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Revert "Partially outline code inside the panic! macro".

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Without any tests/benchmarks that show some improvement, it's hard to
know whether the change had any positive effect at all. (And if it did,
whether that effect is still achieved today.)
This commit is contained in:
Mara Bos 2025-08-12 12:52:39 +02:00
parent a1531335fe
commit 08acba3071
9 changed files with 8 additions and 73 deletions
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6
compiler/rustc_const_eval/src/check_consts/check.rs
View file

@ -827,7 +827,7 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
// At this point, we are calling a function, `callee`, whose `DefId` is known...
// `begin_panic` and `#[rustc_const_panic_str]` functions accept generic
// `begin_panic` and `panic_display` functions accept generic
// types other than str. Check to enforce that only str can be used in
// const-eval.
@ -841,8 +841,8 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
return;
}
// const-eval of `#[rustc_const_panic_str]` functions assumes the argument is `&&str`
if tcx.has_attr(callee, sym::rustc_const_panic_str) {
// const-eval of `panic_display` assumes the argument is `&&str`
if tcx.is_lang_item(callee, LangItem::PanicDisplay) {
match args[0].node.ty(&self.ccx.body.local_decls, tcx).kind() {
ty::Ref(_, ty, _) if matches!(ty.kind(), ty::Ref(_, ty, _) if ty.is_str()) =>
{}

2
compiler/rustc_const_eval/src/const_eval/machine.rs
View file

@ -237,7 +237,7 @@ impl<'tcx> CompileTimeInterpCx<'tcx> {
) -> InterpResult<'tcx, Option<ty::Instance<'tcx>>> {
let def_id = instance.def_id();
if self.tcx.has_attr(def_id, sym::rustc_const_panic_str)
if self.tcx.is_lang_item(def_id, LangItem::PanicDisplay)
|| self.tcx.is_lang_item(def_id, LangItem::BeginPanic)
{
let args = self.copy_fn_args(args);

4
compiler/rustc_feature/src/builtin_attrs.rs
View file

@ -929,10 +929,6 @@ pub static BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
rustc_do_not_const_check, Normal, template!(Word), WarnFollowing,
EncodeCrossCrate::Yes, "`#[rustc_do_not_const_check]` skips const-check for this function's body",
),
rustc_attr!(
rustc_const_panic_str, Normal, template!(Word), WarnFollowing,
EncodeCrossCrate::Yes, "`#[rustc_const_panic_str]` ensures the argument to this function is &&str during const-check",
),
rustc_attr!(
rustc_const_stable_indirect, Normal,
template!(Word),

1
compiler/rustc_hir/src/lang_items.rs
View file

@ -286,6 +286,7 @@ language_item_table! {
Panic, sym::panic, panic_fn, Target::Fn, GenericRequirement::Exact(0);
PanicNounwind, sym::panic_nounwind, panic_nounwind, Target::Fn, GenericRequirement::Exact(0);
PanicFmt, sym::panic_fmt, panic_fmt, Target::Fn, GenericRequirement::None;
PanicDisplay, sym::panic_display, panic_display, Target::Fn, GenericRequirement::None;
ConstPanicFmt, sym::const_panic_fmt, const_panic_fmt, Target::Fn, GenericRequirement::None;
PanicBoundsCheck, sym::panic_bounds_check, panic_bounds_check_fn, Target::Fn, GenericRequirement::Exact(0);
PanicMisalignedPointerDereference, sym::panic_misaligned_pointer_dereference, panic_misaligned_pointer_dereference_fn, Target::Fn, GenericRequirement::Exact(0);

2
compiler/rustc_span/src/symbol.rs
View file

@ -1583,6 +1583,7 @@ symbols! {
panic_const_shl_overflow,
panic_const_shr_overflow,
panic_const_sub_overflow,
panic_display,
panic_fmt,
panic_handler,
panic_impl,
@ -1828,7 +1829,6 @@ symbols! {
rustc_coherence_is_core,
rustc_coinductive,
rustc_confusables,
rustc_const_panic_str,
rustc_const_stable,
rustc_const_stable_indirect,
rustc_const_unstable,

