Argument -fshort-enums and __attribute__((packed)) on enums are ignored

[whypet]

When specifying -fshort-enums in the command line or marking an enum with __attribute__((packed)), the size of the enum should be smaller than an int if all the values in the enum fit in a short or a char, however the size of the enum is 4 bytes.
I'm facing this issue on the LLVM 17.0.3 Win32 builds.

Repro

main.c:

#include <assert.h>

enum __attribute__((packed)) BYTE_ENUM {
	A = 0,
	B = 1
};

static_assert(sizeof(enum BYTE_ENUM) == 1, "Size of BYTE_ENUM should be 1 byte.");

Command line: clang main.c -fshort-enums (or clang main.c since we are adding the attribute to the enum anyway)

Screenshot

[llvmbot]

@llvm/issue-subscribers-clang-codegen

Author: wipet (whypet)

When specifying `-fshort-enums` in the command line or marking an enum with `__attribute__((packed))`, the size of the enum should be smaller than an `int` if all the values in the enum fit in a `short` or a `char`, however the size of the enum is 4 bytes. I'm facing this issue on the LLVM 17.0.3 Win32 builds.

Repro

main.c:

#include <assert.h>

enum __attribute__((packed)) BYTE_ENUM {
	A = 0,
	B = 1
};

static_assert(sizeof(enum BYTE_ENUM) == 1, "Size of BYTE_ENUM should be 1 byte.");

Command line: clang main.c -fshort-enums (or clang main.c since we are adding the attribute to the enum anyway)

Screenshot

[thomasfinchbr]

Hi, is this issue still open?

[whypet]

Seems like it was fixed so I'll close this issue. Can't reproduce it anymore on my machine.

clang version 20.1.6
Target: x86_64-chimera-linux-musl