1 use rustc_expand::base::{ExtCtxt, Resolver};
2 use rustc_expand::expand::ExpansionConfig;
3 use rustc_span::edition::Edition;
4 use rustc_span::hygiene::AstPass;
5 use rustc_span::symbol::{kw, sym, Ident, Symbol};
6 use rustc_span::DUMMY_SP;
8 use syntax::sess::ParseSess;
9 use syntax::{ast, attr};
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);
44 // .rev() to preserve ordering above in combination with insert(0, ...)
45 for &name in names.iter().rev() {
46 let ident = if rust_2018 { Ident::new(name, span) } else { Ident::new(name, call_site) };
47 krate.module.items.insert(
52 vec![cx.attribute(cx.meta_word(span, sym::macro_use))],
53 ast::ItemKind::ExternCrate(alt_std_name),
58 // The crates have been injected, the assumption is that the first one is
59 // the one with the prelude.
62 let import_path = if rust_2018 {
63 [name, sym::prelude, sym::v1].iter().map(|symbol| ast::Ident::new(*symbol, span)).collect()
65 [kw::PathRoot, name, sym::prelude, sym::v1]
67 .map(|symbol| ast::Ident::new(*symbol, span))
71 let use_item = cx.item(
73 ast::Ident::invalid(),
74 vec![cx.attribute(cx.meta_word(span, sym::prelude_import))],
75 ast::ItemKind::Use(P(ast::UseTree {
76 prefix: cx.path(span, import_path),
77 kind: ast::UseTreeKind::Glob,
82 krate.module.items.insert(0, use_item);