sys/cpp_new_delete: handle allocation failures

[maribu]

Contribution description

If exceptions are supported, throw an std::bad_alloc on allocation failure.

If not, panic on allocation failure.

Testing procedure

Allocations should now fail as expected. E.g. the test in tests/sys/cpp11_thread can both easily trigger allocation failures and has a very interesting failure mode.

With this fix, the failure mode should be more boring.

Issues/PRs references

Found in #22417

Declaration of AI-Tools / LLMs usage:

AI-Tools / LLMs that were used are:

• none

[riot-ci]

Murdock results

❌ FAILED

19abdf9 sys/cpp_new_delete: handle allocation failures

Build failures (3)

Application	Target	Toolchain	Runtime (s)	Worker
tests/core/rmutex_cpp	atmega256rfr2-xpro	gnu	1.43	mobi1
tests/pkg/etl	atmega256rfr2-xpro	gnu	0.85	mobi6
tests/sys/cpp_ctors	atmega256rfr2-xpro	gnu	0.39	mobi6

Artifacts

[crasbe]

Tested with the Nucleo-G031K8 with the timer PR applied.

It still crashes because after this I can't flash it before resetting/power cycling the microcontroller.

cbuec@W11nMate:~/RIOTstuff/riot-vanillaice/RIOT$ BOARD=nucleo-g031k8 make -C tests/sys/cpp11_thread/ flash test -j
make: Entering directory '/home/cbuec/RIOTstuff/riot-vanillaice/RIOT/tests/sys/cpp11_thread'
Building application "tests_cpp11_thread" for "nucleo-g031k8" with CPU "stm32".
...
Done flashing
r
/home/cbuec/RIOTstuff/riot-vanillaice/RIOT/dist/tools/pyterm/pyterm -p "/dev/ttyACM0" -b "115200" -ln "/tmp/pyterm-cbuec" -rn "2026-06-25_10.18.17-tests_cpp11_thread-nucleo-g031k8" --no-reconnect --noprefix --no-repeat-command-on-empty-line
Connect to serial port /dev/ttyACM0
Welcome to pyterm!
Type '/exit' to exit.
READY
s
START
main(): This is RIOT! (Version: 2026.07-devel-391-gd242c6-sys/cpp_new_delete/error-handling)

************ C++ thread test ***********
Creating one thread and passing an argument ...
#! exit 1: powering off
Timeout in expect script at "child.expect_exact("Done")" (tests/sys/cpp11_thread/tests/01-run.py:17)

make: *** [/home/cbuec/RIOTstuff/riot-vanillaice/RIOT/makefiles/tests/tests.inc.mk:32: test] Error 1
make: Leaving directory '/home/cbuec/RIOTstuff/riot-vanillaice/RIOT/tests/sys/cpp11_thread'

[maribu]

I wonder if the hang is due to an uncaught exception (I see no code that would catch the bad alloc exception in either the thread implementation nor in the test app), or if that is the panic handler.

It is good that there now is a defined crash, rather than the code keeping to run on corrupted memory. But the complete absense of any helpful indication of what went wrong in the log is a major footgun that I need to address first.

[crasbe]

Setting the THREAD_STACKSIZE_MAIN to 512 makes it run successfully.

Enabling DEVELHELP does not give additional information unfortunately.