45
library/core/src/panic.rs
View file

@ -48,7 +48,6 @@ pub macro panic_2015 {
#[allow_internal_unstable(panic_internals, const_format_args)]
#[rustc_diagnostic_item = "core_panic_2021_macro"]
#[rustc_macro_transparency = "semitransparent"]
#[cfg(feature = "panic_immediate_abort")]
pub macro panic_2021 {
() => (
$crate::panicking::panic("explicit panic")
@ -64,50 +63,6 @@ pub macro panic_2021 {
}),
}
#[doc(hidden)]
#[unstable(feature = "edition_panic", issue = "none", reason = "use panic!() instead")]
#[allow_internal_unstable(
panic_internals,
core_intrinsics,
const_dispatch,
const_eval_select,
const_format_args,
rustc_attrs
)]
#[rustc_diagnostic_item = "core_panic_2021_macro"]
#[rustc_macro_transparency = "semitransparent"]
#[cfg(not(feature = "panic_immediate_abort"))]
pub macro panic_2021 {
() => ({
// Create a function so that the argument for `track_caller`
// can be moved inside if possible.
#[cold]
#[track_caller]
#[inline(never)]
const fn panic_cold_explicit() -> ! {
$crate::panicking::panic_explicit()
}
panic_cold_explicit();
}),
// Special-case the single-argument case for const_panic.
("{}", $arg:expr $(,)?) => ({
#[cold]
#[track_caller]
#[inline(never)]
#[rustc_const_panic_str] // enforce a &&str argument in const-check and hook this by const-eval
#[rustc_do_not_const_check] // hooked by const-eval
const fn panic_cold_display<T: $crate::fmt::Display>(arg: &T) -> ! {
$crate::panicking::panic_display(arg)
}
panic_cold_display(&$arg);
}),
($($t:tt)+) => ({
// Semicolon to prevent temporaries inside the formatting machinery from
// being considered alive in the caller after the panic_fmt call.
$crate::panicking::panic_fmt($crate::const_format_args!($($t)+));
}),
}
#[doc(hidden)]
#[unstable(feature = "edition_panic", issue = "none", reason = "use unreachable!() instead")]
#[allow_internal_unstable(panic_internals)]

11
library/core/src/panicking.rs
View file

@ -233,14 +233,6 @@ pub fn panic_nounwind_nobacktrace(expr: &'static str) -> ! {
panic_nounwind_fmt(fmt::Arguments::new_const(&[expr]), /* force_no_backtrace */ true);
}
#[track_caller]
#[cfg_attr(not(feature = "panic_immediate_abort"), inline(never), cold)]
#[cfg_attr(feature = "panic_immediate_abort", inline)]
#[rustc_const_stable_indirect] // must follow stable const rules since it is exposed to stable
pub const fn panic_explicit() -> ! {
panic_display(&"explicit panic");
}
#[inline]
#[track_caller]
#[rustc_diagnostic_item = "unreachable_display"] // needed for `non-fmt-panics` lint
@ -260,9 +252,8 @@ pub const fn panic_str_2015(expr: &str) -> ! {
#[inline]
#[track_caller]
#[lang = "panic_display"] // needed for const-evaluated panics
#[rustc_do_not_const_check] // hooked by const-eval
// enforce a &&str argument in const-check and hook this by const-eval
#[rustc_const_panic_str]
#[rustc_const_stable_indirect] // must follow stable const rules since it is exposed to stable
pub const fn panic_display<T: fmt::Display>(x: &T) -> ! {
panic_fmt(format_args!("{}", *x));

7
src/tools/clippy/clippy_utils/src/macros.rs
View file

@ -250,18 +250,13 @@ impl<'a> PanicExpn<'a> {
};
let name = path.segments.last().unwrap().ident.name;
// This has no argument
if name == sym::panic_cold_explicit {
return Some(Self::Empty);
}
let [arg, rest @ ..] = args else {
return None;
};
let result = match name {
sym::panic if arg.span.eq_ctxt(expr.span) => Self::Empty,
sym::panic | sym::panic_str => Self::Str(arg),
sym::panic_display | sym::panic_cold_display => {
sym::panic_display => {
let ExprKind::AddrOf(_, _, e) = &arg.kind else {
return None;
};

3
src/tools/clippy/clippy_utils/src/sym.rs
View file

@ -241,9 +241,6 @@ generate! {
or_insert,
or_insert_with,
outer_expn,
panic_cold_display,
panic_cold_explicit,
panic_display,
panic_str,
parse,
partition,