[parser] parser: fix signed num will parse error when it encounter tw…

…o's complement min (pingcap#905)

parser/parser.y

@@ -11452,9 +11452,18 @@ SignedNum:
 	{
 		$$ = $2
 	}
-|	'-' Int64Num
+|	'-' NUM
 	{
-		$$ = -$2.(int64)
+		unsigned_num := getUint64FromNUM($2)
+		if unsigned_num > 9223372036854775808 {
+			yylex.AppendError(yylex.Errorf("the Signed Value should be at the range of [-9223372036854775808, 9223372036854775807]."))
+			return 1
+		} else if unsigned_num == 9223372036854775808 {
+			signed_one := int64(1)
+			$$ = signed_one << 63
+		} else {
+			$$ = -int64(unsigned_num)
+		}
 	}
 
 DropSequenceStmt:

parser/parser_test.go

@@ -861,6 +861,13 @@ AAAAAAAAAAAA5gm5Mg==
 		// for alter instance.
 		{"ALTER INSTANCE RELOAD TLS", true, "ALTER INSTANCE RELOAD TLS"},
 		{"ALTER INSTANCE RELOAD TLS NO ROLLBACK ON ERROR", true, "ALTER INSTANCE RELOAD TLS NO ROLLBACK ON ERROR"},
+
+		// for create sequence with signed value especially with Two's Complement Min.
+		// for issue #17948
+		{"CREATE SEQUENCE seq INCREMENT - 9223372036854775807", true, "CREATE SEQUENCE `seq` INCREMENT BY -9223372036854775807"},
+		{"CREATE SEQUENCE seq INCREMENT - 9223372036854775808", true, "CREATE SEQUENCE `seq` INCREMENT BY -9223372036854775808"},
+		{"CREATE SEQUENCE seq INCREMENT -9223372036854775808", true, "CREATE SEQUENCE `seq` INCREMENT BY -9223372036854775808"},
+		{"CREATE SEQUENCE seq INCREMENT -9223372036854775809", false, ""},
 	}
 	s.RunTest(c, table)
 }