From e9d0642b29ed3facfa1c0c2ad6029629ca95af1b Mon Sep 17 00:00:00 2001
From: Shunsuke Shibayama <sbym1346@gmail.com>
Date: Sun, 4 Dec 2022 11:44:13 +0900
Subject: [PATCH] Fix a desugaring bug

---
 compiler/erg_parser/ast.rs     |  8 +++++++-
 compiler/erg_parser/desugar.rs | 11 +++++++++++
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/compiler/erg_parser/ast.rs b/compiler/erg_parser/ast.rs
index 2097ba8d..af8ecc7c 100644
--- a/compiler/erg_parser/ast.rs
+++ b/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}"),
diff --git a/compiler/erg_parser/desugar.rs b/compiler/erg_parser/desugar.rs
index e7adc2e0..7548998c 100644
--- a/compiler/erg_parser/desugar.rs
+++ b/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,
         }
     }