From 91f52c12ff69716b09a68afb68752fbfe8602e8a Mon Sep 17 00:00:00 2001
From: Lai-YT <381xvmvbib@gmail.com>
Date: Fri, 15 Sep 2023 14:34:13 +0800
Subject: [PATCH] Enhance error message verbosity

---
 parser.y | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/parser.y b/parser.y
index bad5f7d2..f74ae21e 100644
--- a/parser.y
+++ b/parser.y
@@ -38,6 +38,12 @@ extern std::unique_ptr<AstNode> program;
 %define api.value.automove
 // This guarantees that headers do not conflict when included together.
 %define api.token.prefix {TOK_}
+// Have messages report the unexpected token, and possibly the expected ones.
+// Without this, the error message is always only "syntax error".
+%define parse.error verbose
+// Improve syntax error handling, as LALR parser might perform additional
+// parser stack reductions before discovering the syntax error.
+%define parse.lac full
 
 %token <int> NUM
 %token <std::string> ID