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hygiene: Introduce a helper method for creating new expansions

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Creating a fresh expansion and immediately generating a span from it is the most common scenario.

Also avoid allocating `allow_internal_unstable` lists for derive markers repeatedly.
And rename `ExpnInfo::with_unstable` to `ExpnInfo::allow_unstable`, seems to be a better fitting name.
This commit is contained in:
Vadim Petrochenkov
2019-07-06 21:02:45 +03:00
parent d1949b1ab0
commit 99c7432896
12 changed files with 80 additions and 117 deletions
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22
src/libsyntax/std_inject.rs
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@@ -1,7 +1,7 @@
use crate::ast;
use crate::attr;
use crate::edition::Edition;
use crate::ext::hygiene::{Mark, SyntaxContext, MacroKind};
use crate::ext::hygiene::{Mark, MacroKind};
use crate::symbol::{Ident, Symbol, kw, sym};
use crate::source_map::{ExpnInfo, ExpnKind, dummy_spanned, respan};
use crate::ptr::P;
@@ -9,19 +9,7 @@ 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(
ExpnKind::Macro(MacroKind::Attr, Symbol::intern("std_inject")), sp, edition,
&[sym::prelude_import],
));
sp.with_ctxt(SyntaxContext::empty().apply_mark(mark))
}
use syntax_pos::DUMMY_SP;
pub fn injected_crate_name() -> Option<&'static str> {
INJECTED_CRATE_NAME.with(|name| name.get())
@@ -87,7 +75,11 @@ pub fn maybe_inject_crates_ref(
INJECTED_CRATE_NAME.with(|opt_name| opt_name.set(Some(name)));
let span = ignored_span(DUMMY_SP, edition);
let span = DUMMY_SP.fresh_expansion(Mark::root(), ExpnInfo::allow_unstable(
ExpnKind::Macro(MacroKind::Attr, sym::std_inject), DUMMY_SP, edition,
[sym::prelude_import][..].into(),
));
krate.module.items.insert(0, P(ast::Item {
attrs: vec![ast::Attribute {
style: ast::AttrStyle::Outer,