Compile error in byteorder.h

[surfskidude]

Discussed in #44190

^{Originally posted by surfskidude March 24, 2022}
I cloned the latest today and I got a compile error when I compiled my existing code, which includes net/socket.h

In file included from /home/build/zephyrproject/zephyr/include/net/net_ip.h:27,
from /home/build/zephyrproject/zephyr/include/net/socket.h:27,
/home/build/zephyrproject/zephyr/include/sys/byteorder.h:22:36: error: expected declaration specifiers or ‘...’ before ‘(’ token
22 | #define __bswap_16(x) ((uint16_t) ((((x) >> 8) & 0xff) | (((x) & 0xff) << 8)))
| ^
/home/build/zephyrproject/zephyr/include/sys/byteorder.h:26:36: error: expected declaration specifiers or ‘...’ before ‘(’ token
26 | #define __bswap_32(x) ((uint32_t) ((((x) >> 24) & 0xff) |
| ^
/home/build/zephyrproject/zephyr/include/sys/byteorder.h:36:36: error: expected declaration specifiers or ‘...’ before ‘(’ token
36 | #define __bswap_64(x) ((uint64_t) ((((x) >> 56) & 0xff) |
| ^

Build:
west build -p auto -b native_posix_64 myproject

[henrikbrixandersen]

Please include further details. Which host OS, which compiler etc. All of this is requested if you fill out the bug report issue template.

[mbolivar-nordic]

Closing for now due to insufficient information to categorize this as a bug. Please reopen with additional information if you believe this to be a bug, including steps to reproduce.

[surfskidude]

If you look at the end of the above you see: west build -p auto -b native_posix_64 myproject

[henrikbrixandersen]

If you look at the end of the above you see: west build -p auto -b native_posix_64 myproject

Quite difficult to reproduce myproject.

[surfskidude]

Just include net/socket.h in any C file and it will fail with native_posix_64

[mbolivar-nordic]

Does not reproduce on my machine.

$ git diff
diff --git a/samples/hello_world/src/main.c b/samples/hello_world/src/main.c
index 987728bbf2..c442b25b75 100644
--- a/samples/hello_world/src/main.c
+++ b/samples/hello_world/src/main.c
@@ -5,6 +5,7 @@
  */
 
 #include <zephyr.h>
+#include <net/socket.h>
 
 void main(void)
 {
(west-0.13) scarlet: ~/zp/zephyr (west-project-maintainers) mbolivar
$ west build -p -b native_posix_64 samples/hello_world 
-- west build: making build dir /home/mbolivar/zp/zephyr/build pristine
-- west build: generating a build system
loading initial cache file /home/mbolivar/zp/xtra/initial-cache.cmake
Loading Zephyr default modules (Zephyr base).
-- Application: /home/mbolivar/zp/zephyr/samples/hello_world
-- Found Python3: /home/mbolivar/.virtualenvs/west-0.13/bin/python3.10 (found suitable exact version "3.10.4") found components: Interpreter 
-- Cache files will be written to: /home/mbolivar/.cache/zephyr
-- Zephyr version: 3.0.99 (/home/mbolivar/zp/zephyr)
-- Found west (found suitable version "0.13.0a1", minimum required is "0.7.1")
-- Board: native_posix_64
-- Found dtc: /usr/bin/dtc (found suitable version "1.6.1", minimum required is "1.4.6")
-- Found toolchain: host (gcc/ld)
-- Found BOARD.dts: /home/mbolivar/zp/zephyr/boards/posix/native_posix/native_posix_64.dts
-- Generated zephyr.dts: /home/mbolivar/zp/zephyr/build/zephyr/zephyr.dts
-- Generated devicetree_unfixed.h: /home/mbolivar/zp/zephyr/build/zephyr/include/generated/devicetree_unfixed.h
-- Generated device_extern.h: /home/mbolivar/zp/zephyr/build/zephyr/include/generated/device_extern.h
-- Including generated dts.cmake file: /home/mbolivar/zp/zephyr/build/zephyr/dts.cmake
Parsing /home/mbolivar/zp/zephyr/Kconfig
Loaded configuration '/home/mbolivar/zp/zephyr/boards/posix/native_posix/native_posix_64_defconfig'
Merged configuration '/home/mbolivar/zp/zephyr/samples/hello_world/prj.conf'
Configuration saved to '/home/mbolivar/zp/zephyr/build/zephyr/.config'
Kconfig header saved to '/home/mbolivar/zp/zephyr/build/zephyr/include/generated/autoconf.h'
-- The C compiler identification is GNU 11.2.0
-- The CXX compiler identification is GNU 11.2.0
-- The ASM compiler identification is GNU
-- Found assembler: /usr/lib/ccache/bin/gcc
-- Configuring done
-- Generating done
-- Build files have been written to: /home/mbolivar/zp/zephyr/build
-- west build: building application
[1/97] Preparing syscall dependency handling

