1 use crate::deriving::generic::ty::*;
2 use crate::deriving::generic::*;
3 use crate::deriving::path_std;
4 use rustc_ast::{self as ast, Generics, ItemKind, MetaItem, VariantData};
5 use rustc_data_structures::fx::FxHashSet;
6 use rustc_expand::base::{Annotatable, ExtCtxt};
7 use rustc_span::symbol::{kw, sym, Ident};
9 use thin_vec::thin_vec;
11 pub fn expand_deriving_clone(
16 push: &mut dyn FnMut(Annotatable),
18 // The simple form is `fn clone(&self) -> Self { *self }`, possibly with
19 // some additional `AssertParamIsClone` assertions.
21 // We can use the simple form if either of the following are true.
22 // - The type derives Copy and there are no generic parameters. (If we
23 // used the simple form with generics, we'd have to bound the generics
24 // with Clone + Copy, and then there'd be no Clone impl at all if the
25 // user fills in something that is Clone but not Copy. After
26 // specialization we can remove this no-generics limitation.)
27 // - The item is a union. (Unions with generic parameters still can derive
28 // Clone because they require Copy for deriving, Clone alone is not
29 // enough. Whether Clone is implemented for fields is irrelevant so we
35 Annotatable::Item(ref annitem) => match annitem.kind {
36 ItemKind::Struct(_, Generics { ref params, .. })
37 | ItemKind::Enum(_, Generics { ref params, .. }) => {
38 let container_id = cx.current_expansion.id.expn_data().parent.expect_local();
39 let has_derive_copy = cx.resolver.has_derive_copy(container_id);
43 .any(|param| matches!(param.kind, ast::GenericParamKind::Type { .. }))
47 substructure = combine_substructure(Box::new(|c, s, sub| {
48 cs_clone_simple("Clone", c, s, sub, false)
54 combine_substructure(Box::new(|c, s, sub| cs_clone("Clone", c, s, sub)));
57 ItemKind::Union(..) => {
58 bounds = vec![Path(path_std!(marker::Copy))];
60 substructure = combine_substructure(Box::new(|c, s, sub| {
61 cs_clone_simple("Clone", c, s, sub, true)
64 _ => cx.span_bug(span, "`#[derive(Clone)]` on wrong item kind"),
67 _ => cx.span_bug(span, "`#[derive(Clone)]` on trait item or impl item"),
70 let inline = cx.meta_word(span, sym::inline);
71 let attrs = thin_vec![cx.attribute(inline)];
72 let trait_def = TraitDef {
74 path: path_std!(clone::Clone),
75 skip_path_as_bound: false,
76 additional_bounds: bounds,
77 supports_unions: true,
78 methods: vec![MethodDef {
80 generics: Bounds::empty(),
82 nonself_args: Vec::new(),
85 unify_fieldless_variants: false,
86 combine_substructure: substructure,
88 associated_types: Vec::new(),
91 trait_def.expand_ext(cx, mitem, item, push, is_simple)
98 substr: &Substructure<'_>,
101 let mut stmts = Vec::new();
102 let mut seen_type_names = FxHashSet::default();
103 let mut process_variant = |variant: &VariantData| {
104 for field in variant.fields() {
105 // This basic redundancy checking only prevents duplication of
106 // assertions like `AssertParamIsClone<Foo>` where the type is a
107 // simple name. That's enough to get a lot of cases, though.
108 if let Some(name) = field.ty.kind.is_simple_path() && !seen_type_names.insert(name) {
109 // Already produced an assertion for this type.
111 // let _: AssertParamIsClone<FieldTy>;
112 super::assert_ty_bounds(
117 &[sym::clone, sym::AssertParamIsClone],
124 // Just a single assertion for unions, that the union impls `Copy`.
125 // let _: AssertParamIsCopy<Self>;
126 let self_ty = cx.ty_path(cx.path_ident(trait_span, Ident::with_dummy_span(kw::SelfUpper)));
127 super::assert_ty_bounds(
132 &[sym::clone, sym::AssertParamIsCopy],
135 match *substr.fields {
136 StaticStruct(vdata, ..) => {
137 process_variant(vdata);
139 StaticEnum(enum_def, ..) => {
140 for variant in &enum_def.variants {
141 process_variant(&variant.data);
146 &format!("unexpected substructure in simple `derive({})`", name),
150 BlockOrExpr::new_mixed(stmts, Some(cx.expr_deref(trait_span, cx.expr_self(trait_span))))
155 cx: &mut ExtCtxt<'_>,
157 substr: &Substructure<'_>,
161 let fn_path = cx.std_path(&[sym::clone, sym::Clone, sym::clone]);
162 let subcall = |cx: &mut ExtCtxt<'_>, field: &FieldInfo| {
163 let args = vec![field.self_expr.clone()];
164 cx.expr_call_global(field.span, fn_path.clone(), args)
168 match *substr.fields {
169 Struct(vdata_, ref af) => {
170 ctor_path = cx.path(trait_span, vec![substr.type_ident]);
174 EnumMatching(.., variant, ref af) => {
175 ctor_path = cx.path(trait_span, vec![substr.type_ident, variant.ident]);
177 vdata = &variant.data;
179 EnumTag(..) => cx.span_bug(trait_span, &format!("enum tags in `derive({})`", name,)),
180 StaticEnum(..) | StaticStruct(..) => {
181 cx.span_bug(trait_span, &format!("associated function in `derive({})`", name))
185 let expr = match *vdata {
186 VariantData::Struct(..) => {
187 let fields = all_fields
190 let Some(ident) = field.name else {
193 &format!("unnamed field in normal struct in `derive({})`", name,),
196 let call = subcall(cx, field);
197 cx.field_imm(field.span, ident, call)
199 .collect::<Vec<_>>();
201 cx.expr_struct(trait_span, ctor_path, fields)
203 VariantData::Tuple(..) => {
204 let subcalls = all_fields.iter().map(|f| subcall(cx, f)).collect();
205 let path = cx.expr_path(ctor_path);
206 cx.expr_call(trait_span, path, subcalls)
208 VariantData::Unit(..) => cx.expr_path(ctor_path),
210 BlockOrExpr::new_expr(expr)