msvc : silence codecvt c++17 deprecation warnings

[iboB]

• I have read the contributing guidelines
• Self-reported review complexity: Very Low

codecvt_utf8 is deprecated in C++17 (and removed in C++26). This silences the warnings when compiling with MSVC

[ggerganov]

I thought that setting the standard to C++11 would make the compiler ignore such warnings:

llama.cpp/common/CMakeLists.txt

Line 87 in a7abb78

target_compile_features (${TARGET} PUBLIC cxx_std_11)

Is it not the case?

[iboB]

I thought that setting the standard to C++11 would make the compiler ignore such warnings:

llama.cpp/common/CMakeLists.txt

Line 87 in a7abb78

target_compile_features (${TARGET} PUBLIC cxx_std_11)

Is it not the case?

Yes, but for there may be builds which set the standard to 17 or higher from above (for ABI compatibility for example)

PS pr for C++20 compatibility incoming 😄

[ggerganov]

You only need the change in common.cpp. For src/unicode.cpp there are no ABI compatibility concerns because it does not have public C++ interface as it is part of the llama library

[slaren]

How are you changing the C++ standard of the common library? Is that possible without changing its CMakeLists.txt file?

[iboB]

How are you changing the C++ standard of the common library? Is that possible without changing its CMakeLists.txt file?

If you set CMAKE_CXX_STANDARD it overrides target-specific ones for the sake of ABI compatibility

[iboB]

How are you changing the C++ standard of the common library? Is that possible without changing its CMakeLists.txt file?

If you set CMAKE_CXX_STANDARD it overrides target-specific ones for the sake of ABI compatibility

That is when you use cxx_std_11

[iboB]

You only need the change in common.cpp. For src/unicode.cpp there are no ABI compatibility concerns because it does not have public C++ interface as it is part of the llama library

Setting the standard from above affects all libs. Plus if you use static linking, it doesn't matter whether you export symbols explicity to risk ODR violations because of abi compatibility