#588 __attribute__((packed)) seemingly ignored

[Jesse]

For some reason, whenever I try and pack my structs using attribute((packed)), the default padding remains.

For example:

#include <iostream>

struct testa
{
    char x;
    long y;
};

struct __attribute__((__packed__)) testb
{
    char x;
    long y;
};

int main()
{
    std::printf("no __attribute__: %d\nwith __attribute__: %d", sizeof(testa), sizeof(testb));
}

The values of both no attribute and attribute is 8, though I would expect it to be 8 and 5.

If I use #pragma pack(push, 1) and #pragma pack(pop), I get the expected result.

[Rob Turk]

I ran into a similar issue. Looks like a gcc bug:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=54589

Fix for me was to use "attribute((gcc_struct,packed))" instead
note: attribute should have two underscores before and after, SF editor messes that up