I suppose the question is more "should reinterpret_cast be defined behavior"  (if you meet all memory requirements) regardless of type.
And my argument is it should.
From: Std-Proposals <std-proposals-bounces@lists.isocpp.org> on behalf of Thiago Macieira via Std-Proposals <std-proposals@lists.isocpp.org>
Sent: Tuesday, August 26, 2025 3:47:46 AM
To: std-proposals@lists.isocpp.org <std-proposals@lists.isocpp.org>; Paul Caprioli <paul@hpkfft.com>
Cc: Thiago Macieira <thiago@macieira.org>
Subject: Re: [std-proposals] TBAA and extended floating-point types
 
On Sunday, 24 August 2025 23:07:32 Pacific Daylight Time Paul Caprioli wrote:
> > As I pointed out in the other email: the choice here should be UTF-16, not
>
> UTF-8. That would get immediate and unconverted access to ICU, Win32 and
> Cocoa/CoreFoundation APIs.
>
> Sorry, but I'm not seeing how this relates to extended floating-point types.

It doesn't. This portion of the thread changed from discussing aliasing double
and std::float16_t to discussing aliasing char and char8_t, which then led to
the discussion of what encodings SG16 and the Standard should be looking into.

--
Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org
  Principal Engineer - Intel Platform & System Engineering