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From: "dhylands at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/114928] New: #pragma packed(push,1) should give the same
 warning as __attribute__((packed))
Date: Thu, 02 May 2024 22:52:00 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D114928

            Bug ID: 114928
           Summary: #pragma packed(push,1) should give the same warning as
                    __attribute__((packed))
           Product: gcc
           Version: 13.2.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: dhylands at gmail dot com
  Target Milestone: ---

Created attachment 58091
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=3D58091&action=3Dedit
File that compiles with no warnings

I'm using the ARM Toolchain
arm-gnu-toolchain-13.2.Rel1-x86_64-aarch64-none-linux-gnu/bin/aarch64-none-=
linux-gnu-g++

running on Ubuntu 20.04

If I delcare my structure using:

struct Foo {
    char y;
    int x;
} __attribute__((packed));

then the compiler correctly gives me a warning about taking the address of a
packed member:

warning: taking address of packed member of =E2=80=98Foo=E2=80=99 may resul=
t in an unaligned
pointer value [-Waddress-of-packed-member]

However, if I change the structure to use #pragma pack(push, 1)=20

#pragma pack(push, 1)
struct Foo {
    char y;
    int x;
};
#pragma pack(pop)

then I don't get the warning (and my bug is that it should give the same
warning).

In either case the member offsets and structure size are the same.=