Fix parsing of labeled loop followed by paren in stmt or match arm po…

…sition
dtolnay · Dec 11, 2023 · a78859f · a78859f
1 parent 1a77631
commit a78859f
Show file tree

Hide file tree

Showing 2 changed files with 38 additions and 29 deletions.
diff --git a/src/expr.rs b/src/expr.rs
@@ -1663,31 +1663,36 @@ pub(crate) mod parsing {
         } else if input.peek(Token![_]) {
             input.parse().map(Expr::Infer)
         } else if input.peek(Lifetime) {
-            let the_label: Label = input.parse()?;
-            let mut expr = if input.peek(Token![while]) {
-                Expr::While(input.parse()?)
-            } else if input.peek(Token![for]) {
-                Expr::ForLoop(input.parse()?)
-            } else if input.peek(Token![loop]) {
-                Expr::Loop(input.parse()?)
-            } else if input.peek(token::Brace) {
-                Expr::Block(input.parse()?)
-            } else {
-                return Err(input.error("expected loop or block expression"));
-            };
-            match &mut expr {
-                Expr::While(ExprWhile { label, .. })
-                | Expr::ForLoop(ExprForLoop { label, .. })
-                | Expr::Loop(ExprLoop { label, .. })
-                | Expr::Block(ExprBlock { label, .. }) => *label = Some(the_label),
-                _ => unreachable!(),
-            }
-            Ok(expr)
+            atom_labeled(input)
         } else {
             Err(input.error("expected an expression"))
         }
     }
 
+    #[cfg(feature = "full")]
+    fn atom_labeled(input: ParseStream) -> Result<Expr> {
+        let the_label: Label = input.parse()?;
+        let mut expr = if input.peek(Token![while]) {
+            Expr::While(input.parse()?)
+        } else if input.peek(Token![for]) {
+            Expr::ForLoop(input.parse()?)
+        } else if input.peek(Token![loop]) {
+            Expr::Loop(input.parse()?)
+        } else if input.peek(token::Brace) {
+            Expr::Block(input.parse()?)
+        } else {
+            return Err(input.error("expected loop or block expression"));
+        };
+        match &mut expr {
+            Expr::While(ExprWhile { label, .. })
+            | Expr::ForLoop(ExprForLoop { label, .. })
+            | Expr::Loop(ExprLoop { label, .. })
+            | Expr::Block(ExprBlock { label, .. }) => *label = Some(the_label),
+            _ => unreachable!(),
+        }
+        Ok(expr)
+    }
+
     #[cfg(not(feature = "full"))]
     fn atom_expr(input: ParseStream) -> Result<Expr> {
         if input.peek(token::Group)
@@ -1935,6 +1940,8 @@ pub(crate) mod parsing {
             Expr::Const(input.parse()?)
         } else if input.peek(token::Brace) {
             Expr::Block(input.parse()?)
+        } else if input.peek(Lifetime) {
+            atom_labeled(input)?
         } else {
             let allow_struct = AllowStruct(true);
             let mut expr = unary_expr(input, allow_struct)?;

diff --git a/tests/test_stmt.rs b/tests/test_stmt.rs
@@ -273,18 +273,20 @@ fn test_early_parse_loop() {
     snapshot!(stmts, @r###"
     [
         Stmt::Expr(
-            Expr::Call {
-                func: Expr::Loop {
-                    label: Some(Label {
-                        name: Lifetime {
-                            ident: "a",
-                        },
-                    }),
-                    body: Block,
-                },
+            Expr::Loop {
+                label: Some(Label {
+                    name: Lifetime {
+                        ident: "a",
+                    },
+                }),
+                body: Block,
             },
             None,
         ),
+        Stmt::Expr(
+            Expr::Tuple,
+            None,
+        ),
     ]
     "###);
 }