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From: "steve+gcc at tecwec dot eu" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug c++/36566] Cannot bind packed field
Date: Fri, 31 Dec 2021 15:11:13 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D36566

Eric Estievenart <steve+gcc at tecwec dot eu> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |steve+gcc at tecwec dot eu

--- Comment #14 from Eric Estievenart <steve+gcc at tecwec dot eu> ---
What about:
struct S
{
        int i;
}  __attribute__((__packed__)) __attribute((aligned(8)));

void f( S* s )
{
        int& i =3D s->i; // Error here
}

S::i is obviously properly aligned, the compiler should know it and accept =
the
referencing.

As for the argument 'the field might be unaligned and this would violate...=
 and
crash...', I don=C2=B4t really agree. The compiler knows the arch, the alig=
nment,
and it can decide:
- to emit an error if unaligned(or unknown) if alignment required by arch
- to emit a warning on other arch

Note by the way that this seems accepted by clang...=