> On 21 Nov 2021, at 13:02, Jot Dot <jot...@shaw.ca> wrote: > >> 53 #if defined __cplusplus >> 54 # define YY_CPLUSPLUS __cplusplus >> 55 #else >> 56 # define YY_CPLUSPLUS 199711L >> 57 #endif >> >> Please check why your compiler does not define __cplusplus. Compliant >> compilers >> must define it properly so that we can know what version of C++17 we're in. >> See https://en.cppreference.com/w/cpp/preprocessor/replace#Predefined_macros. > > > It is defined. Just not what we think it should be. It is 199711L
Some compilers do this, also Apple clang uses C++98. So one must use an option -std=c++20 or something. The default on GCC 11 is C++17, and on Clang 12 it is C++14.
