Is it ok to mix rtti on/off c++ shared libraries

[skysky97]

I have an executable app compiled with -frtti, and a shared library libnative.so compiled with -fno-rtti.

STL: c++_shared
ndk: r21
The executable and library are built via ndk CMake.

In app code, throw std::runtime_error and try catch std::exception, it always failed.

Example:

app.cpp

#include <exception>
#include <stdexcept>
#include <iostream>
#include <unistd.h>

int main() {
 try {
   throw std::runtime_error("User defined runtime error in app");
 }
 catch (const std::exception& e) {
 std::cout << "catch exception: " << e.what() << std::endl;
 }
 // catch (const std::runtime_error& e) {
 // std::cout << "catch runtime error: " << e.what() << std::endl;
 // }
 catch (...) {
 std::cout << "catch unknow exception" << std::endl;
 }
while(1) {
 sleep(5);
 }
}

libnative.cpp

#include <stdexcept>
void dummy() {
 throw std::logic_error("User defined logic error in libnative");
}

[DanAlbert]

In app code, throw std::runtime_error and try catch std::exception, it always failed.

Define failed? I tried your code and everything is working as I expect. The std::exception catch handler catches the exception. Afaict the presence of libnative is also irrelevant. Here's my CMakeLists.txt:

cmake_minimum_required(VERSION 3.23.1)
project(rtti-test CXX)

add_library(native SHARED native.cpp)
target_compile_options(native PRIVATE -fno-rtti)

add_executable(app app.cpp)
target_compile_options(app PRIVATE -frtti)
target_link_libraries(app PRIVATE native)

Built with

$ cmake -DCMAKE_TOOLCHAIN_FILE=~/Library/Android/sdk/ndk/24.0.8215888/build/cmake/android.toolchain.cmake -DANDROID_STL=c++_shared -DANDROID_ABI=arm64-v8a ..
$ make

adb pushed the outputs (and libc++_shared.so) to /data/local/tmp and ran with

adb shell "LD_LIBRARY_PATH=/data/local/tmp /data/local/tmp/app"
catch exception: User defined runtime error in app

[skysky97]

Failed means it always run into the catch(...) block.

Yes, setting LD_LIBRARY_PATH for libc++_shared.so works fine. I'm sorry that I forgot to mention it.

But in my case, libc++_shared.so is located at /system/lib64/vndk-sp-28/, and app is located at /vendor/bin/, libnative.so is located at /vendor/lib64/. So libc++_shared.so is loaded into the vendor section default linker namespace (link to vndk namespace) by linker. That makes test result different.

And when I throw logic_error exception and try catch, it runs into the catch (std::exception) block correctly. The difference is that logic_error appears in the libnative too.

[DanAlbert]

If it's a VNDK specific issue we're not going to be able to help. The only thing the NDK and VNDK have in common is the name. Best to follow b.android.com and file a bug with the appropriate section of the platform (or better yet, talk to your TAM).