Merge #7211

7211: Fixed expr meta var after path colons in mbe r=matklad a=edwin0cheng

Fixes #7207

Added `L_DOLLAR` in `ITEM_RECOVERY_SET` , but I don't know whether it is a good idea.

r? @matklad 

Co-authored-by: Edwin Cheng <edwin0cheng@gmail.com>

crates/mbe/src/tests.rs

@@ -1,7 +1,11 @@
 use std::fmt::Write;
 
 use ::parser::FragmentKind;
-use syntax::{ast, AstNode, NodeOrToken, SyntaxKind::IDENT, SyntaxNode, WalkEvent, T};
+use syntax::{
+    ast, AstNode, NodeOrToken,
+    SyntaxKind::{ERROR, IDENT},
+    SyntaxNode, WalkEvent, T,
+};
 use test_utils::assert_eq_text;
 
 use super::*;
@@ -1194,6 +1198,23 @@ fn $b() -> u8 {$c}
     );
 }
 
+#[test]
+fn test_expr_after_path_colons() {
+    assert!(parse_macro(
+        r#"
+macro_rules! m {
+    ($k:expr) => {
+            f(K::$k);
+       }
+}
+"#,
+    )
+    .expand_statements(r#"m!(C("0"))"#)
+    .descendants()
+    .find(|token| token.kind() == ERROR)
+    .is_some());
+}
+
 // The following tests are based on real world situations
 #[test]
 fn test_vec() {

crates/parser/src/parser.rs

@@ -7,7 +7,7 @@
 use crate::{
     event::Event,
     ParseError,
-    SyntaxKind::{self, EOF, ERROR, TOMBSTONE},
+    SyntaxKind::{self, EOF, ERROR, L_DOLLAR, R_DOLLAR, TOMBSTONE},
     TokenSet, TokenSource, T,
 };
 
@@ -215,13 +215,23 @@ pub(crate) fn expect(&mut self, kind: SyntaxKind) -> bool {
 
     /// Create an error node and consume the next token.
     pub(crate) fn err_and_bump(&mut self, message: &str) {
-        self.err_recover(message, TokenSet::EMPTY);
+        match self.current() {
+            L_DOLLAR | R_DOLLAR => {
+                let m = self.start();
+                self.error(message);
+                self.bump_any();
+                m.complete(self, ERROR);
+            }
+            _ => {
+                self.err_recover(message, TokenSet::EMPTY);
+            }
+        }
     }
 
     /// Create an error node and consume the next token.
     pub(crate) fn err_recover(&mut self, message: &str, recovery: TokenSet) {
         match self.current() {
-            T!['{'] | T!['}'] => {
+            T!['{'] | T!['}'] | L_DOLLAR | R_DOLLAR => {
                 self.error(message);
                 return;
             }