126 lines
4.3 KiB
Rust
126 lines
4.3 KiB
Rust
use crate::ast;
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use crate::attr;
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use crate::edition::Edition;
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use crate::ext::hygiene::{Mark, SyntaxContext};
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use crate::symbol::{Symbol, keywords};
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use crate::source_map::{ExpnInfo, MacroAttribute, dummy_spanned, hygiene, respan};
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use crate::ptr::P;
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use crate::tokenstream::TokenStream;
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use std::cell::Cell;
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use std::iter;
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use syntax_pos::{DUMMY_SP, Span};
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/// Craft a span that will be ignored by the stability lint's
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/// call to source_map's `is_internal` check.
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/// The expanded code uses the unstable `#[prelude_import]` attribute.
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fn ignored_span(sp: Span) -> Span {
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let mark = Mark::fresh(Mark::root());
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mark.set_expn_info(ExpnInfo {
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call_site: DUMMY_SP,
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def_site: None,
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format: MacroAttribute(Symbol::intern("std_inject")),
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allow_internal_unstable: Some(vec![
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Symbol::intern("prelude_import"),
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].into()),
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allow_internal_unsafe: false,
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local_inner_macros: false,
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edition: hygiene::default_edition(),
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});
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sp.with_ctxt(SyntaxContext::empty().apply_mark(mark))
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}
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pub fn injected_crate_name() -> Option<&'static str> {
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INJECTED_CRATE_NAME.with(|name| name.get())
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}
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thread_local! {
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static INJECTED_CRATE_NAME: Cell<Option<&'static str>> = Cell::new(None);
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}
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pub fn maybe_inject_crates_ref(
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mut krate: ast::Crate,
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alt_std_name: Option<&str>,
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edition: Edition,
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) -> ast::Crate {
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let rust_2018 = edition >= Edition::Edition2018;
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// the first name in this list is the crate name of the crate with the prelude
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let names: &[&str] = if attr::contains_name(&krate.attrs, "no_core") {
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return krate;
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} else if attr::contains_name(&krate.attrs, "no_std") {
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if attr::contains_name(&krate.attrs, "compiler_builtins") {
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&["core"]
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} else {
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&["core", "compiler_builtins"]
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}
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} else {
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&["std"]
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};
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// .rev() to preserve ordering above in combination with insert(0, ...)
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let alt_std_name = alt_std_name.map(Symbol::intern);
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for orig_name in names.iter().rev() {
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let orig_name = Symbol::intern(orig_name);
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let mut rename = orig_name;
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// HACK(eddyb) gensym the injected crates on the Rust 2018 edition,
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// so they don't accidentally interfere with the new import paths.
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if rust_2018 {
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rename = orig_name.gensymed();
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}
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let orig_name = if rename != orig_name {
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Some(orig_name)
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} else {
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None
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};
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krate.module.items.insert(0, P(ast::Item {
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attrs: vec![attr::mk_attr_outer(DUMMY_SP,
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attr::mk_attr_id(),
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attr::mk_word_item(ast::Ident::from_str("macro_use")))],
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vis: dummy_spanned(ast::VisibilityKind::Inherited),
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node: ast::ItemKind::ExternCrate(alt_std_name.or(orig_name)),
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ident: ast::Ident::with_empty_ctxt(rename),
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id: ast::DUMMY_NODE_ID,
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span: DUMMY_SP,
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tokens: None,
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}));
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}
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// the crates have been injected, the assumption is that the first one is the one with
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// the prelude.
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let name = names[0];
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INJECTED_CRATE_NAME.with(|opt_name| opt_name.set(Some(name)));
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let span = ignored_span(DUMMY_SP);
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krate.module.items.insert(0, P(ast::Item {
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attrs: vec![ast::Attribute {
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style: ast::AttrStyle::Outer,
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path: ast::Path::from_ident(ast::Ident::new(Symbol::intern("prelude_import"), span)),
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tokens: TokenStream::empty(),
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id: attr::mk_attr_id(),
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is_sugared_doc: false,
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span,
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}],
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vis: respan(span.shrink_to_lo(), ast::VisibilityKind::Inherited),
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node: ast::ItemKind::Use(P(ast::UseTree {
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prefix: ast::Path {
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segments: iter::once(keywords::PathRoot.ident())
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.chain(
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[name, "prelude", "v1"].iter().cloned()
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.map(ast::Ident::from_str)
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).map(ast::PathSegment::from_ident).collect(),
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span,
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},
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kind: ast::UseTreeKind::Glob,
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span,
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})),
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id: ast::DUMMY_NODE_ID,
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ident: keywords::Invalid.ident(),
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span,
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tokens: None,
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}));
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krate
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}
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