Fix bug in combo-chaining.

CHANGELOG.md

@@ -18,6 +18,7 @@ Bug fixes
 * Fixed crash when parsing multi-segment interpolated string longer than maximum (found via fuzzing).
 * Fixed crash when parsing unterminated comment (found via fuzzing).
 * Fixed crash when parsing deeply-nested right-associated operators such as `**` (found via fuzzing).
+* Fixed crash when parsing combo-chaining expressions such as `(a.b).c` (found via fuzzing).
 
 Deprecated API's
 ----------------

src/parser.rs

@@ -567,7 +567,7 @@ fn optimize_combo_chain(expr: &mut Expr) {
         Expr::Dot(mut x, opt, pos) => match x.lhs.take() {
             #[cfg(not(feature = "no_index"))]
             Expr::Index(x2, opt2, pos2) => (x, opt, pos, x2, opt2, pos2, Expr::Dot, Expr::Index),
-            Expr::Dot(x2, opt2, pos2) => (x, opt, pos, x2, opt2, pos2, Expr::Dot, Expr::Index),
+            Expr::Dot(x2, opt2, pos2) => (x, opt, pos, x2, opt2, pos2, Expr::Dot, Expr::Dot),
             _ => unreachable!("combo chain expected"),
         },
         _ => unreachable!("combo chain expected"),

tests/maps.rs

@@ -24,6 +24,8 @@ fn test_map_indexing() {
     }
 
     assert_eq!(engine.eval::<INT>("let y = #{a: 1, b: 2, c: 3}; y.a = 5; y.a").unwrap(), 5);
+    assert_eq!(engine.eval::<INT>("let y = #{a: #{x:9, y:8, z:7}, b: 2, c: 3}; (y.a).z").unwrap(), 7);
+    assert_eq!(engine.eval::<INT>("let y = #{a: #{x:9, y:8, z:7}, b: 2, c: 3}; (y.a).z = 42; y.a.z").unwrap(), 42);
 
     engine.run("let y = #{a: 1, b: 2, c: 3}; y.z").unwrap();