Example test case that fails with undefined reference to getentropy:
Testing g++.robertl/eb77.C, -std=c++20
doing compile
Executing on host: /build/gcc-13-2709-g9ac9fde961f/bin/arm-none-eabi-g++ /build/src/gcc/gcc/testsuite/g++.old-deja/g++.robertl/eb77.C -mthumb -march=armv6s-m -mcpu=cortex-m0 -mfloat-abi=soft -fdiagnostics-plain-output -fmessage-length=0 -std=c++20 -pedantic-errors -Wno-long-long -Wl,--start-group -lc -lm -Wl,--end-group --specs=nosys.specs -Wl,--allow-multiple-definition -Wl,-u,_isatty,-u,_fstat -Wl,-wrap,exit -Wl,-wrap,_exit -Wl,-wrap,main -Wl,-wrap,abort -Wl,g++_tg.o -lm -o ./eb77.exe (timeout = 800)
spawn -ignore SIGHUP /build/gcc-13-2709-g9ac9fde961f/bin/arm-none-eabi-g++ /build/src/gcc/gcc/testsuite/g++.old-deja/g++.robertl/eb77.C -mthumb -march=armv6s-m -mcpu=cortex-m0 -mfloat-abi=soft -fdiagnostics-plain-output -fmessage-length=0 -std=c++20 -pedantic-errors -Wno-long-long -Wl,--start-group -lc -lm -Wl,--end-group --specs=nosys.specs -Wl,--allow-multiple-definition -Wl,-u,_isatty,-u,_fstat -Wl,-wrap,exit -Wl,-wrap,_exit -Wl,-wrap,main -Wl,-wrap,abort -Wl,g++_tg.o -lm -o ./eb77.exe
pid is 28414 -28414
/build/gcc-13-2709-g9ac9fde961f/bin/../lib/gcc/arm-none-eabi/13.0.0/../../../../arm-none-eabi/bin/ld: /build/gcc-13-2709-g9ac9fde961f/bin/../lib/gcc/arm-none-eabi/13.0.0/../../../../arm-none-eabi/lib/thumb/v6-m/nofp/libstdc++.a(random.o): in function `std::(anonymous namespace)::__libc_getentropy(void*)':
(.text._ZNSt12_GLOBAL__N_117__libc_getentropyEPv+0x8): undefined reference to `getentropy'
/build/gcc-13-2709-g9ac9fde961f/bin/../lib/gcc/arm-none-eabi/13.0.0/../../../../arm-none-eabi/bin/ld: /build/gcc-13-2709-g9ac9fde961f/bin/../lib/gcc/arm-none-eabi/13.0.0/../../../../arm-none-eabi/lib/thumb/v6-m/nofp/libstdc++.a(random.o): in function `std::random_device::_M_init(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)':
(.text._ZNSt13random_device7_M_initERKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEE+0x58): undefined reference to `getentropy'
/build/gcc-13-2709-g9ac9fde961f/bin/../lib/gcc/arm-none-eabi/13.0.0/../../../../arm-none-eabi/bin/ld: /build/gcc-13-2709-g9ac9fde961f/bin/../lib/gcc/arm-none-eabi/13.0.0/../../../../arm-none-eabi/lib/thumb/v6-m/nofp/libc.a(libc_a-arc4random.o): in function `_rs_stir':
(.text._rs_stir+0x8): undefined reference to `getentropy'
collect2: error: ld returned 1 exit status
pid is -1
close result is 28414 exp6 0 1
output is /build/gcc-13-2709-g9ac9fde961f/bin/../lib/gcc/arm-none-eabi/13.0.0/../../../../arm-none-eabi/bin/ld: /build/gcc-13-2709-g9ac9fde961f/bin/../lib/gcc/arm-none-eabi/13.0.0/../../../../arm-none-eabi/lib/thumb/v6-m/nofp/libstdc++.a(random.o): in function `std::(anonymous namespace)::__libc_getentropy(void*)':
(.text._ZNSt12_GLOBAL__N_117__libc_getentropyEPv+0x8): undefined reference to `getentropy'
/build/gcc-13-2709-g9ac9fde961f/bin/../lib/gcc/arm-none-eabi/13.0.0/../../../../arm-none-eabi/bin/ld: /build/gcc-13-2709-g9ac9fde961f/bin/../lib/gcc/arm-none-eabi/13.0.0/../../../../arm-none-eabi/lib/thumb/v6-m/nofp/libstdc++.a(random.o): in function `std::random_device::_M_init(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)':
(.text._ZNSt13random_device7_M_initERKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEE+0x58): undefined reference to `getentropy'
/build/gcc-13-2709-g9ac9fde961f/bin/../lib/gcc/arm-none-eabi/13.0.0/../../../../arm-none-eabi/bin/ld: /build/gcc-13-2709-g9ac9fde961f/bin/../lib/gcc/arm-none-eabi/13.0.0/../../../../arm-none-eabi/lib/thumb/v6-m/nofp/libc.a(libc_a-arc4random.o): in function `_rs_stir':
(.text._rs_stir+0x8): undefined reference to `getentropy'
collect2: error: ld returned 1 exit status
status 1
compiler exited with status 1
FAIL: g++.old-deja/g++.robertl/eb77.C -std=c++20 (test for excess errors)
Excess errors:
(.text._ZNSt12_GLOBAL__N_117__libc_getentropyEPv+0x8): undefined reference to `getentropy'
(.text._ZNSt13random_device7_M_initERKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEE+0x58): undefined reference to `getentropy'
(.text._rs_stir+0x8): undefined reference to `getentropy'
UNRESOLVED: g++.old-deja/g++.robertl/eb77.C -std=c++20 compilation failed to produce executable
Contributed by STMicroelectronics
Signed-off-by: Torbjörn SVENSSON <torbjorn.svensson@foss.st.com>
Torbjörn SVENSSON