https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69905
Bug ID: 69905 Summary: Digit separators break literal operators Product: gcc Version: 6.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: public at alisdairm dot net Target Milestone: --- The following code fails to compile when the macro is defined: #include <chrono> using namespace std::literals; #if defined SHOW_BUG auto x = 1'23s #else auto x = 123s; #endif I /think/ this is a problem in the front-end, rather than the library, as the digit separator should not be visible to the library call.