From ee8ca0a89ff8bff74c98ac0920cbfcb366354286 Mon Sep 17 00:00:00 2001
From: Jonathan Brouwer <jonathantbrouwer@gmail.com>
Date: Fri, 13 Feb 2026 12:43:02 +0000
Subject: [PATCH] Port `#[panic_handler]` to the new attribute parsers

---
 .../rustc_attr_parsing/src/attributes/rustc_internal.rs  | 9 +++++++++
 compiler/rustc_attr_parsing/src/context.rs               | 1 +
 compiler/rustc_passes/src/lang_items.rs                  | 2 +-
 3 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/compiler/rustc_attr_parsing/src/attributes/rustc_internal.rs b/compiler/rustc_attr_parsing/src/attributes/rustc_internal.rs
index 7dbf38419a4b..e7b639c9af18 100644
--- a/compiler/rustc_attr_parsing/src/attributes/rustc_internal.rs
+++ b/compiler/rustc_attr_parsing/src/attributes/rustc_internal.rs
@@ -668,6 +668,15 @@ impl<S: Stage> NoArgsAttributeParser<S> for RustcHasIncoherentInherentImplsParse
     const CREATE: fn(Span) -> AttributeKind = |_| AttributeKind::RustcHasIncoherentInherentImpls;
 }
 
+pub(crate) struct PanicHandlerParser;
+
+impl<S: Stage> NoArgsAttributeParser<S> for PanicHandlerParser {
+    const PATH: &[Symbol] = &[sym::panic_handler];
+    const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(ALL_TARGETS); // Targets are checked per lang item in `rustc_passes`
+    const CREATE: fn(Span) -> AttributeKind = |span| AttributeKind::Lang(LangItem::PanicImpl, span);
+}
+
 pub(crate) struct RustcHiddenTypeOfOpaquesParser;
 
 impl<S: Stage> NoArgsAttributeParser<S> for RustcHiddenTypeOfOpaquesParser {
diff --git a/compiler/rustc_attr_parsing/src/context.rs b/compiler/rustc_attr_parsing/src/context.rs
index b61da848967a..93a2b819c51f 100644
--- a/compiler/rustc_attr_parsing/src/context.rs
+++ b/compiler/rustc_attr_parsing/src/context.rs
@@ -254,6 +254,7 @@ attribute_parsers!(
         Single<WithoutArgs<NoMangleParser>>,
         Single<WithoutArgs<NoStdParser>>,
         Single<WithoutArgs<NonExhaustiveParser>>,
+        Single<WithoutArgs<PanicHandlerParser>>,
         Single<WithoutArgs<PanicRuntimeParser>>,
         Single<WithoutArgs<ParenSugarParser>>,
         Single<WithoutArgs<PassByValueParser>>,
diff --git a/compiler/rustc_passes/src/lang_items.rs b/compiler/rustc_passes/src/lang_items.rs
index ba71630d2681..25aea8e9f82a 100644
--- a/compiler/rustc_passes/src/lang_items.rs
+++ b/compiler/rustc_passes/src/lang_items.rs
@@ -8,7 +8,7 @@
 //! * Functions called by the compiler itself.
 
 use rustc_ast as ast;
-use rustc_ast::fmvisit;
+use rustc_ast::visit;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_hir::lang_items::GenericRequirement;