rustc_builtin_macros/deriving/
hash.rs1use rustc_ast::{MetaItem, Mutability, Safety};
2use rustc_expand::base::{Annotatable, ExtCtxt};
3use rustc_span::{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_hash(
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 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::hash, sym::Hash]))
})path_std!(hash::Hash);
19
20 let typaram = sym::__H;
21
22 let arg = Path::new_local(typaram);
23 let hash_trait_def = TraitDef {
24 span,
25 path,
26 skip_path_as_bound: false,
27 needs_copy_as_bound_if_packed: true,
28 additional_bounds: SmallVec::new(),
29 supports_unions: false,
30 methods: {
let count = 0usize + 1usize;
let mut vec = ::smallvec::SmallVec::new();
if count <= vec.inline_size() {
vec.push(MethodDef {
name: sym::hash,
generics: Bounds {
bounds: ::alloc::boxed::box_assume_init_into_vec_unsafe(::alloc::intrinsics::write_box_via_move(::alloc::boxed::Box::new_uninit(),
[(typaram,
::alloc::boxed::box_assume_init_into_vec_unsafe(::alloc::intrinsics::write_box_via_move(::alloc::boxed::Box::new_uninit(),
[generic::ty::Path::new({
::alloc::boxed::box_assume_init_into_vec_unsafe(::alloc::intrinsics::write_box_via_move(::alloc::boxed::Box::new_uninit(),
[sym::hash, sym::Hasher]))
})])))])),
},
explicit_self: true,
nonself_args: {
let count = 0usize + 1usize;
let mut vec = ::smallvec::SmallVec::new();
if count <= vec.inline_size() {
vec.push((Ref(Box::new(Path(arg)), Mutability::Mut),
sym::state));
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(),
[(Ref(Box::new(Path(arg)), Mutability::Mut), sym::state)])))
}
},
ret_ty: Unit,
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(hash_substructure),
});
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::hash,
generics: Bounds {
bounds: ::alloc::boxed::box_assume_init_into_vec_unsafe(::alloc::intrinsics::write_box_via_move(::alloc::boxed::Box::new_uninit(),
[(typaram,
::alloc::boxed::box_assume_init_into_vec_unsafe(::alloc::intrinsics::write_box_via_move(::alloc::boxed::Box::new_uninit(),
[generic::ty::Path::new({
::alloc::boxed::box_assume_init_into_vec_unsafe(::alloc::intrinsics::write_box_via_move(::alloc::boxed::Box::new_uninit(),
[sym::hash, sym::Hasher]))
})])))])),
},
explicit_self: true,
nonself_args: {
let count = 0usize + 1usize;
let mut vec = ::smallvec::SmallVec::new();
if count <= vec.inline_size() {
vec.push((Ref(Box::new(Path(arg)), Mutability::Mut),
sym::state));
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(),
[(Ref(Box::new(Path(arg)), Mutability::Mut), sym::state)])))
}
},
ret_ty: Unit,
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(hash_substructure),
}])))
}
}smallvec![MethodDef {
31 name: sym::hash,
32 generics: Bounds { bounds: vec![(typaram, vec![path_std!(hash::Hasher)])] },
33 explicit_self: true,
34 nonself_args: smallvec![(Ref(Box::new(Path(arg)), Mutability::Mut), sym::state)],
35 ret_ty: Unit,
36 attributes: thin_vec![cx.attr_word(sym::inline, span)],
37 fieldless_variants_strategy: FieldlessVariantsStrategy::Unify,
38 combine_substructure: combine_substructure(hash_substructure),
39 }],
40 associated_types: SmallVec::new(),
41 is_const,
42 safety: Safety::Default,
43 document: true,
44 };
45
46 hash_trait_def.expand(cx, mitem, item, push);
47}
48
49fn hash_substructure(cx: &ExtCtxt<'_>, trait_span: Span, substr: &Substructure<'_>) -> BlockOrExpr {
50 let [state_expr] = substr.nonselflike_args else {
51 cx.dcx().span_bug(trait_span, "incorrect number of arguments in `derive(Hash)`");
52 };
53 let call_hash = |span, expr| {
54 let strs = cx.std_path(&[sym::hash, sym::Hash, sym::hash]);
55 let hash_path = cx.expr_path(cx.path_global(span, strs));
56 let expr = cx.expr_call(span, hash_path, {
let len = [(), ()].len();
let mut vec = ::thin_vec::ThinVec::with_capacity(len);
vec.push(expr);
vec.push(state_expr.clone());
vec
}thin_vec![expr, state_expr.clone()]);
57 cx.stmt_expr(expr)
58 };
59
60 let (stmts, match_expr) = match substr.fields {
61 Struct(_, fields) | EnumMatching(.., fields) => {
62 let stmts =
63 fields.iter().map(|field| call_hash(field.span, field.self_expr.clone())).collect();
64 (stmts, None)
65 }
66 EnumDiscr(discr_field, match_expr) => {
67 if !discr_field.other_selflike_exprs.is_empty() {
::core::panicking::panic("assertion failed: discr_field.other_selflike_exprs.is_empty()")
};assert!(discr_field.other_selflike_exprs.is_empty());
68 let stmts = {
let len = [()].len();
let mut vec = ::thin_vec::ThinVec::with_capacity(len);
vec.push(call_hash(discr_field.span, discr_field.self_expr.clone()));
vec
}thin_vec![call_hash(discr_field.span, discr_field.self_expr.clone())];
69 (stmts, match_expr.clone())
70 }
71 _ => cx.dcx().span_bug(trait_span, "impossible substructure in `derive(Hash)`"),
72 };
73
74 BlockOrExpr::new_mixed(stmts, match_expr)
75}