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use crate::deriving::generic::ty::*;
use crate::deriving::generic::*;
use crate::deriving::path_std;
use rustc_ast::ptr::P;
use rustc_ast::{self as ast, Expr, Generics, ItemKind, MetaItem, VariantData};
use rustc_expand::base::{Annotatable, ExtCtxt};
use rustc_span::symbol::{kw, sym, Ident};
use rustc_span::Span;
pub fn expand_deriving_clone(
cx: &mut ExtCtxt<'_>,
span: Span,
mitem: &MetaItem,
item: &Annotatable,
push: &mut dyn FnMut(Annotatable),
) {
// check if we can use a short form
//
// the short form is `fn clone(&self) -> Self { *self }`
//
// we can use the short form if:
// - the item is Copy (unfortunately, all we can check is whether it's also deriving Copy)
// - there are no generic parameters (after specialization this limitation can be removed)
// if we used the short 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. and until specialization we can't write both impls.
// - the item is a union with Copy fields
// Unions with generic parameters still can derive Clone because they require Copy
// for deriving, Clone alone is not enough.
// Wherever Clone is implemented for fields is irrelevant so we don't assert it.
let bounds;
let substructure;
let is_shallow;
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_shallow = true;
substructure = combine_substructure(Box::new(|c, s, sub| {
cs_clone_shallow("Clone", c, s, sub, false)
}));
} else {
bounds = vec![];
is_shallow = false;
substructure =
combine_substructure(Box::new(|c, s, sub| cs_clone("Clone", c, s, sub)));
}
}
ItemKind::Union(..) => {
bounds = vec![Literal(path_std!(marker::Copy))];
is_shallow = true;
substructure = combine_substructure(Box::new(|c, s, sub| {
cs_clone_shallow("Clone", c, s, sub, true)
}));
}
_ => {
bounds = vec![];
is_shallow = false;
substructure =
combine_substructure(Box::new(|c, s, sub| cs_clone("Clone", c, s, sub)));
}
},
_ => cx.span_bug(span, "`#[derive(Clone)]` on trait item or impl item"),
}
let inline = cx.meta_word(span, sym::inline);
let attrs = vec![cx.attribute(inline)];
let trait_def = TraitDef {
span,
attributes: Vec::new(),
path: path_std!(clone::Clone),
additional_bounds: bounds,
generics: Bounds::empty(),
is_unsafe: false,
supports_unions: true,
methods: vec![MethodDef {
name: sym::clone,
generics: Bounds::empty(),
explicit_self: borrowed_explicit_self(),
args: Vec::new(),
ret_ty: Self_,
attributes: attrs,
is_unsafe: false,
unify_fieldless_variants: false,
combine_substructure: substructure,
}],
associated_types: Vec::new(),
};
trait_def.expand_ext(cx, mitem, item, push, is_shallow)
}
fn cs_clone_shallow(
name: &str,
cx: &mut ExtCtxt<'_>,
trait_span: Span,
substr: &Substructure<'_>,
is_union: bool,
) -> P<Expr> {
fn process_variant(cx: &mut ExtCtxt<'_>, stmts: &mut Vec<ast::Stmt>, variant: &VariantData) {
for field in variant.fields() {
// let _: AssertParamIsClone<FieldTy>;
super::assert_ty_bounds(
cx,
stmts,
field.ty.clone(),
field.span,
&[sym::clone, sym::AssertParamIsClone],
);
}
}
let mut stmts = Vec::new();
if is_union {
// 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(cx, &mut stmts, vdata);
}
StaticEnum(enum_def, ..) => {
for variant in &enum_def.variants {
process_variant(cx, &mut stmts, &variant.data);
}
}
_ => cx.span_bug(
trait_span,
&format!("unexpected substructure in shallow `derive({})`", name),
),
}
}
stmts.push(cx.stmt_expr(cx.expr_deref(trait_span, cx.expr_self(trait_span))));
cx.expr_block(cx.block(trait_span, stmts))
}
fn cs_clone(
name: &str,
cx: &mut ExtCtxt<'_>,
trait_span: Span,
substr: &Substructure<'_>,
) -> P<Expr> {
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![cx.expr_addr_of(field.span, field.self_.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;
}
EnumNonMatchingCollapsed(..) => {
cx.span_bug(trait_span, &format!("non-matching enum variants in `derive({})`", name,))
}
StaticEnum(..) | StaticStruct(..) => {
cx.span_bug(trait_span, &format!("associated function in `derive({})`", name))
}
}
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),
}
}
|
