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