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