From e99e226748d3438d40a11ff556820375a762c8e1 Mon Sep 17 00:00:00 2001
From: Josh Triplett <josh@joshtriplett.org>
Date: Sun, 21 Sep 2025 23:20:20 +0800
Subject: Switch `dummy_bang` from `LegacyBang` to `Bang`

---
 compiler/rustc_expand/src/base.rs   | 23 ++++++++++-------------
 compiler/rustc_expand/src/expand.rs |  2 +-
 2 files changed, 11 insertions(+), 14 deletions(-)

diff --git a/compiler/rustc_expand/src/base.rs b/compiler/rustc_expand/src/base.rs
index 88f88f30a8c..7db1be24f24 100644
--- a/compiler/rustc_expand/src/base.rs
+++ b/compiler/rustc_expand/src/base.rs
@@ -324,16 +324,16 @@ pub trait BangProcMacro {
 
 impl<F> BangProcMacro for F
 where
-    F: Fn(TokenStream) -> TokenStream,
+    F: Fn(&mut ExtCtxt<'_>, Span, TokenStream) -> Result<TokenStream, ErrorGuaranteed>,
 {
     fn expand<'cx>(
         &self,
-        _ecx: &'cx mut ExtCtxt<'_>,
-        _span: Span,
+        ecx: &'cx mut ExtCtxt<'_>,
+        span: Span,
         ts: TokenStream,
     ) -> Result<TokenStream, ErrorGuaranteed> {
         // FIXME setup implicit context in TLS before calling self.
-        Ok(self(ts))
+        self(ecx, span, ts)
     }
 }
 
@@ -999,17 +999,14 @@ impl SyntaxExtension {
 
     /// A dummy bang macro `foo!()`.
     pub fn dummy_bang(edition: Edition) -> SyntaxExtension {
-        fn expander<'cx>(
-            cx: &'cx mut ExtCtxt<'_>,
+        fn expand(
+            ecx: &mut ExtCtxt<'_>,
             span: Span,
-            _: TokenStream,
-        ) -> MacroExpanderResult<'cx> {
-            ExpandResult::Ready(DummyResult::any(
-                span,
-                cx.dcx().span_delayed_bug(span, "expanded a dummy bang macro"),
-            ))
+            _ts: TokenStream,
+        ) -> Result<TokenStream, ErrorGuaranteed> {
+            Err(ecx.dcx().span_delayed_bug(span, "expanded a dummy bang macro"))
         }
-        SyntaxExtension::default(SyntaxExtensionKind::LegacyBang(Arc::new(expander)), edition)
+        SyntaxExtension::default(SyntaxExtensionKind::Bang(Arc::new(expand)), edition)
     }
 
     /// A dummy derive macro `#[derive(Foo)]`.
diff --git a/compiler/rustc_expand/src/expand.rs b/compiler/rustc_expand/src/expand.rs
index 4c0e0bbfe26..172bc3d1d9f 100644
--- a/compiler/rustc_expand/src/expand.rs
+++ b/compiler/rustc_expand/src/expand.rs
@@ -971,7 +971,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                             });
                         }
                     },
-                    SyntaxExtensionKind::LegacyBang(..) => {
+                    SyntaxExtensionKind::Bang(..) => {
                         let msg = "expanded a dummy glob delegation";
                         let guar = self.cx.dcx().span_delayed_bug(span, msg);
                         return ExpandResult::Ready(fragment_kind.dummy(span, guar));
-- 
cgit 1.4.1-3-g733a5


From a1646bf90c12c168a898361d2ef34e73311eccde Mon Sep 17 00:00:00 2001
From: Josh Triplett <josh@joshtriplett.org>
Date: Sun, 21 Sep 2025 23:28:10 +0800
Subject: mbe: Switch dummy extension used for errors from `LegacyBang` to
 `Bang`

---
 compiler/rustc_expand/src/mbe/macro_rules.rs | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/compiler/rustc_expand/src/mbe/macro_rules.rs b/compiler/rustc_expand/src/mbe/macro_rules.rs
index 1d147a0385c..9ed4c56efb3 100644
--- a/compiler/rustc_expand/src/mbe/macro_rules.rs
+++ b/compiler/rustc_expand/src/mbe/macro_rules.rs
@@ -33,8 +33,8 @@ use super::diagnostics::{FailedMacro, failed_to_match_macro};
 use super::macro_parser::{NamedMatches, NamedParseResult};
 use super::{SequenceRepetition, diagnostics};
 use crate::base::{
-    AttrProcMacro, DummyResult, ExpandResult, ExtCtxt, MacResult, MacroExpanderResult,
-    SyntaxExtension, SyntaxExtensionKind, TTMacroExpander,
+    AttrProcMacro, BangProcMacro, DummyResult, ExpandResult, ExtCtxt, MacResult,
+    MacroExpanderResult, SyntaxExtension, SyntaxExtensionKind, TTMacroExpander,
 };
 use crate::errors;
 use crate::expand::{AstFragment, AstFragmentKind, ensure_complete_parse, parse_ast_fragment};
@@ -267,16 +267,16 @@ impl AttrProcMacro for MacroRulesMacroExpander {
     }
 }
 
-struct DummyExpander(ErrorGuaranteed);
+struct DummyBang(ErrorGuaranteed);
 
-impl TTMacroExpander for DummyExpander {
+impl BangProcMacro for DummyBang {
     fn expand<'cx>(
         &self,
         _: &'cx mut ExtCtxt<'_>,
-        span: Span,
+        _: Span,
         _: TokenStream,
-    ) -> ExpandResult<Box<dyn MacResult + 'cx>, ()> {
-        ExpandResult::Ready(DummyResult::any(span, self.0))
+    ) -> Result<TokenStream, ErrorGuaranteed> {
+        Err(self.0)
     }
 }
 
@@ -664,7 +664,7 @@ pub fn compile_declarative_macro(
         SyntaxExtension::new(sess, kind, span, Vec::new(), edition, ident.name, attrs, is_local)
     };
     let dummy_syn_ext =
-        |guar| (mk_syn_ext(SyntaxExtensionKind::LegacyBang(Arc::new(DummyExpander(guar)))), 0);
+        |guar| (mk_syn_ext(SyntaxExtensionKind::Bang(Arc::new(DummyBang(guar)))), 0);
 
     let macro_rules = macro_def.macro_rules;
     let exp_sep = if macro_rules { exp!(Semi) } else { exp!(Comma) };
-- 
cgit 1.4.1-3-g733a5