Implement char8_t compatibility remedies

[miscco]

Description

This addresses #59 by adding the missing deleted overloads to basic_ostream<meow>::operator<<(bark)

The other changesin that proposal have already been implemented. As there was no switch the changes have been implemented unconditionally.

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[CaseyCarter]

Note to other reviewers: This means the char8_t overloads continue to be deleted even in sub-C++20 mode (e.g., if compiling with e.g. /std:c++17 /Zc:char8_t). I'm fine with this inconsistent behavior of char8_t vs. char16_t/char32_t, shout if you are not.

[DBJDBJ]

That's fine, in any case only "he who likes pain" will use char8_t in C++20... Now, where is that Jens Gustedt pdf on modern C ... sorry talking to myself, have to go now... Good work Casey, thanks a lot, see you ...

[miscco]

Thanks a lot @CaseyCarter.
Can't wait until the tests are ported so that you dont have to do all the firefighting.

[CaseyCarter]

Can't wait until the tests are ported so that you dont have to do all the firefighting.

Heh - I grabbed this since (a) I implemented the original char8_t support in the STL, and (b) it seemed small enough that I could quickly throw together a test to validate that the now ill-formed stream insertion expressions are in fact ill-formed. Then I ran tests, and discovered this beauty:

void
print_log_value<wchar_t const*>::operator()( std::ostream& ostr, wchar_t const* t )
{
    ostr << ( t ? t : L"null string" );
}

in the Boost unit test library (reported at boostorg/test#249).

[miscco]

@CaseyCarter Thanks for the fix, although I would suggest to change it in a way compatible with #380 If it is ok for you I would rebase it on #380 and use the convention established there:

#ifndef _HAS_STREAM_INSERTIONS_REMOVED_BY_P1423
#define _HAS_STREAM_INSERTIONS_REMOVED_BY_P1423 (_HAS_FEATURES_REMOVED_IN_CXX20)
#endif // _HAS_STREAM_INSERTIONS_REMOVED_BY_P1423

and then guard those with

#if _HAS_STREAM_INSERTIONS_REMOVED_BY_P1423

Also is the paper really needed in the name?

[CaseyCarter]

@CaseyCarter Thanks for the fix, although I would suggest to change it in a way compatible with #380 ... Also is the paper really needed in the name?

We didn't give the macro name a ton of thought beyond the fact that only I thought BOGUS_STREAM_INSERTIONS was a good name. In context with #380, I believe _HAS_STREAM_INSERTIONS_REMOVED_IN_CXX20 works quite well. I'll change the macro name and default to (!_HAS_CXX20), and work with @StephanTLavavej on the details of defaulting to _HAS_FEATURES_REMOVED_IN_CXX20. (I think this will be ready to merge in a few hours, but haven't seen Stephan's PR for #380 yet, so we may do the integration in #380 rather than here).

Does that sound good?

[miscco]

I am totally fine with the name.

[CaseyCarter]

Thanks for your contribution!