rustc_builtin_macros/deriving/cmp/
ord.rs

1use rustc_ast::{MetaItem, Safety};
2use rustc_expand::base::{Annotatable, ExtCtxt};
3use rustc_span::{Ident, Span, sym};
4use thin_vec::thin_vec;
5
6use crate::deriving::generic::ty::*;
7use crate::deriving::generic::*;
8use crate::deriving::path_std;
9
10pub(crate) fn expand_deriving_ord(
11    cx: &ExtCtxt<'_>,
12    span: Span,
13    mitem: &MetaItem,
14    item: &Annotatable,
15    push: &mut dyn FnMut(Annotatable),
16    is_const: bool,
17) {
18    let trait_def = TraitDef {
19        span,
20        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::Ord]))
    })path_std!(cmp::Ord),
21        skip_path_as_bound: false,
22        needs_copy_as_bound_if_packed: true,
23        additional_bounds: SmallVec::new(),
24        supports_unions: false,
25        methods: {
    let count = 0usize + 1usize;
    let mut vec = ::smallvec::SmallVec::new();
    if count <= vec.inline_size() {
        vec.push(MethodDef {
                name: sym::cmp,
                generics: Bounds::empty(),
                explicit_self: true,
                nonself_args: {
                    let count = 0usize + 1usize;
                    let mut vec = ::smallvec::SmallVec::new();
                    if count <= vec.inline_size() {
                        vec.push((self_ref(), sym::other));
                        vec
                    } else {
                        ::smallvec::SmallVec::from_vec(::alloc::boxed::box_assume_init_into_vec_unsafe(::alloc::intrinsics::write_box_via_move(::alloc::boxed::Box::new_uninit(),
                                    [(self_ref(), sym::other)])))
                    }
                },
                ret_ty: 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::Ordering]))
                        })),
                attributes: {
                    let len = [()].len();
                    let mut vec = ::thin_vec::ThinVec::with_capacity(len);
                    vec.push(cx.attr_word(sym::inline, span));
                    vec
                },
                fieldless_variants_strategy: FieldlessVariantsStrategy::Unify,
                combine_substructure: combine_substructure(cs_cmp),
            });
        vec
    } else {
        ::smallvec::SmallVec::from_vec(::alloc::boxed::box_assume_init_into_vec_unsafe(::alloc::intrinsics::write_box_via_move(::alloc::boxed::Box::new_uninit(),
                    [MethodDef {
                                name: sym::cmp,
                                generics: Bounds::empty(),
                                explicit_self: true,
                                nonself_args: {
                                    let count = 0usize + 1usize;
                                    let mut vec = ::smallvec::SmallVec::new();
                                    if count <= vec.inline_size() {
                                        vec.push((self_ref(), sym::other));
                                        vec
                                    } else {
                                        ::smallvec::SmallVec::from_vec(::alloc::boxed::box_assume_init_into_vec_unsafe(::alloc::intrinsics::write_box_via_move(::alloc::boxed::Box::new_uninit(),
                                                    [(self_ref(), sym::other)])))
                                    }
                                },
                                ret_ty: 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::Ordering]))
                                        })),
                                attributes: {
                                    let len = [()].len();
                                    let mut vec = ::thin_vec::ThinVec::with_capacity(len);
                                    vec.push(cx.attr_word(sym::inline, span));
                                    vec
                                },
                                fieldless_variants_strategy: FieldlessVariantsStrategy::Unify,
                                combine_substructure: combine_substructure(cs_cmp),
                            }])))
    }
}smallvec![MethodDef {
26            name: sym::cmp,
27            generics: Bounds::empty(),
28            explicit_self: true,
29            nonself_args: smallvec![(self_ref(), sym::other)],
30            ret_ty: Path(path_std!(cmp::Ordering)),
31            attributes: thin_vec![cx.attr_word(sym::inline, span)],
32            fieldless_variants_strategy: FieldlessVariantsStrategy::Unify,
33            combine_substructure: combine_substructure(cs_cmp),
34        }],
35        associated_types: SmallVec::new(),
36        is_const,
37        safety: Safety::Default,
38        document: true,
39    };
40
41    trait_def.expand(cx, mitem, item, push)
42}
43
44pub(crate) fn cs_cmp(cx: &ExtCtxt<'_>, span: Span, substr: &Substructure<'_>) -> BlockOrExpr {
45    let test_id = Ident::new(sym::cmp, span);
46    let equal_path = cx.path_global(span, cx.std_path(&[sym::cmp, sym::Ordering, sym::Equal]));
47    let cmp_path = cx.std_path(&[sym::cmp, sym::Ord, sym::cmp]);
48
49    // Builds:
50    //
51    // match ::core::cmp::Ord::cmp(&self.x, &other.x) {
52    //     ::std::cmp::Ordering::Equal =>
53    //         ::core::cmp::Ord::cmp(&self.y, &other.y),
54    //     cmp => cmp,
55    // }
56    let expr = cs_fold(
57        // foldr nests the if-elses correctly, leaving the first field
58        // as the outermost one, and the last as the innermost.
59        false,
60        cx,
61        span,
62        substr,
63        |cx, fold| match fold {
64            CsFold::Single(field) => {
65                let [other_expr] = &field.other_selflike_exprs[..] else {
66                    cx.dcx().span_bug(field.span, "not exactly 2 arguments in `derive(Ord)`");
67                };
68                let args = {
    let len = [(), ()].len();
    let mut vec = ::thin_vec::ThinVec::with_capacity(len);
    vec.push(field.self_expr.clone());
    vec.push(other_expr.clone());
    vec
}thin_vec![field.self_expr.clone(), other_expr.clone()];
69                cx.expr_call_global(field.span, cmp_path.clone(), args)
70            }
71            CsFold::Combine(span, expr1, expr2) => {
72                let eq_arm = cx.arm(span, cx.pat_path(span, equal_path.clone()), expr1);
73                let neq_arm =
74                    cx.arm(span, cx.pat_ident(span, test_id), cx.expr_ident(span, test_id));
75                cx.expr_match(span, expr2, {
    let len = [(), ()].len();
    let mut vec = ::thin_vec::ThinVec::with_capacity(len);
    vec.push(eq_arm);
    vec.push(neq_arm);
    vec
}thin_vec![eq_arm, neq_arm])
76            }
77            CsFold::Fieldless => cx.expr_path(equal_path.clone()),
78        },
79    );
80    BlockOrExpr::new_expr(expr)
81}
rustc_builtin_macros/deriving/cmp/ord.rs

rustc_builtin_macros/deriving/cmp/
ord.rs
