Unable to build packages using Clang with libc++ on Linux.

[conan-io]

Unable to build packages using Clang with libc++ on Linux.

[l90lpa]

Hello, I've just noticed the new SETTINGS option for conan_cmake_run(). Is it recommended to use this to set the particular compiler.libc++ setting? I'm asking because this will populate the _SETTINGS variable with two instances setting compiler.libcxx e.g. "-s compiler.libcxx=libstdc++ ... -s compiler.libcxx=libc++". Is it the intended behaviour of conan install to use the last value specified?

[memsharded]

Hi @l90lpa

Not, it is not intended to use the last value, I think cmake-conan should avoids its repetition, this might need fixing. Thanks for reporting it!

[memsharded]

I am having a look. What would be the "standard" CMake approach for defining the usage of libc++ in Linux-Clang? The idea of conan_cmake_settings is that it automatically extracts the settings from the current CMake configuration, so it would be great to know if such configuration exists for libc++.

[Artalus]

At first I was rather surprised that the wrapper doesn't look into Conan profile for compiler.libcxx value. Then I thought that the main problem with this approach would be - what if user wants to use some other profile than default?

Clearly specifying libcxx or profile name somewhere in CMakeLists.txt would be a bad move for anything that is intended to build outside of strictly set environment. Maybe conan.cmake should take into account the values of some other CMake variables, like conan-package-tools do with envvars?

In this case, if I call CMake from terminal, I could go cmake -DCMAKE_CONAN_LIBCXX=libc++ .., and when using CMake in Qt Creator with my predefined Kit I could also specify additional variables in the Kit itself.