fix: Fix macro transcriber emitting incorrect lifetime tokens

4 files changed, 73 insertions, 6 deletions

diff --git a/crates/hir-def/src/macro_expansion_tests/mbe/regression.rs b/crates/hir-def/src/macro_expansion_tests/mbe/regression.rs
index 6717ee1aa5f..4aad53c3bd7 100644
--- a/crates/hir-def/src/macro_expansion_tests/mbe/regression.rs
+++ b/crates/hir-def/src/macro_expansion_tests/mbe/regression.rs
@@ -1090,3 +1090,57 @@ fn main() {
 "#]],
     );
 }
+
+#[test]
+fn regression_16529() {
+    check(
+        r#"
+mod any {
+    #[macro_export]
+    macro_rules! nameable {
+        {
+            struct $name:ident[$a:lifetime]
+        } => {
+            $crate::any::nameable! {
+                struct $name[$a]
+                a
+            }
+        };
+        {
+            struct $name:ident[$a:lifetime]
+            a
+        } => {};
+    }
+    pub use nameable;
+
+    nameable! {
+        Name['a]
+    }
+}
+"#,
+        expect![[r#"
+mod any {
+    #[macro_export]
+    macro_rules! nameable {
+        {
+            struct $name:ident[$a:lifetime]
+        } => {
+            $crate::any::nameable! {
+                struct $name[$a]
+                a
+            }
+        };
+        {
+            struct $name:ident[$a:lifetime]
+            a
+        } => {};
+    }
+    pub use nameable;
+
+    /* error: unexpected token in input */$crate::any::nameable! {
+        struct $name[$a]a
+    }
+}
+"#]],
+    );
+}
diff --git a/crates/mbe/src/expander/transcriber.rs b/crates/mbe/src/expander/transcriber.rs
index 9291f799cca..6d3055da286 100644
--- a/crates/mbe/src/expander/transcriber.rs
+++ b/crates/mbe/src/expander/transcriber.rs
@@ -101,10 +101,20 @@ impl<S: Span> Bindings<S> {
                         })))
                     }
                     MetaVarKind::Lifetime => {
-                        Fragment::Tokens(tt::TokenTree::Leaf(tt::Leaf::Ident(tt::Ident {
-                            text: SmolStr::new_static("'missing"),
-                            span,
-                        })))
+                        Fragment::Tokens(tt::TokenTree::Subtree(tt::Subtree {
+                            delimiter: tt::Delimiter::invisible_spanned(span),
+                            token_trees: Box::new([
+                                tt::TokenTree::Leaf(tt::Leaf::Punct(tt::Punct {
+                                    char: '\'',
+                                    span,
+                                    spacing: tt::Spacing::Joint,
+                                })),
+                                tt::TokenTree::Leaf(tt::Leaf::Ident(tt::Ident {
+                                    text: SmolStr::new_static("missing"),
+                                    span,
+                                })),
+                            ]),
+                        }))
                     }
                     MetaVarKind::Literal => {
                         Fragment::Tokens(tt::TokenTree::Leaf(tt::Leaf::Ident(tt::Ident {
diff --git a/crates/mbe/src/syntax_bridge.rs b/crates/mbe/src/syntax_bridge.rs
index bfc5d197f68..3c270e30a9b 100644
--- a/crates/mbe/src/syntax_bridge.rs
+++ b/crates/mbe/src/syntax_bridge.rs
@@ -700,10 +700,12 @@ impl<S> SynToken<S> {
 }
 
 impl<SpanMap, S: std::fmt::Debug> SrcToken<Converter<SpanMap, S>, S> for SynToken<S> {
-    fn kind(&self, ctx: &Converter<SpanMap, S>) -> SyntaxKind {
+    fn kind(&self, _ctx: &Converter<SpanMap, S>) -> SyntaxKind {
         match self {
             SynToken::Ordinary(token) => token.kind(),
-            SynToken::Punct { .. } => SyntaxKind::from_char(self.to_char(ctx).unwrap()).unwrap(),
+            SynToken::Punct { token, offset: i } => {
+                SyntaxKind::from_char(token.text().chars().nth(*i).unwrap()).unwrap()
+            }
             SynToken::Leaf(_) => {
                 never!();
                 SyntaxKind::ERROR
diff --git a/crates/tt/src/lib.rs b/crates/tt/src/lib.rs
index 9004bff53a8..eec88f80688 100644
--- a/crates/tt/src/lib.rs
+++ b/crates/tt/src/lib.rs
@@ -152,6 +152,7 @@ pub struct Punct<S> {
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub enum Spacing {
     Alone,
+    /// Whether the following token is joint to the current one.
     Joint,
 }