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// `#![no_std]`: these arrive with the standard prelude and name no path, so a `std::`
// search cannot see them - and a `#[derive]` can use them without the name appearing
// in this file at all, which is why they are not trimmed by inspection.
use alloc::borrow::ToOwned;
use alloc::boxed::Box;
use alloc::format;
use alloc::string::{String, ToString};
use alloc::vec;
use alloc::vec::Vec;
use crate::rustc_ast::token::Delimiter;
use crate::rustc_ast::tokenstream::{DelimSpan, TokenStream};
use crate::rustc_ast::*;
use crate::rustc_expand::base::*;
use crate::rustc_span::edition::Edition;
use crate::rustc_span::{Span, sym};
/// This expands to either
/// - `$crate::rustc_builtin_macros::panic::panic_2015!(...)` or
/// - `$crate::rustc_builtin_macros::panic::panic_2021!(...)`
/// depending on the edition.
///
/// This is used for both core::panic!() and core::panic!().
///
/// `$crate` will refer to either the `std` or `core` crate depending on which
/// one we're expanding from.
pub(crate) fn expand_panic<'cx>(
cx: &'cx mut ExtCtxt<'_>,
sp: Span,
tts: TokenStream,
) -> MacroExpanderResult<'cx> {
let mac = if use_panic_2021(sp) { sym::panic_2021 } else { sym::panic_2015 };
expand(mac, cx, sp, tts)
}
/// This expands to either
/// - `$crate::rustc_builtin_macros::panic::unreachable_2015!(...)` or
/// - `$crate::rustc_builtin_macros::panic::unreachable_2021!(...)`
/// depending on the edition.
pub(crate) fn expand_unreachable<'cx>(
cx: &'cx mut ExtCtxt<'_>,
sp: Span,
tts: TokenStream,
) -> MacroExpanderResult<'cx> {
let mac = if use_panic_2021(sp) { sym::unreachable_2021 } else { sym::unreachable_2015 };
expand(mac, cx, sp, tts)
}
fn expand<'cx>(
mac: crate::rustc_span::Symbol,
cx: &'cx ExtCtxt<'_>,
sp: Span,
tts: TokenStream,
) -> MacroExpanderResult<'cx> {
let sp = cx.with_call_site_ctxt(sp);
ExpandResult::Ready(MacEager::expr(
cx.expr(
sp,
ExprKind::MacCall(Box::new(MacCall {
path: Path {
span: sp,
segments: cx
.std_path(&[sym::panic, mac])
.into_iter()
.map(PathSegment::from_ident)
.collect(),
},
args: Box::new(DelimArgs {
dspan: DelimSpan::from_single(sp),
delim: Delimiter::Parenthesis,
tokens: tts,
}),
})),
),
))
}
pub(crate) 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
&& features.contains(&sym::edition_panic)
{
span = expn.call_site;
continue;
}
break expn.edition >= Edition::Edition2021;
}
}