This commit reworks the C++ standard library configurations such that:
* the separation between the Zephyr minimal C++ library and the fully
featured C++ standard libraries, such as GNU libstdc++, is clear.
This is done by deprecating the Kconfig `CONFIG_LIB_CPLUSPLUS`
symbol, which implies that the minimal C++ library is selected when
set to `n`, and introducing the `CONFIG_MINIMAL_LIBCPP` symbol.
* the type of the selected C++ standard library is clear. This is done
by introducing a Kconfig choice, `LIBCPP_IMPLEMENTATION`, for the C++
standard library type and providing the choice symbols for each
library type supported, such as `CONFIG_MINIMAL_LIBCPP` and
`CONFIG_GLIBCXX_LIBCPP`.
Signed-off-by: Stephanos Ioannidis <stephanos.ioannidis@nordicsemi.no>
This commit relocates the "C++ minimal library" components, that
implement a very limited subset of the standard C++ library, to a
dedicated directory, `lib/cpp/minimal`, in order to provide a clear
separation among the different C++ library components.
After this refactoring, the top `lib/cpp` directory should only contain
the sub-directories for each C++ library (i.e. `abi`, `minimal`). In
the future, a C++ library-specific shim layer implementation may be
added as sub-directories under `lib/cpp` as well (e.g. `libstdc++`
sub-directory containing the shim layer implementation for the GCC
libstdc++ library) -- this is similar to how the libc directories are
structured under `lib/libc`.
Signed-off-by: Stephanos Ioannidis <stephanos.ioannidis@nordicsemi.no>
This commit relocates the "C++ ABI library" components such as
global constructor/destructor and initialiser handlers to a dedicated
directory, `lib/cpp/abi`, in order to provide a clear separation
between the C++ ABI/runtime library and the standard C++ library
components.
Note that the Zephyr C++ ABI library currently implements the GNU/GCC
C++ ABI, which is the de-facto standard ABI used by many compilers
including Clang -- it may be necessary to sub-divide the `lib/cpp/abi`
into `lib/cpp/abi/gnu` and `lib/cpp/abi/someotherabi` in the future
when adding the support for a C++ compiler that expects an ABI vastly
different from the GNU C++ ABI.
Signed-off-by: Stephanos Ioannidis <stephanos.ioannidis@nordicsemi.no>
This commit moves the files under `subsys/cpp` directory to the
`lib/cpp` directory because the C++ ABI runtime library and the
standard C++ library components are not a "subsystem" (aka. API) in
conventional sense and is better described as a "library."
Classifying the C++ ABI runtime library and the standard C++ library as
"libraries" instead of "subsystems" also better aligns with how the
existing C standard library implementation (`lib/libc`) is handled.
Signed-off-by: Stephanos Ioannidis <stephanos.ioannidis@nordicsemi.no>
