr_nested_word(sym::doc, sym::hidden, span));
                        vec.push(cx.attr_nested_word(sym::coverage, sym::off,
                                span));
                        vec
                    },
                    fieldless_variants_strategy: FieldlessVariantsStrategy::Unify,
                    combine_substructure: combine_substructure(Box::new(|a, b,
                                c| { cs_total_eq_assert(a, b, c) })),
                }]))vec![MethodDef {
29            name: sym::assert_fields_are_eq,
30            generics: Bounds::empty(),
31            explicit_self: true,
32            nonself_args: vec![],
33            ret_ty: Unit,
34            attributes: thin_vec![
35                cx.attr_nested_word(sym::doc, sym::hidden, span),
36                cx.attr_nested_word(sym::coverage, sym::off, span),
37            ],
38            fieldless_variants_strategy: FieldlessVariantsStrategy::Unify,
39            combine_substructure: combine_substructure(Box::new(|a, b, c| {
40                cs_total_eq_assert(a, b, c)
41            })),
42        }],
43        associated_types: Vec::new(),
44        is_const,
45        is_staged_api_crate: cx.ecfg.features.staged_api(),
46        safety: Safety::Default,
47        document: true,
48    };
49    trait_def.expand_ext(cx, mitem, item, push, true)
50}
51
52fn cs_total_eq_assert(
53    cx: &ExtCtxt<'_>,
54    trait_span: Span,
55    substr: &Substructure<'_>,
56) -> BlockOrExpr {
57    let mut stmts = ThinVec::new();
58    let mut seen_type_names = FxHashSet::default();
59    let mut process_variant = |variant: &ast::VariantData| {
60        for field in variant.fields() {
61            // This basic redundancy checking only prevents duplication of
62            // assertions like `AssertParamIsEq<Foo>` where the type is a
63            // simple name. That's enough to get a lot of cases, though.
64            if let Some(name) = field.ty.kind.is_simple_path()
65                && !seen_type_names.insert(name)
66            {
67                // Already produced an assertion for this type.
68            } else {
69                // let _: AssertParamIsEq<FieldTy>;
70                super::assert_ty_bounds(
71                    cx,
72                    &mut stmts,
73                    field.ty.clone(),
74                    field.span,
75                    &[sym::cmp, sym::AssertParamIsEq],
76                );
77            }
78        }
79    };
80
81    match *substr.fields {
82        StaticStruct(vdata, ..) => {
83            process_variant(vdata);
84        }
85        StaticEnum(enum_def, ..) => {
86            for variant in &enum_def.variants {
87                process_variant(&variant.data);
88            }
89        }
90        _ => cx.dcx().span_bug(trait_span, "unexpected substructure in `derive(Eq)`"),
91    }
92    BlockOrExpr::new_stmts(stmts)
93}
rustc_builtin_macros/deriving/cmp/eq.rs

rustc_builtin_macros/deriving/cmp/
eq.rs
