rustc_builtin_macros/deriving/
mod.rs

1//! The compiler code necessary to implement the `#[derive]` extensions.
2
3use rustc_ast as ast;
4use rustc_ast::{GenericArg, MetaItem};
5use rustc_expand::base::{Annotatable, ExpandResult, ExtCtxt, MultiItemModifier};
6use rustc_span::{Span, Symbol, sym};
7use thin_vec::{ThinVec, thin_vec};
8
9macro path_local($x:ident) {
10    generic::ty::Path::new_local(sym::$x)
11}
12
13macro pathvec_std($($rest:ident)::+) {{
14    vec![ $( sym::$rest ),+ ]
15}}
16
17macro path_std($($x:tt)*) {
18    generic::ty::Path::new( pathvec_std!( $($x)* ) )
19}
20
21pub(crate) mod bounds;
22pub(crate) mod clone;
23pub(crate) mod coerce_pointee;
24pub(crate) mod debug;
25pub(crate) mod default;
26pub(crate) mod from;
27pub(crate) mod hash;
28pub(crate) mod reborrow;
29
30#[path = "cmp/eq.rs"]
31pub(crate) mod eq;
32#[path = "cmp/ord.rs"]
33pub(crate) mod ord;
34#[path = "cmp/partial_eq.rs"]
35pub(crate) mod partial_eq;
36#[path = "cmp/partial_ord.rs"]
37pub(crate) mod partial_ord;
38
39pub(crate) mod generic;
40
41pub(crate) type BuiltinDeriveFn =
42    fn(&ExtCtxt<'_>, Span, &MetaItem, &Annotatable, &mut dyn FnMut(Annotatable), bool);
43
44pub(crate) struct BuiltinDerive(pub(crate) BuiltinDeriveFn);
45
46impl MultiItemModifier for BuiltinDerive {
47    fn expand(
48        &self,
49        ecx: &mut ExtCtxt<'_>,
50        span: Span,
51        meta_item: &MetaItem,
52        item: Annotatable,
53        is_derive_const: bool,
54    ) -> ExpandResult<Vec<Annotatable>, Annotatable> {
55        // FIXME: Built-in derives often forget to give spans contexts,
56        // so we are doing it here in a centralized way.
57        let span = ecx.with_def_site_ctxt(span);
58        let mut items = Vec::new();
59        match item {
60            Annotatable::Stmt(stmt) => {
61                if let ast::StmtKind::Item(item) = stmt.kind {
62                    (self.0)(
63                        ecx,
64                        span,
65                        meta_item,
66                        &Annotatable::Item(item),
67                        &mut |a| {
68                            // Cannot use 'ecx.stmt_item' here, because we need to pass 'ecx'
69                            // to the function
70                            items.push(Annotatable::Stmt(Box::new(ast::Stmt {
71                                id: ast::DUMMY_NODE_ID,
72                                kind: ast::StmtKind::Item(a.expect_item()),
73                                span,
74                            })));
75                        },
76                        is_derive_const,
77                    );
78                } else {
79                    {
    ::core::panicking::panic_fmt(format_args!("internal error: entered unreachable code: {0}",
            format_args!("should have already errored on non-item statement")));
}unreachable!("should have already errored on non-item statement")
80                }
81            }
82            _ => {
83                (self.0)(ecx, span, meta_item, &item, &mut |a| items.push(a), is_derive_const);
84            }
85        }
86        ExpandResult::Ready(items)
87    }
88}
89
90/// Constructs an expression that calls an intrinsic
91fn call_intrinsic(
92    cx: &ExtCtxt<'_>,
93    span: Span,
94    intrinsic: Symbol,
95    args: ThinVec<Box<ast::Expr>>,
96) -> Box<ast::Expr> {
97    let span = cx.with_def_site_ctxt(span);
98    let path = cx.std_path(&[sym::intrinsics, intrinsic]);
99    cx.expr_call_global(span, path, args)
100}
101
102/// Constructs an expression that calls the `unreachable` intrinsic.
103fn call_unreachable(cx: &ExtCtxt<'_>, span: Span) -> Box<ast::Expr> {
104    let span = cx.with_def_site_ctxt(span);
105    let path = cx.std_path(&[sym::intrinsics, sym::unreachable]);
106    let call = cx.expr_call_global(span, path, ThinVec::new());
107
108    cx.expr_block(Box::new(ast::Block {
109        stmts: {
    let len = [()].len();
    let mut vec = ::thin_vec::ThinVec::with_capacity(len);
    vec.push(cx.stmt_expr(call));
    vec
}thin_vec![cx.stmt_expr(call)],
110        id: ast::DUMMY_NODE_ID,
111        rules: ast::BlockCheckMode::Unsafe(ast::CompilerGenerated),
112        span,
113    }))
114}
115
116fn assert_ty_bounds(
117    cx: &ExtCtxt<'_>,
118    stmts: &mut ThinVec<ast::Stmt>,
119    ty: Box<ast::Ty>,
120    span: Span,
121    assert_path: &[Symbol],
122) {
123    // Generate statement `let _: assert_path<ty>;`.
124    let span = cx.with_def_site_ctxt(span);
125    let assert_path = cx.path_all(span, true, cx.std_path(assert_path), ::alloc::boxed::box_assume_init_into_vec_unsafe(::alloc::intrinsics::write_box_via_move(::alloc::boxed::Box::new_uninit(),
        [GenericArg::Type(ty)]))vec![GenericArg::Type(ty)]);
126    stmts.push(cx.stmt_let_type_only(span, cx.ty_path(assert_path)));
127}
rustc_builtin_macros/deriving/mod.rs

rustc_builtin_macros/deriving/
mod.rs
