Switch return type of main from 'void' to 'int' #54628
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keith-packard
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As both C and C++ standards require applications running under an OS to return 'int', adapt that for Zephyr to align with those standard. This also eliminates errors when building with clang when not using -ffreestanding, and reduces the need for compiler flags to silence warnings for both clang and gcc Signed-off-by: Keith Packard <keithp@keithp.com>
As both C and C++ standards require applications running under an OS to
return 'int', adapt that for Zephyr to align with those standard. This also
eliminates errors when building with clang when not using -ffreestanding,
and reduces the need for compiler flags to silence warnings for both clang
and gcc.
Most of these changes were automated using coccinelle with the following
script:
@@
@@
- void
+ int
main(...) {
...
- return;
+ return 0;
...
}
Approximately 40 files had to be edited by hand as coccinelle was unable to
fix them.
Signed-off-by: Keith Packard <keithp@keithp.com>
These changes were automated using coccinelle with the following
script:
@@
@@
- void
+ int
main(...) {
...
- return;
+ return 0;
...
}
Signed-off-by: Keith Packard <keithp@keithp.com>
Looks like switching the main return value to int means that stack frame persists and increases stack usage by a few bytes. Increase the main stack size to avoid overflows. Signed-off-by: Keith Packard <keithp@keithp.com>
These flags were added to avoid warnings when main was declared to return void. Now that main returns int, those warnings will flag errors. Signed-off-by: Keith Packard <keithp@keithp.com>
Remove RETURN_FROM_MAIN macro which performed control flow, violating compliance tests. Replace with explicit use of posix_exit_main or return as appropriate. Signed-off-by: Keith Packard <keithp@keithp.com>
Add a paragraph explaining the change from void main(void) to int main(void) and the requirement for main functions to return zero. Signed-off-by: Keith Packard <keithp@keithp.com>
This applies the coccinelle script to another set of files: samples/bluetooth/bthome_sensor_template/src/main.c samples/boards/stm32/power_mgmt/standby_shutdown/src/main.c samples/drivers/smbus/src/main.c samples/drivers/virtualization/ivshmem/doorbell/src/ivshmem.c samples/fuel_gauge/max17048/src/main.c samples/hello_world/src/main.c samples/sensor/proximity_polling/src/main.c samples/subsys/logging/ble_backend/src/main.c tests/drivers/build_all/mfd/src/main.c Signed-off-by: Keith Packard <keithp@keithp.com>
Contributor
Author
rebased, repaired and re-pushed. |
nordicjm
approved these changes
Apr 13, 2023
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There was a problem hiding this comment.
This will need to be removed but it can be done in a later commit, no point holding this up anymore:
config CPP_MAIN
bool "C++ main() function definition"
help
This option instructs the Zephyr kernel to call the 'int main(void)'
instead of the 'void main(void)', which is the default main() type
for Zephyr.
C++ does not allow the main() to be defined with 'void' return type,
and any applications defining its main() in a C++ source file must
enable this option.
CC @stephanosio
And ./arch/posix/include/posix_cheats.h too
stephanosio
approved these changes
Apr 13, 2023
Member
Yes, I will open a follow-up PR. |
jfischer-no
approved these changes
Apr 13, 2023
cfriedt
approved these changes
Apr 13, 2023
Contributor
Author
|
I just realized that we can add |
20 tasks
This was referenced May 1, 2023
yashi
added a commit
to yashi/st-l6470
that referenced
this pull request
Apr 22, 2024
Since zephyrproject-rtos/zephyr#54628, Zephyr's main() returns int. Signed-off-by: Yasushi SHOJI <yashi@spacecubics.com>
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As both C and C++ standards require applications running under an OS to
return 'int', adapt that for Zephyr to align with those standard. This also
eliminates errors when building with clang when not using -ffreestanding,
and reduces the need for compiler flags to silence warnings for both clang
and gcc.
Related discussion: #54336 (comment)