Fix a desugaring bug

compiler/erg_parser/ast.rs

@@ -1979,7 +1979,13 @@ impl fmt::Display for TypeSpec {
                 }
                 write!(f, "}}")
             }
-            Self::Enum(elems) => write!(f, "{{{elems}}}"),
+            Self::Enum(elems) => {
+                write!(f, "{{")?;
+                for elem in elems.pos_args() {
+                    write!(f, "{}, ", elem.expr)?;
+                }
+                write!(f, "}}")
+            }
             Self::Interval { op, lhs, rhs } => write!(f, "{lhs}{}{rhs}", op.inspect()),
             Self::Subr(s) => write!(f, "{s}"),
             Self::TypeApp { spec, args } => write!(f, "{spec}{args}"),

compiler/erg_parser/desugar.rs

@@ -992,6 +992,17 @@ impl Desugarer {
                 insertion_idx += 1;
                 insertion_idx
             }
+            ParamPattern::Lit(l) => {
+                let lit = l.clone();
+                sig.pat = ParamPattern::Discard(Token::new(
+                    TokenKind::UBar,
+                    "_",
+                    l.ln_begin().unwrap(),
+                    l.col_begin().unwrap(),
+                ));
+                sig.t_spec = Some(TypeSpecWithOp::new(COLON, TypeSpec::enum_t_spec(vec![lit])));
+                insertion_idx
+            }
             _ => insertion_idx,
         }
     }