1 use syntax::{ast, attr};
2 use syntax::edition::Edition;
4 use syntax::sess::ParseSess;
5 use syntax::symbol::{Ident, Symbol, kw, sym};
6 use syntax_expand::expand::ExpansionConfig;
7 use syntax_expand::base::{ExtCtxt, Resolver};
8 use syntax_pos::DUMMY_SP;
9 use syntax_pos::hygiene::AstPass;
12 mut krate: ast::Crate,
13 resolver: &mut dyn Resolver,
15 alt_std_name: Option<Symbol>,
16 ) -> (ast::Crate, Option<Symbol>) {
17 let rust_2018 = sess.edition >= Edition::Edition2018;
19 // the first name in this list is the crate name of the crate with the prelude
20 let names: &[Symbol] = if attr::contains_name(&krate.attrs, sym::no_core) {
22 } else if attr::contains_name(&krate.attrs, sym::no_std) {
23 if attr::contains_name(&krate.attrs, sym::compiler_builtins) {
26 &[sym::core, sym::compiler_builtins]
32 let expn_id = resolver.expansion_for_ast_pass(
35 &[sym::prelude_import],
38 let span = DUMMY_SP.with_def_site_ctxt(expn_id);
39 let call_site = DUMMY_SP.with_call_site_ctxt(expn_id);
41 let ecfg = ExpansionConfig::default("std_lib_injection".to_string());
42 let cx = ExtCtxt::new(sess, ecfg, resolver);
45 // .rev() to preserve ordering above in combination with insert(0, ...)
46 for &name in names.iter().rev() {
47 let ident = if rust_2018 {
48 Ident::new(name, span)
50 Ident::new(name, call_site)
52 krate.module.items.insert(0, cx.item(
55 vec![cx.attribute(cx.meta_word(span, sym::macro_use))],
56 ast::ItemKind::ExternCrate(alt_std_name),
60 // The crates have been injected, the assumption is that the first one is
61 // the one with the prelude.
64 let import_path = if rust_2018 {
65 [name, sym::prelude, sym::v1].iter()
66 .map(|symbol| ast::Ident::new(*symbol, span)).collect()
68 [kw::PathRoot, name, sym::prelude, sym::v1].iter()
69 .map(|symbol| ast::Ident::new(*symbol, span)).collect()
72 let use_item = cx.item(
74 ast::Ident::invalid(),
75 vec![cx.attribute(cx.meta_word(span, sym::prelude_import))],
76 ast::ItemKind::Use(P(ast::UseTree {
77 prefix: cx.path(span, import_path),
78 kind: ast::UseTreeKind::Glob,
83 krate.module.items.insert(0, use_item);