1 use crate::deriving::generic::ty::*;
2 use crate::deriving::generic::*;
3 use crate::deriving::path_std;
5 use rustc_ast::ast::{self, Ident};
6 use rustc_ast::ast::{Expr, MetaItem};
8 use rustc_expand::base::{Annotatable, ExtCtxt};
9 use rustc_span::symbol::sym;
10 use rustc_span::{Span, DUMMY_SP};
12 pub fn expand_deriving_debug(
17 push: &mut dyn FnMut(Annotatable),
19 // &mut ::std::fmt::Formatter
21 Ptr(Box::new(Literal(path_std!(cx, fmt::Formatter))), Borrowed(None, ast::Mutability::Mut));
23 let trait_def = TraitDef {
25 attributes: Vec::new(),
26 path: path_std!(cx, fmt::Debug),
27 additional_bounds: Vec::new(),
28 generics: LifetimeBounds::empty(),
30 supports_unions: false,
31 methods: vec![MethodDef {
33 generics: LifetimeBounds::empty(),
34 explicit_self: borrowed_explicit_self(),
35 args: vec![(fmtr, "f")],
36 ret_ty: Literal(path_std!(cx, fmt::Result)),
37 attributes: Vec::new(),
39 unify_fieldless_variants: false,
40 combine_substructure: combine_substructure(Box::new(|a, b, c| {
41 show_substructure(a, b, c)
44 associated_types: Vec::new(),
46 trait_def.expand(cx, mitem, item, push)
49 /// We use the debug builders to do the heavy lifting here
50 fn show_substructure(cx: &mut ExtCtxt<'_>, span: Span, substr: &Substructure<'_>) -> P<Expr> {
51 // build fmt.debug_struct(<name>).field(<fieldname>, &<fieldval>)....build()
52 // or fmt.debug_tuple(<name>).field(&<fieldval>)....build()
53 // based on the "shape".
54 let (ident, vdata, fields) = match substr.fields {
55 Struct(vdata, fields) => (substr.type_ident, *vdata, fields),
56 EnumMatching(_, _, v, fields) => (v.ident, &v.data, fields),
57 EnumNonMatchingCollapsed(..) | StaticStruct(..) | StaticEnum(..) => {
58 cx.span_bug(span, "nonsensical .fields in `#[derive(Debug)]`")
62 // We want to make sure we have the ctxt set so that we can use unstable methods
63 let span = cx.with_def_site_ctxt(span);
64 let name = cx.expr_lit(span, ast::LitKind::Str(ident.name, ast::StrStyle::Cooked));
65 let builder = cx.ident_of("debug_trait_builder", span);
66 let builder_expr = cx.expr_ident(span, builder.clone());
68 let fmt = substr.nonself_args[0].clone();
70 let mut stmts = vec![];
72 ast::VariantData::Tuple(..) | ast::VariantData::Unit(..) => {
73 // tuple struct/"normal" variant
74 let expr = cx.expr_method_call(span, fmt, cx.ident_of("debug_tuple", span), vec![name]);
75 stmts.push(cx.stmt_let(span, true, builder, expr));
78 // Use double indirection to make sure this works for unsized types
79 let field = cx.expr_addr_of(field.span, field.self_.clone());
80 let field = cx.expr_addr_of(field.span, field);
82 let expr = cx.expr_method_call(
85 Ident::new(sym::field, span),
89 // Use `let _ = expr;` to avoid triggering the
90 // unused_results lint.
91 stmts.push(stmt_let_undescore(cx, span, expr));
94 ast::VariantData::Struct(..) => {
95 // normal struct/struct variant
97 cx.expr_method_call(span, fmt, cx.ident_of("debug_struct", span), vec![name]);
98 stmts.push(cx.stmt_let(DUMMY_SP, true, builder, expr));
100 for field in fields {
101 let name = cx.expr_lit(
103 ast::LitKind::Str(field.name.unwrap().name, ast::StrStyle::Cooked),
106 // Use double indirection to make sure this works for unsized types
107 let field = cx.expr_addr_of(field.span, field.self_.clone());
108 let field = cx.expr_addr_of(field.span, field);
109 let expr = cx.expr_method_call(
111 builder_expr.clone(),
112 Ident::new(sym::field, span),
115 stmts.push(stmt_let_undescore(cx, span, expr));
120 let expr = cx.expr_method_call(span, builder_expr, cx.ident_of("finish", span), vec![]);
122 stmts.push(cx.stmt_expr(expr));
123 let block = cx.block(span, stmts);
127 fn stmt_let_undescore(cx: &mut ExtCtxt<'_>, sp: Span, expr: P<ast::Expr>) -> ast::Stmt {
128 let local = P(ast::Local {
129 pat: cx.pat_wild(sp),
132 id: ast::DUMMY_NODE_ID,
134 attrs: ast::AttrVec::new(),
136 ast::Stmt { id: ast::DUMMY_NODE_ID, kind: ast::StmtKind::Local(local), span: sp }