From 8a6cfbae9078c2095cb242e903dcac1c38c2fdb0 Mon Sep 17 00:00:00 2001
From: Ryo Nihei <nihei.dev@gmail.com>
Date: Wed, 30 Mar 2022 21:51:06 +0900
Subject: [PATCH] Fix error messages

---
 grammar/grammar.go | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/grammar/grammar.go b/grammar/grammar.go
index 1a09a22..bc8cc6b 100644
--- a/grammar/grammar.go
+++ b/grammar/grammar.go
@@ -274,7 +274,7 @@ func findUsedAndUnusedSymbols(root *spec.RootNode) (*usedAndUnusedSymbols, error
 			}
 			continue
 		}
-		return nil, fmt.Errorf("a definition of unused production was not found: %v", sym)
+		return nil, fmt.Errorf("unknown symbol: a symbol must be a terminal symbol or a non-terminal symbol: %v", sym)
 	}
 
 	return &usedAndUnusedSymbols{
@@ -816,7 +816,7 @@ func (b *GrammarBuilder) genProductionsAndActions(root *spec.RootNode, symTabAnd
 					if len(dir.Parameters) == 0 {
 						b.errs = append(b.errs, &verr.SpecError{
 							Cause:  semErrDirInvalidParam,
-							Detail: "'ast' directive needs at least one symbol position parameter",
+							Detail: "'ast' directive needs at least one parameter",
 							Row:    dir.Pos.Row,
 							Col:    dir.Pos.Col,
 						})