rust/compiler/rustc_builtin_macros/src/standard_library_imports.rs
2020-11-13 00:59:57 +03:00

86 lines
2.6 KiB
Rust

use rustc_ast as ast;
use rustc_ast::ptr::P;
use rustc_expand::base::{ExtCtxt, ResolverExpand};
use rustc_expand::expand::ExpansionConfig;
use rustc_session::Session;
use rustc_span::edition::Edition;
use rustc_span::hygiene::AstPass;
use rustc_span::symbol::{kw, sym, Ident, Symbol};
use rustc_span::DUMMY_SP;
pub fn inject(
mut krate: ast::Crate,
resolver: &mut dyn ResolverExpand,
sess: &Session,
alt_std_name: Option<Symbol>,
) -> ast::Crate {
let rust_2018 = sess.parse_sess.edition >= Edition::Edition2018;
// the first name in this list is the crate name of the crate with the prelude
let names: &[Symbol] = if sess.contains_name(&krate.attrs, sym::no_core) {
return krate;
} else if sess.contains_name(&krate.attrs, sym::no_std) {
if sess.contains_name(&krate.attrs, sym::compiler_builtins) {
&[sym::core]
} else {
&[sym::core, sym::compiler_builtins]
}
} else {
&[sym::std]
};
let expn_id = resolver.expansion_for_ast_pass(
DUMMY_SP,
AstPass::StdImports,
&[sym::prelude_import],
None,
);
let span = DUMMY_SP.with_def_site_ctxt(expn_id);
let call_site = DUMMY_SP.with_call_site_ctxt(expn_id);
let ecfg = ExpansionConfig::default("std_lib_injection".to_string());
let cx = ExtCtxt::new(sess, ecfg, resolver, None);
// .rev() to preserve ordering above in combination with insert(0, ...)
for &name in names.iter().rev() {
let ident = if rust_2018 { Ident::new(name, span) } else { Ident::new(name, call_site) };
krate.module.items.insert(
0,
cx.item(
span,
ident,
vec![cx.attribute(cx.meta_word(span, sym::macro_use))],
ast::ItemKind::ExternCrate(alt_std_name),
),
);
}
// The crates have been injected, the assumption is that the first one is
// the one with the prelude.
let name = names[0];
let import_path = if rust_2018 {
[name, sym::prelude, sym::v1].iter().map(|symbol| Ident::new(*symbol, span)).collect()
} else {
[kw::PathRoot, name, sym::prelude, sym::v1]
.iter()
.map(|symbol| Ident::new(*symbol, span))
.collect()
};
let use_item = cx.item(
span,
Ident::invalid(),
vec![cx.attribute(cx.meta_word(span, sym::prelude_import))],
ast::ItemKind::Use(P(ast::UseTree {
prefix: cx.path(span, import_path),
kind: ast::UseTreeKind::Glob,
span,
})),
);
krate.module.items.insert(0, use_item);
krate
}