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use crate::ast;
use crate::attr;
use crate::edition::Edition;
use crate::ext::hygiene::{Mark, SyntaxContext};
use crate::symbol::{Symbol, keywords};
use crate::source_map::{ExpnInfo, MacroAttribute, dummy_spanned, hygiene, 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) -> Span {
let mark = Mark::fresh(Mark::root());
mark.set_expn_info(ExpnInfo {
call_site: DUMMY_SP,
def_site: None,
format: MacroAttribute(Symbol::intern("std_inject")),
allow_internal_unstable: Some(vec![
Symbol::intern("prelude_import"),
].into()),
allow_internal_unsafe: false,
local_inner_macros: false,
edition: hygiene::default_edition(),
});
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! {
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, "no_core") {
return krate;
} else if attr::contains_name(&krate.attrs, "no_std") {
if attr::contains_name(&krate.attrs, "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 in names.iter().rev() {
let orig_name = Symbol::intern(orig_name);
let mut rename = orig_name;
// HACK(eddyb) gensym the injected crates on the Rust 2018 edition,
// so they don't accidentally interfere with the new import paths.
if rust_2018 {
rename = orig_name.gensymed();
}
let orig_name = if rename != orig_name {
Some(orig_name)
} else {
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::from_str("macro_use")))],
vis: dummy_spanned(ast::VisibilityKind::Inherited),
node: ast::ItemKind::ExternCrate(alt_std_name.or(orig_name)),
ident: ast::Ident::with_empty_ctxt(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);
krate.module.items.insert(0, P(ast::Item {
attrs: vec![ast::Attribute {
style: ast::AttrStyle::Outer,
path: ast::Path::from_ident(ast::Ident::new(Symbol::intern("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(keywords::PathRoot.ident())
.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: keywords::Invalid.ident(),
span,
tokens: None,
}));
krate
}
|
