Allow integers with up to 18 digits in OPL parser

See #336.

Author: joto

include/osmium/io/detail/opl_parser_functions.hpp

@@ -206,9 +206,8 @@ namespace osmium {
                 *data = s;
             }
 
-            // Arbitrary limit how long integers can get
             enum {
-                max_int_len = 16
+                max_int_len = std::numeric_limits<int64_t>::digits10 + 1
             };
 
             template <typename T>

test/t/io/test_opl_parser.cpp

@@ -260,6 +260,8 @@ TEST_CASE("Parse OPL: integer") {
     REQUIRE(test_parse_int("-1x") == -1);
     REQUIRE(test_parse_int("1234567890123x") == 1234567890123);
     REQUIRE(test_parse_int("-1234567890123x") == -1234567890123);
+    REQUIRE(test_parse_int("999999999999999999x") == 999999999999999999);
+    REQUIRE(test_parse_int("-999999999999999999x") == -999999999999999999);
 
     REQUIRE_THROWS_WITH(test_parse_int(""),
                         "OPL error: expected integer");