better error message (pingcap#1) (pingcap#133)

lexer.go

@@ -123,11 +123,17 @@ func (s *Scanner) stmtText() string {
 // Scanner satisfies yyLexer interface which need this function.
 func (s *Scanner) Errorf(format string, a ...interface{}) {
 	str := fmt.Sprintf(format, a...)
-	val := s.r.s[s.r.pos().Offset:]
+	col := s.r.p.Col
+	startPos := s.stmtStartPos
+	if s.r.s[startPos] == '\n' {
+		startPos++
+		col--
+	}
+	val := s.r.s[startPos:]
 	if len(val) > 2048 {
 		val = val[:2048]
 	}
-	err := fmt.Errorf("line %d column %d near \"%s\"%s (total length %d)", s.r.p.Line, s.r.p.Col, val, str, len(s.r.s))
+	err := fmt.Errorf("line %d column %d near \"%s\"%s (total length %d)", s.r.p.Line, col, val, str, len(s.r.s))
 	s.errs = append(s.errs, err)
 }
 

parser_test.go

@@ -1833,13 +1833,13 @@ func (s *testParserSuite) TestHintError(c *C) {
 	stmt, warns, err := parser.Parse("select /*+ tidb_unknow(T1,t2) */ c1, c2 from t1, t2 where t1.c1 = t2.c1", "", "")
 	c.Assert(err, IsNil)
 	c.Assert(len(warns), Equals, 1)
-	c.Assert(warns[0].Error(), Equals, "line 1 column 32 near \" c1, c2 from t1, t2 where t1.c1 = t2.c1\" (total length 71)")
+	c.Assert(warns[0].Error(), Equals, "line 1 column 32 near \"select /*+ tidb_unknow(T1,t2) */ c1, c2 from t1, t2 where t1.c1 = t2.c1\" (total length 71)")
 	c.Assert(len(stmt[0].(*ast.SelectStmt).TableHints), Equals, 0)
 	stmt, warns, err = parser.Parse("select /*+ tidb_unknow(T1,t2, 1) TIDB_INLJ(t1, T2) */ c1, c2 from t1, t2 where t1.c1 = t2.c1", "", "")
 	c.Assert(len(stmt[0].(*ast.SelectStmt).TableHints), Equals, 0)
 	c.Assert(err, IsNil)
 	c.Assert(len(warns), Equals, 1)
-	c.Assert(warns[0].Error(), Equals, "line 1 column 53 near \" c1, c2 from t1, t2 where t1.c1 = t2.c1\" (total length 92)")
+	c.Assert(warns[0].Error(), Equals, "line 1 column 53 near \"select /*+ tidb_unknow(T1,t2, 1) TIDB_INLJ(t1, T2) */ c1, c2 from t1, t2 where t1.c1 = t2.c1\" (total length 92)")
 	stmt, _, err = parser.Parse("select c1, c2 from /*+ tidb_unknow(T1,t2) */ t1, t2 where t1.c1 = t2.c1", "", "")
 	c.Assert(err, NotNil)
 	stmt, _, err = parser.Parse("select1 /*+ TIDB_INLJ(t1, T2) */ c1, c2 from t1, t2 where t1.c1 = t2.c1", "", "")
@@ -1850,6 +1850,15 @@ func (s *testParserSuite) TestHintError(c *C) {
 	c.Assert(err, IsNil)
 }
 
+func (s *testParserSuite) TestErrorMsg(c *C) {
+	parser := New()
+	_, _, err := parser.Parse("select1 1", "", "")
+	c.Assert(err.Error(), Equals, "line 1 column 7 near \"select1 1\" (total length 9)")
+
+	_, _, err = parser.Parse("select a1 from t1\nwhere t1.a2 = 1;\nselect1 1", "", "")
+	c.Assert(err.Error(), Equals, "line 3 column 7 near \"select1 1\" (total length 44)")
+}
+
 func (s *testParserSuite) TestOptimizerHints(c *C) {
 	parser := New()
 	stmt, _, err := parser.Parse("select /*+ tidb_SMJ(T1,t2) tidb_smj(T3,t4) */ c1, c2 from t1, t2 where t1.c1 = t2.c1", "", "")