I have a standard lib mismatch: "undefined symbol: public: class std::Cr::basic_string"

[Điền Đô]

Hi guys.

I got a common linking error.

It seems, i was linking a library that was compiled against a different version of c++ than the one i was using with the executable.

(I am using clang, c++17 and c++20 compilers. I use Qt creator and VS2022)

In my search results(library I am using), I know that "libc++ llvm-clang" is the default library for builds.

It is represented as " std::__1::  " ( __1  is the inline namespace that libc++ uses)

###

In the Pic, I am getting the error:

undefined symbol: public: class std::Cr::basic_string<char, struct std::Cr::char_traits<char>,

class std::Cr::allocator<char>> & __cdecl std::Cr::basic_string<char, struct std::Cr::char_traits<char>,

class std::Cr::allocator<char>>::append(char const *, unsigned __int64),......

###

std::Cr::  is the inline namespace the library is using.

Does anyone know about  std::Cr::  ?

There are no specific results for my case.

Any suggestions for me?

Thank you:))

[Điền Đô]

Any help, I sincerely appreciate it 😁 😁 😁

Vào lúc 22:38:27 UTC+7 ngày Thứ Ba, 3 tháng 10, 2023, Điền Đô đã viết:

[V I]

it's Google's custom libc++ (Cr stands for Chrome I believe). You either need to force it to use the regular libc++  when building libwebrtc (use_custom_libcxx=false), which is probably broken in some way, or link your app with that custom libc++

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[Điền Đô]

Hi:))

i followed your suggestion, i rebuilt webrtc with command: 

gn gen out/libc++ --args="is_debug=true use_custom_libcxx=false

and I got some warnings about using is_pod, as you saw in the picture. And I had build failure.

I also get the suggestion as shown in the Pic,  define _SILENCE_CXX20_IS_POD_DEPRECATION_WARNING or _SILENCE_ALL_CXX20_DEPRECATION_WARNINGS to suppress this warning.

I did so but without success :((

I rebuilt with the options the error message suggests, the command is as follows:

gn gen out/libc++ --args="is_debug=true use_custom_libcxx=false _SILENCE_CXX20_IS_POD_DEPRECATION_WARNING=true"

gn gen out/libc++ --args="is_debug=true use_custom_libcxx=false _SILENCE_ALL_CXX20_DEPRECATION_WARNINGS=true"

What is the correct command for this case?

Thanks for watching:))

Vào lúc 09:06:36 UTC+7 ngày Thứ Tư, 4 tháng 10, 2023, V I đã viết:

[tudor....@gmail.com]

I'm having the same issue when trying to link an app against libwebrtc.a

> or link your app with that custom libc++

Where can I find the custom libc++?

[Khun V]

It doesn't really exist as a library (I mean .a/.lib file). You need to add all the object files from ${WEBRTC_ROOT}/out/obj/buildtools/third_party/libc++/libc++ and ${WEBRTC_ROOT}/out/obj/buildtools/third_party/libc++abi/libc++abi to the build

To view this discussion on the web visit https://groups.google.com/d/msgid/discuss-webrtc/1f6efc30-0ee9-4d98-9453-51442b1089ffn%40googlegroups.com.

[tudor....@gmail.com]

@Khun V Thank you, that helped!

Now when I'm building my own app, I have lots of errors like this one

undefined reference to `rtc::Thread::SetName(std::basic_string_view<char, std::char_traits<char> >, void const*)'

Which I guess is related to the fact that the compiler does not generate the signature needed for the call to the appropriate method:

rtc::Thread::SetName(std::__Cr::basic_string_view<char, std::__Cr::char_traits<char> >, void const*)

So clearly not using the std::__Cr::basic_string_view.

I guess my (#include <string> etc.) includes should point to the custom libstdc++ includes. But how do I do this?