1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
|
use crate::deriving::generic::ty::*;
use crate::deriving::generic::*;
use crate::deriving::path_std;
use rustc_ast::{self as ast, Generics, ItemKind, MetaItem, VariantData};
use rustc_data_structures::fx::FxHashSet;
use rustc_expand::base::{Annotatable, ExtCtxt};
use rustc_span::symbol::{kw, sym, Ident};
use rustc_span::Span;
use thin_vec::thin_vec;
pub fn expand_deriving_clone(
cx: &mut ExtCtxt<'_>,
span: Span,
mitem: &MetaItem,
item: &Annotatable,
push: &mut dyn FnMut(Annotatable),
) {
// The simple form is `fn clone(&self) -> Self { *self }`, possibly with
// some additional `AssertParamIsClone` assertions.
//
// We can use the simple form if either of the following are true.
// - The type derives Copy and there are no generic parameters. (If we
// used the simple form with generics, we'd have to bound the generics
// with Clone + Copy, and then there'd be no Clone impl at all if the
// user fills in something that is Clone but not Copy. After
// specialization we can remove this no-generics limitation.)
// - The item is a union. (Unions with generic parameters still can derive
// Clone because they require Copy for deriving, Clone alone is not
// enough. Whether Clone is implemented for fields is irrelevant so we
// don't assert it.)
let bounds;
let substructure;
let is_simple;
match *item {
Annotatable::Item(ref annitem) => match annitem.kind {
ItemKind::Struct(_, Generics { ref params, .. })
| ItemKind::Enum(_, Generics { ref params, .. }) => {
let container_id = cx.current_expansion.id.expn_data().parent.expect_local();
let has_derive_copy = cx.resolver.has_derive_copy(container_id);
if has_derive_copy
&& !params
.iter()
.any(|param| matches!(param.kind, ast::GenericParamKind::Type { .. }))
{
bounds = vec![];
is_simple = true;
substructure = combine_substructure(Box::new(|c, s, sub| {
cs_clone_simple("Clone", c, s, sub, false)
}));
} else {
bounds = vec![];
is_simple = false;
substructure =
combine_substructure(Box::new(|c, s, sub| cs_clone("Clone", c, s, sub)));
}
}
ItemKind::Union(..) => {
bounds = vec![Path(path_std!(marker::Copy))];
is_simple = true;
substructure = combine_substructure(Box::new(|c, s, sub| {
cs_clone_simple("Clone", c, s, sub, true)
}));
}
_ => cx.span_bug(span, "`#[derive(Clone)]` on wrong item kind"),
},
_ => cx.span_bug(span, "`#[derive(Clone)]` on trait item or impl item"),
}
let inline = cx.meta_word(span, sym::inline);
let attrs = thin_vec![cx.attribute(inline)];
let trait_def = TraitDef {
span,
path: path_std!(clone::Clone),
skip_path_as_bound: false,
additional_bounds: bounds,
generics: Bounds::empty(),
supports_unions: true,
methods: vec![MethodDef {
name: sym::clone,
generics: Bounds::empty(),
explicit_self: true,
nonself_args: Vec::new(),
ret_ty: Self_,
attributes: attrs,
unify_fieldless_variants: false,
combine_substructure: substructure,
}],
associated_types: Vec::new(),
};
trait_def.expand_ext(cx, mitem, item, push, is_simple)
}
fn cs_clone_simple(
name: &str,
cx: &mut ExtCtxt<'_>,
trait_span: Span,
substr: &Substructure<'_>,
is_union: bool,
) -> BlockOrExpr {
let mut stmts = Vec::new();
let mut seen_type_names = FxHashSet::default();
let mut process_variant = |variant: &VariantData| {
for field in variant.fields() {
// This basic redundancy checking only prevents duplication of
// assertions like `AssertParamIsClone<Foo>` where the type is a
// simple name. That's enough to get a lot of cases, though.
if let Some(name) = field.ty.kind.is_simple_path() && !seen_type_names.insert(name) {
// Already produced an assertion for this type.
} else {
// let _: AssertParamIsClone<FieldTy>;
super::assert_ty_bounds(
cx,
&mut stmts,
field.ty.clone(),
field.span,
&[sym::clone, sym::AssertParamIsClone],
);
}
}
};
if is_union {
// Just a single assertion for unions, that the union impls `Copy`.
// let _: AssertParamIsCopy<Self>;
let self_ty = cx.ty_path(cx.path_ident(trait_span, Ident::with_dummy_span(kw::SelfUpper)));
super::assert_ty_bounds(
cx,
&mut stmts,
self_ty,
trait_span,
&[sym::clone, sym::AssertParamIsCopy],
);
} else {
match *substr.fields {
StaticStruct(vdata, ..) => {
process_variant(vdata);
}
StaticEnum(enum_def, ..) => {
for variant in &enum_def.variants {
process_variant(&variant.data);
}
}
_ => cx.span_bug(
trait_span,
&format!("unexpected substructure in simple `derive({})`", name),
),
}
}
BlockOrExpr::new_mixed(stmts, Some(cx.expr_deref(trait_span, cx.expr_self(trait_span))))
}
fn cs_clone(
name: &str,
cx: &mut ExtCtxt<'_>,
trait_span: Span,
substr: &Substructure<'_>,
) -> BlockOrExpr {
let ctor_path;
let all_fields;
let fn_path = cx.std_path(&[sym::clone, sym::Clone, sym::clone]);
let subcall = |cx: &mut ExtCtxt<'_>, field: &FieldInfo| {
let args = vec![field.self_expr.clone()];
cx.expr_call_global(field.span, fn_path.clone(), args)
};
let vdata;
match *substr.fields {
Struct(vdata_, ref af) => {
ctor_path = cx.path(trait_span, vec![substr.type_ident]);
all_fields = af;
vdata = vdata_;
}
EnumMatching(.., variant, ref af) => {
ctor_path = cx.path(trait_span, vec![substr.type_ident, variant.ident]);
all_fields = af;
vdata = &variant.data;
}
EnumTag(..) => cx.span_bug(trait_span, &format!("enum tags in `derive({})`", name,)),
StaticEnum(..) | StaticStruct(..) => {
cx.span_bug(trait_span, &format!("associated function in `derive({})`", name))
}
}
let expr = match *vdata {
VariantData::Struct(..) => {
let fields = all_fields
.iter()
.map(|field| {
let Some(ident) = field.name else {
cx.span_bug(
trait_span,
&format!("unnamed field in normal struct in `derive({})`", name,),
);
};
let call = subcall(cx, field);
cx.field_imm(field.span, ident, call)
})
.collect::<Vec<_>>();
cx.expr_struct(trait_span, ctor_path, fields)
}
VariantData::Tuple(..) => {
let subcalls = all_fields.iter().map(|f| subcall(cx, f)).collect();
let path = cx.expr_path(ctor_path);
cx.expr_call(trait_span, path, subcalls)
}
VariantData::Unit(..) => cx.expr_path(ctor_path),
};
BlockOrExpr::new_expr(expr)
}
|
