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use rustc_ast::ptr::P;
use rustc_ast::tokenstream::{DelimSpan, TokenStream};
use rustc_ast::*;
use rustc_expand::base::*;
use rustc_span::edition::Edition;
use rustc_span::symbol::sym;
use rustc_span::Span;
// This expands to either
// - `$crate::panic::panic_2015!(...)` or
// - `$crate::panic::panic_2021!(...)`
// depending on the edition.
//
// This is used for both std::panic!() and core::panic!().
//
// `$crate` will refer to either the `std` or `core` crate depending on which
// one we're expanding from.
pub fn expand_panic<'cx>(
cx: &'cx mut ExtCtxt<'_>,
sp: Span,
tts: TokenStream,
) -> Box<dyn MacResult + 'cx> {
let mac = if use_panic_2021(sp) { sym::panic_2021 } else { sym::panic_2015 };
expand(mac, cx, sp, tts)
}
// This expands to either
// - `$crate::panic::unreachable_2015!(...)` or
// - `$crate::panic::unreachable_2021!(...)`
// depending on the edition.
pub fn expand_unreachable<'cx>(
cx: &'cx mut ExtCtxt<'_>,
sp: Span,
tts: TokenStream,
) -> Box<dyn MacResult + 'cx> {
let mac = if use_panic_2021(sp) { sym::unreachable_2021 } else { sym::unreachable_2015 };
expand(mac, cx, sp, tts)
}
fn expand<'cx>(
mac: rustc_span::Symbol,
cx: &'cx mut ExtCtxt<'_>,
sp: Span,
tts: TokenStream,
) -> Box<dyn MacResult + 'cx> {
let sp = cx.with_call_site_ctxt(sp);
MacEager::expr(
cx.expr(
sp,
ExprKind::MacCall(MacCall {
path: Path {
span: sp,
segments: cx
.std_path(&[sym::panic, mac])
.into_iter()
.map(|ident| PathSegment::from_ident(ident))
.collect(),
tokens: None,
},
args: P(MacArgs::Delimited(
DelimSpan::from_single(sp),
MacDelimiter::Parenthesis,
tts,
)),
prior_type_ascription: None,
}),
),
)
}
pub fn use_panic_2021(mut span: Span) -> bool {
// To determine the edition, we check the first span up the expansion
// stack that does not have #[allow_internal_unstable(edition_panic)].
// (To avoid using the edition of e.g. the assert!() or debug_assert!() definition.)
loop {
let expn = span.ctxt().outer_expn_data();
if let Some(features) = expn.allow_internal_unstable {
if features.iter().any(|&f| f == sym::edition_panic) {
span = expn.call_site;
continue;
}
}
break expn.edition >= Edition::Edition2021;
}
}
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