83 lines
2.7 KiB
Rust
83 lines
2.7 KiB
Rust
use crate::deriving::generic::ty::*;
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use crate::deriving::generic::*;
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use crate::deriving::{path_std, pathvec_std};
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use rustc_ast::{MetaItem, Mutability};
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use rustc_expand::base::{Annotatable, ExtCtxt};
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use rustc_span::symbol::sym;
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use rustc_span::Span;
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use thin_vec::thin_vec;
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pub fn expand_deriving_hash(
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cx: &mut ExtCtxt<'_>,
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span: Span,
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mitem: &MetaItem,
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item: &Annotatable,
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push: &mut dyn FnMut(Annotatable),
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is_const: bool,
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) {
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let path = Path::new_(pathvec_std!(hash::Hash), vec![], PathKind::Std);
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let typaram = sym::__H;
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let arg = Path::new_local(typaram);
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let hash_trait_def = TraitDef {
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span,
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path,
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skip_path_as_bound: false,
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needs_copy_as_bound_if_packed: true,
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additional_bounds: Vec::new(),
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supports_unions: false,
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methods: vec![MethodDef {
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name: sym::hash,
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generics: Bounds { bounds: vec![(typaram, vec![path_std!(hash::Hasher)])] },
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explicit_self: true,
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nonself_args: vec![(Ref(Box::new(Path(arg)), Mutability::Mut), sym::state)],
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ret_ty: Unit,
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attributes: thin_vec![cx.attr_word(sym::inline, span)],
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fieldless_variants_strategy: FieldlessVariantsStrategy::Unify,
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combine_substructure: combine_substructure(Box::new(|a, b, c| {
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hash_substructure(a, b, c)
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})),
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}],
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associated_types: Vec::new(),
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is_const,
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};
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hash_trait_def.expand(cx, mitem, item, push);
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}
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fn hash_substructure(
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cx: &mut ExtCtxt<'_>,
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trait_span: Span,
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substr: &Substructure<'_>,
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) -> BlockOrExpr {
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let [state_expr] = substr.nonselflike_args else {
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cx.span_bug(trait_span, "incorrect number of arguments in `derive(Hash)`");
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};
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let call_hash = |span, expr| {
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let hash_path = {
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let strs = cx.std_path(&[sym::hash, sym::Hash, sym::hash]);
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cx.expr_path(cx.path_global(span, strs))
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};
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let expr = cx.expr_call(span, hash_path, thin_vec![expr, state_expr.clone()]);
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cx.stmt_expr(expr)
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};
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let (stmts, match_expr) = match substr.fields {
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Struct(_, fields) | EnumMatching(.., fields) => {
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let stmts =
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fields.iter().map(|field| call_hash(field.span, field.self_expr.clone())).collect();
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(stmts, None)
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}
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EnumTag(tag_field, match_expr) => {
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assert!(tag_field.other_selflike_exprs.is_empty());
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let stmts = thin_vec![call_hash(tag_field.span, tag_field.self_expr.clone())];
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(stmts, match_expr.clone())
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}
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_ => cx.span_bug(trait_span, "impossible substructure in `derive(Hash)`"),
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};
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BlockOrExpr::new_mixed(stmts, match_expr)
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}
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