std::string causes JVM to crash and C++ 20 support

[cmesa121]

I have a project using the c++20. ( i was using the compiler="cpp20" builds fine)

I had some issues because of chrono specific methods so i tried to skip them but that didn't work.

What worked was pulling the javacpp repo and building the project with this added to the properties file:

platform.compiler.cpp20=/std:c++20 /Zc:__cplusplus

and then skip the problematic constructor and now it builds.

The issue that i have now is that i can't seem to expose a simple StringToString function.

The project builds but whenever i try to call the function from the java side i get:

EXCEPTION_ACCESS_VIOLATION

Test.h

EXPORT std::string StringToString(const std::string& input);

Test.cpp

std::string StringToString(const std::string& input)
{
return input;
}

I've tested the above with the flag set to cpp20 and cpp17 but no luck.

Generated code:

public static native @stdstring BytePointer StringToString(@stdstring BytePointer input);
public static native @stdstring String StringToString(@stdstring String input);

Do you have any idea how to get over the java issue where JVM crashes when trying to use strings?
Also for the other problem can we release a version of javacpp that works with c++20?

If you need any other details I'm happy to share more about the project.

Thanks,
Catalin

[saudet]

Yes, please open a pull request for starters

[saudet]

As for the issue with your StringToString, that case is available in unit tests and works fine on all platforms:
https://github.com/bytedeco/javacpp/blob/master/src/test/resources/org/bytedeco/javacpp/AdapterTest.h#L8
So I'm guessing there's something else somewhere that isn't working that isn't related to std::string.

[cmesa121]

Let me revisit these and come back to you.
std::string might be related to the way I'm building the package locally