Description
Description
The exception handling is undefined in RIOT.
Some modules and unit tests use exceptions, e.g. the riot::thread implementation from the cpp11_compat module and the according unit test.
Steps to reproduce the issue
I've created a unit test to demonstrate the current undefined behavior: jenswet@7940cbe
Expected results
All boards should give the following result:
************ C++ exception test ***********
Exceptions enabled
Exception catched
******************************************
Actual results
The native board does as expected:
RIOT native board initialized.
RIOT native hardware initialization complete.
Help: Press s to start test, r to print it is ready
READY
s
START
main(): This is RIOT! (Version: 2022.04-devel-20-g95b50-cpp-exception)
************ C++ exception test ***********
Exceptions enabled
Exception catched
******************************************
The nucleo-f767zi does the following (with both gnu and llvm toolchain):
main(): This is RIOT! (Version: 2022.04-devel-20-g95b50-cpp-exception)
************ C++ exception test ***********
Exceptions enabled
#! exit 1: powering off
With the default compiler flags there is no -fno-exceotions.
When adding -fno-exceotions manually and therefore disabling exceptions the test wouldn't even compile:
tests/cpp_exception/main.cpp:26:6: error: '__EXCEPTIONS' was not declared in this scope
26 | if(__EXCEPTIONS) {
| ^~~~~~~~~~~~
tests/cpp_exception/main.cpp:38:43: error: exception handling disabled, use '-fexceptions' to enable
38 | throw std::runtime_error("Exception");
| ^
tests/cpp_exception/main.cpp:41:30: error: 'e' was not declared in this scope
41 | printf("%s catched\n", e.what());
| ^
Exact the same behavior can be verified on esp32-wroom-32:
************ C++ exception test ***********
Exceptions enabled
#! exit 1: powering off
The devices are powered off instead of catching the exception.
Arduino has defined behabior, when trying to compile code that uses exceptions an error occurs error: exception handling disabled, use -fexceptions to enable.
I didn't try the other platforms because of missing hardware.
I don't want to discuss whether exceptions are useful for embedded development or not. But the behavior should be consistent. Either they should work or they should be disabled. When they do not work, they should not be used in any module imho.
Versions
It doesn't matter whether I build locally:
Operating System Environment
----------------------------
Operating System: macOS 11.6.2
Kernel: Darwin 20.6.0 x86_64 i386
./dist/tools/ci/print_toolchain_versions.sh: line 78: realpath: command not found
System shell: (probably dash)
make's shell: GNU bash, version 3.2.57(1)-release (x86_64-apple-darwin20)
Installed compiler toolchains
-----------------------------
native gcc: gcc (Homebrew GCC 10.2.0_4) 10.2.0
arm-none-eabi-gcc: arm-none-eabi-gcc (GNU Arm Embedded Toolchain 9-2020-q2-update) 9.3.1 20200408 (release)
avr-gcc: avr-gcc (Homebrew AVR GCC 9.3.0_3) 9.3.0
mips-mti-elf-gcc: missing
msp430-elf-gcc: missing
riscv-none-elf-gcc: missing
riscv64-unknown-elf-gcc: missing
riscv-none-embed-gcc: missing
xtensa-esp32-elf-gcc: xtensa-esp32-elf-gcc (crosstool-NG crosstool-ng-1.22.0-61-gab8375a) 5.2.0
xtensa-esp8266-elf-gcc: missing
clang: Apple clang version 13.0.0 (clang-1300.0.29.30)
Installed compiler libs
-----------------------
arm-none-eabi-newlib: "3.3.0"
mips-mti-elf-newlib: missing
msp430-elf-newlib: missing
riscv-none-elf-newlib: missing
riscv64-unknown-elf-newlib: missing
riscv-none-embed-newlib: missing
xtensa-esp32-elf-newlib: "2.2.0"
xtensa-esp8266-elf-newlib: missing
avr-libc: "2.0.0" ("20150208")
Installed development tools
---------------------------
ccache: missing
cmake: cmake version 3.21.0
cppcheck: missing
doxygen: 1.9.1
git: git version 2.32.0 (Apple Git-132)
make: GNU Make 4.3
openocd: Open On-Chip Debugger 0.10.0+dev-01514-ga8edbd020-dirty (2020-11-30-10:23)
python: Python 2.7.16
python2: Python 2.7.16
python3: Python 3.9.7
flake8: error: /usr/local/opt/python@3.9/bin/python3.9: No module named flake8
coccinelle: missing
or with the latest riot/riotbuild.