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	Wed, 30 Oct 2024 09:00:46 -0700 (PDT)
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Subject:	Re: g++ 12 -std=gnu++20
In-Reply-To:	<48e51b50-63db-4b14-b321-46942e40862e@SystematicSW.ab.ca>
Date:	Wed, 30 Oct 2024 17:00:44 +0100
Cc:	Brian Inglis <Brian DOT Inglis AT SystematicSW DOT ab DOT ca>
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From:	Dimitry Andric via Cygwin <cygwin AT cygwin DOT com>
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On 30 Oct 2024, at 16:06, Brian Inglis via Cygwin <cygwin AT cygwin DOT com> wrote:
> Trying to update a package using c++ (requires gcc 12.4+ for adequate c++ 2020 support) and getting confusing error messages.
> 
> It appears that noexcept in the header files may here redefined by the compiler or headers as __GLIBC_NOEXCEPT.
> Those errors look to me like a failure to detect that *glibc* is not available.
> Or is *GLIBCXX* actually *glib* for *cxx*, so this could be a library or compiler issue?
> 
> It appears that str::size() should be a constexpr but something messes it up.
> Or is something else going on here?

As far as I can determine, even a simple example does not work for gcc 12:

#include<string>
#include<cassert>

constexpr bool foo()
{
  std::string str2{"abcwe"};
  return str2.size()==5;
}

static_assert(foo());

int main()
{
  assert(foo());
}

As far as I know, there is no gcc 13 for Cygwin yet, but on Linux and FreeBSD this does compile with gcc 13.

-Dimitry


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