Compiling with CONFIG_STD_C23 produces error

[Barto22]

Describe the bug

I was trying to port USB HID mouse example to my app which uses some other library which compiles with C23 standard so I enable this option in prj.conf. After that I have error from devicetree, the same for USB HID mouse sample app just after adding this CONFIG_STD_C23=y config.

error.txt

Regression

• This is a regression.

Steps to reproduce

west build -p always -b stm32f4_disco samples/subsys/usb/hid-mouse -- -DCONFIG_STD_C23=y

Relevant log output

Full build log is in attachmen because is too long.

Impact

Functional Limitation – Some features not working as expected, but system usable.

Environment

• OS Ubuntu 24.04
• Zephyr SDK
• Latest main zephyr branch

Additional Context

I was trying to build for stm32f4_disco and nrf52840dk.

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[pdgendt]

The issue appears to be cause by macros here:

zephyr/subsys/usb/device_next/class/usbd_hid.c

Lines 771 to 774 in 1814b90

	.in_ep = HID_IN_EP_DEFINE(n, false, true), \
	.hs_in_ep = HID_IN_EP_DEFINE(n, true, true), \
	.out_ep = HID_OUT_EP_DEFINE_OR_ZERO(n, false, true), \
	.hs_out_ep = HID_OUT_EP_DEFINE_OR_ZERO(n, true, true), \

Which expand to

COND_CODE_1(true, (/*...*/), (/*...*/))`

In C23 the booleans true and false are no longer defined as 1 and 0.

[henrikbrixandersen]

In C23 the booleans true and false are no longer defined as 1 and 0.

I expect this will result in issues in other parts of the codebase as well.

[jfischer-no]

In C23 the booleans true and false are no longer defined as 1 and 0.

But of course they are, and will continue to be in the future.
"The keywords false and true are constants of type bool with a value of 0 for false and 1 for
true."

[pdgendt]

In C23 the booleans true and false are no longer defined as 1 and 0.

But of course they are, and will continue to be in the future. "The keywords false and true are constants of type bool with a value of 0 for false and 1 for true."

Please open the link and see that the defines are guarded, in C23 they are no longer expanded in the C preprocessor. They evaluate to 1 and 0, true.

[jfischer-no]

In C23 the booleans true and false are no longer defined as 1 and 0.

But of course they are, and will continue to be in the future. "The keywords false and true are constants of type bool with a value of 0 for false and 1 for true."

Please open the link and see that the defines are guarded, in C23 they are no longer expanded in the C preprocessor. They evaluate to 1 and 0, true.

The C23 standard says they are predefined constants of type bool. Zephyr SDK, e.g. 12.2, sets __bool_true_false_are_defined to 1 and defines both, false and true.