thejohnfreeman
How should `[INTERFACE_]{C,CXX}_STANDARD` and `[INTERFACE_]{C,CXX}_EXTENSIONS` affect `cflags` and `cxxflags`?
Does CMake compute the mapping and fill in [INTERFACE_]COMPILE_OPTIONS for us, or do we have to re-implement that functionality?
Conan should probably not pull it up into the flags (if anything at all). The idea is that it's hard to reason about a global flag string if all subprojects fight for the right to control it. And with the user too! It complicates the process of forming and checking the valid flag string for the whole DAG. Projects should instead operate on the input flag string and explicitly fail if there are incompatibilities.
@Minimonium does Conan have a way to model "minimum C++ standard" in cpp_info or elsewhere? Will it (i.e. is there an open issue)?
It can check for 'compiler.cppstd' (or something along the lines) in the recipe' configure function. The standard is part of the ABI so it's modelled in the settings. Recipes should raise an error if that value is incompatible. I think the autorecipes project can generate something along the lines, but parsing all the ways the standard can br defined in cmake is a bit messy.