1 use crate::deriving::path_std;
2 use crate::deriving::generic::*;
3 use crate::deriving::generic::ty::*;
5 use syntax::ast::{self, Expr, GenericArg, Generics, ItemKind, MetaItem, VariantData};
7 use syntax::ext::base::{Annotatable, ExtCtxt};
9 use syntax::symbol::{kw, sym, Symbol};
12 pub fn expand_deriving_clone(cx: &mut ExtCtxt<'_>,
16 push: &mut dyn FnMut(Annotatable)) {
17 // check if we can use a short form
19 // the short form is `fn clone(&self) -> Self { *self }`
21 // we can use the short form if:
22 // - the item is Copy (unfortunately, all we can check is whether it's also deriving Copy)
23 // - there are no generic parameters (after specialization this limitation can be removed)
24 // if we used the short form with generics, we'd have to bound the generics with
25 // Clone + Copy, and then there'd be no Clone impl at all if the user fills in something
26 // that is Clone but not Copy. and until specialization we can't write both impls.
27 // - the item is a union with Copy fields
28 // Unions with generic parameters still can derive Clone because they require Copy
29 // for deriving, Clone alone is not enough.
30 // Whever Clone is implemented for fields is irrelevant so we don't assert it.
35 Annotatable::Item(ref annitem) => {
37 ItemKind::Struct(_, Generics { ref params, .. }) |
38 ItemKind::Enum(_, Generics { ref params, .. }) => {
39 if attr::contains_name(&annitem.attrs, sym::rustc_copy_clone_marker) &&
40 !params.iter().any(|param| match param.kind {
41 ast::GenericParamKind::Type { .. } => true,
47 substructure = combine_substructure(Box::new(|c, s, sub| {
48 cs_clone_shallow("Clone", c, s, sub, false)
53 substructure = combine_substructure(Box::new(|c, s, sub| {
54 cs_clone("Clone", c, s, sub)
58 ItemKind::Union(..) => {
59 bounds = vec![Literal(path_std!(cx, marker::Copy))];
61 substructure = combine_substructure(Box::new(|c, s, sub| {
62 cs_clone_shallow("Clone", c, s, sub, true)
68 substructure = combine_substructure(Box::new(|c, s, sub| {
69 cs_clone("Clone", c, s, sub)
75 _ => cx.span_bug(span, "`#[derive(Clone)]` on trait item or impl item"),
78 let inline = cx.meta_word(span, sym::inline);
79 let attrs = vec![cx.attribute(inline)];
80 let trait_def = TraitDef {
82 attributes: Vec::new(),
83 path: path_std!(cx, clone::Clone),
84 additional_bounds: bounds,
85 generics: LifetimeBounds::empty(),
87 supports_unions: true,
88 methods: vec![MethodDef {
90 generics: LifetimeBounds::empty(),
91 explicit_self: borrowed_explicit_self(),
96 unify_fieldless_variants: false,
97 combine_substructure: substructure,
99 associated_types: Vec::new(),
102 trait_def.expand_ext(cx, mitem, item, push, is_shallow)
105 fn cs_clone_shallow(name: &str,
106 cx: &mut ExtCtxt<'_>,
108 substr: &Substructure<'_>,
111 fn assert_ty_bounds(cx: &mut ExtCtxt<'_>, stmts: &mut Vec<ast::Stmt>,
112 ty: P<ast::Ty>, span: Span, helper_name: &str) {
113 // Generate statement `let _: helper_name<ty>;`,
114 // set the expn ID so we can use the unstable struct.
115 let span = span.with_ctxt(cx.backtrace());
116 let assert_path = cx.path_all(span, true,
117 cx.std_path(&[sym::clone, Symbol::intern(helper_name)]),
118 vec![GenericArg::Type(ty)], vec![]);
119 stmts.push(cx.stmt_let_type_only(span, cx.ty_path(assert_path)));
121 fn process_variant(cx: &mut ExtCtxt<'_>, stmts: &mut Vec<ast::Stmt>, variant: &VariantData) {
122 for field in variant.fields() {
123 // let _: AssertParamIsClone<FieldTy>;
124 assert_ty_bounds(cx, stmts, field.ty.clone(), field.span, "AssertParamIsClone");
128 let mut stmts = Vec::new();
130 // let _: AssertParamIsCopy<Self>;
132 cx.ty_path(cx.path_ident(trait_span, ast::Ident::with_empty_ctxt(kw::SelfUpper)));
133 assert_ty_bounds(cx, &mut stmts, self_ty, trait_span, "AssertParamIsCopy");
135 match *substr.fields {
136 StaticStruct(vdata, ..) => {
137 process_variant(cx, &mut stmts, vdata);
139 StaticEnum(enum_def, ..) => {
140 for variant in &enum_def.variants {
141 process_variant(cx, &mut stmts, &variant.node.data);
144 _ => cx.span_bug(trait_span, &format!("unexpected substructure in \
145 shallow `derive({})`", name))
148 stmts.push(cx.stmt_expr(cx.expr_deref(trait_span, cx.expr_self(trait_span))));
149 cx.expr_block(cx.block(trait_span, stmts))
152 fn cs_clone(name: &str,
153 cx: &mut ExtCtxt<'_>,
155 substr: &Substructure<'_>)
159 let fn_path = cx.std_path(&[sym::clone, sym::Clone, sym::clone]);
160 let subcall = |cx: &mut ExtCtxt<'_>, field: &FieldInfo<'_>| {
161 let args = vec![cx.expr_addr_of(field.span, field.self_.clone())];
162 cx.expr_call_global(field.span, fn_path.clone(), args)
166 match *substr.fields {
167 Struct(vdata_, ref af) => {
168 ctor_path = cx.path(trait_span, vec![substr.type_ident]);
172 EnumMatching(.., variant, ref af) => {
173 ctor_path = cx.path(trait_span, vec![substr.type_ident, variant.node.ident]);
175 vdata = &variant.node.data;
177 EnumNonMatchingCollapsed(..) => {
178 cx.span_bug(trait_span,
179 &format!("non-matching enum variants in \
183 StaticEnum(..) | StaticStruct(..) => {
184 cx.span_bug(trait_span, &format!("static method in `derive({})`", name))
189 VariantData::Struct(..) => {
190 let fields = all_fields.iter()
192 let ident = match field.name {
195 cx.span_bug(trait_span,
196 &format!("unnamed field in normal struct in \
201 let call = subcall(cx, field);
202 cx.field_imm(field.span, ident, call)
204 .collect::<Vec<_>>();
206 cx.expr_struct(trait_span, ctor_path, fields)
208 VariantData::Tuple(..) => {
209 let subcalls = all_fields.iter().map(|f| subcall(cx, f)).collect();
210 let path = cx.expr_path(ctor_path);
211 cx.expr_call(trait_span, path, subcalls)
213 VariantData::Unit(..) => cx.expr_path(ctor_path),