Are C++14 digit separators allowed in user defined literals?

While clang compiles the following line, g++ 6.1 complains about the digit separator (see live example on Coliru): ``` auto time = 01'23s; ``` Which compiler, if any, is correct according to the C++14 standard (N3796)? Otherwise, is allowing digit separators (§2.14.2) just an implementation detail in the user-defined literals (§2.14.8) of the `<chrono>` library (§20.12.5.8)? IMHO it should be not, since these literals are defined on `unsigned long long` parameters. I remember Howard Hinnant using `10'000s` as an example during his CppCon 2016 talk "A `<chrono>` tutorial" (at about 42 minutes in his talk). (Please note, that I did not intend to code "1 minute and 23 seconds", which is only correct by accident, since the octal literal 0123 is 64 + 16 + 3 == 83. For that purpose I should write ``` auto time = 1min + 23s; ``` but that possible misleading interpretation is not part of the question.)