Detect compiler.cppstd from CMAKE_CXX_STANDARD

[guy-david]

Conan dependencies do not share the same CMAKE_CXX_STANDARD set by a user in a parent project.

[CLAassistant]

All committers have signed the CLA.

[guy-david]

ping.

[czoido]

Hi @guy-david,
Sorry for not answering before and thanks for the contribution.
I think this could be also addressed without changes setting the compiler.cppstd in the call to conan_cmake_install like:

conan_cmake_configure(REQUIRES fmt/6.1.2 
                      GENERATORS cmake_find_package)

conan_cmake_autodetect(settings)
conan_cmake_install(PATH_OR_REFERENCE .
                    BUILD missing
                    REMOTE conancenter
                    SETTINGS ${settings}
                    SETTINGS compiler.cppstd=${CMAKE_CXX_STANDARD})

[guy-david]

That's true, however this change is not a feature.
The current default behaviour can build dependencies with the wrong C++ standard level, which are not all ABI compatible, leading to a segmentation fault.

[czoido]

That's true, however this change is not a feature. The current default behaviour can build dependencies with the wrong C++ standard level, which are not all ABI compatible, leading to a segmentation fault.

@guy-david Yes, this totally makes sense, I'll add a test and approve once the ci passes. Thanks for the contribution