[2/97] Generating include/generated/version.h
-- Zephyr version: 3.0.99 (/home/mbolivar/zp/zephyr), build: zephyr-v3.0.0-2355-ga54006612448
[93/97] Linking C executable zephyr/zephyr_pre0.elf

[97/97] Linking C executable zephyr/zephyr.elf

[surfskidude]

Create and compile a C file with the two following lines and you will get the error:

#include <net/socket.h>
#include <byteswap.h>

[de-nordic]

byteswap.h collides with byteorder.h (tested on amd64), because byteorder.h defines preprocessor macro named __bswap_16 and byteswap.h tries to define inline function of the same identifier; the order of inclusion causes the identifier in function definition, from byteswap.h, to be substituted with replacement-list of macro __bswap_16, from byteorder.h.
Then compiler kicks in just to find a broken function definition, and complains.
Do you really need the byteswap.h?

[de-nordic]

On my build setup (Ubuntu 20.04, kernel 5.4, gcc 9.4, libglib2.0-dev:2.64.6-1~ubuntu20.04.4) the byteswap.h (taken from /usr/include/bits/) provides all the __bswap_nn definition that are already covered by byteorder.h, I see no point on including byteswap.h after net/socket.h, which already includes byteorder.h.

[surfskidude]

We are using a common code base on multiple platforms. The net/socket is included by a special zephyr porting layer. byteswap.h is included by the generic code.

If you look at my initial comments at the top of this thread, we did not have this problem until recently so something changed in zephyr that broke this.

[rlubos]

Why did you assign me to this? It's not a networking problem.

[de-nordic]

@surfskidude What version of Zephyr, which commit are you using as base?
The files, net_ip.h and byteorder.h, does not seem to be touched in 3 or more years, in lines that could affect this.
Is it possible to just #ifdef inclussion of byteswap.h for Zephyr platform?

[mbolivar-nordic]

Why did you assign me to this? It's not a networking problem.

@aescolar I assigned you because it is a native posix issue

[mbolivar-nordic]

If you look at my initial comments at the top of this thread, we did not have this problem until recently so something changed in zephyr that broke this.

.. or something changed in your underlying platform, etc.

Notice how @de-nordic carefully specified their platform. It would really help if you could do the same

[surfskidude]

.. or something changed in your underlying platform, etc.

No, no changes were made to our code or build. I did a pull a few days ago so it's a recent Zephyr release. I have no idea what the old working Zephyr release version was, but it did work.

[mbolivar-nordic]

You may be convinced of that, and you are probably right, but I am trying to explain the difference between 1. you being right and 2. you convincing the upstream Zephyr developers that you are right by providing them with an example that they can actually reproduce instead of just repeating yourself ad nauseam.

[github-actions]

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[andrewleech]

For what it's worth, I encountered the same error message when compiling sections of the zephyr codebase on linux x64, gcc 9.4.0 (not using Zephyr SDK).

By comparing compile arguments between standard zephyr / west builds for native_posix_64 and my custom Makefile I narrowed the issue down to -std=c11

If I compile without -std=c11 it throws these error in zephyr/sys/byteorder.h, eg.

../../lib/zephyr/include/zephyr/sys/byteorder.h:20:36: error: expected declaration specifiers or ‘...’ before ‘(’ token
   20 | #define __bswap_16(x) ((uint16_t) ((((x) >> 8) & 0xff) | (((x) & 0xff) << 8)))

With -std=c11 it compiles fine.

[mkettn]

Hello,
I stumbled upon the same problem also for BOARD=native_posix[_64] ... on the contrary: BOARD=qemu_x86 works.
I get the same error and adding -std=c11 does not work for me, since I am using a C++ compiler.
zephyr is at most recent version on main (9ebb9ab) and I am using the Zephyr SDK v0.15.1

Since the posix native target is not that crucial for me, I'll just go with qemu. However, the problem still persists.

[aescolar]

For those facing this issue, and until it is fixed in Zephyr (where it should): One workaround which may work out of the box for you is to target native_sim instead of native_posix and select one of the embedded C libraries (for ex. CONFIG_PICOLIBC=y).