From c4417f4ecd678b4a69263d7a56acbd78dcc24723 Mon Sep 17 00:00:00 2001
From: lysu <sulifx@gmail.com>
Date: Fri, 7 Sep 2018 10:27:50 +0800
Subject: [PATCH] parser: fix single line comment end with newline (#7612)
 (#7635)

---
 parser/lexer.go      | 14 ++++++++------
 parser/lexer_test.go |  4 ++++
 2 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/parser/lexer.go b/parser/lexer.go
index 70ff48c7fa368..6ceb1e062423d 100644
--- a/parser/lexer.go
+++ b/parser/lexer.go
@@ -307,12 +307,14 @@ func startWithSharp(s *Scanner) (tok int, pos Pos, lit string) {
 
 func startWithDash(s *Scanner) (tok int, pos Pos, lit string) {
 	pos = s.r.pos()
-	if strings.HasPrefix(s.r.s[pos.Offset:], "-- ") {
-		s.r.incN(3)
-		s.r.incAsLongAs(func(ch rune) bool {
-			return ch != '\n'
-		})
-		return s.scan()
+	if strings.HasPrefix(s.r.s[pos.Offset:], "--") {
+		remainLen := len(s.r.s[pos.Offset:])
+		if remainLen == 2 || (remainLen > 2 && unicode.IsSpace(rune(s.r.s[pos.Offset+2]))) {
+			s.r.incAsLongAs(func(ch rune) bool {
+				return ch != '\n'
+			})
+			return s.scan()
+		}
 	}
 	if strings.HasPrefix(s.r.s[pos.Offset:], "->>") {
 		tok = juss
diff --git a/parser/lexer_test.go b/parser/lexer_test.go
index a2fe701a41d1f..e2cb06681584f 100644
--- a/parser/lexer_test.go
+++ b/parser/lexer_test.go
@@ -166,6 +166,10 @@ SELECT`, selectKwd},
 SELECT`, selectKwd},
 		{"#comment\n123", intLit},
 		{"--5", int('-')},
+		{"--\nSELECT", selectKwd},
+		{"--\tSELECT", 0},
+		{"--\r\nSELECT", selectKwd},
+		{"--", 0},
 	}
 	runTest(c, table)
 }