Re: glr2.cc compile errors under Windows

[Hans Åberg]

> On 21 Nov 2021, at 13:02, Jot Dot <jotdot@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.