This is a sample that demonstrates to how use a custom libc++, to build a Swift module that depends on some C++ headers that use the custom libc++, and how to use such a Swift module throughout the rest of the Swift program which depends on system's C++ stdlib, like the MSVC C++ stdlib on Windows.
This sample is geared up for x64 windows, as it includes a distribution of libc++ for that platform, but it should work just as well on other platforms too.
> cmake -G Ninja -B build -S .
> ninja -C build
> build\bin\SampleMainSwiftProgram.exe
expected output:
hello existing in custom c++ stdlib world!
program version (from C++ vector -> [Int]): [1, 2, 3]
tab: tab 1
will go to: swift.org
test C++ system lib
This project is broken down into the following subtargets:
-
'CommonCore': A core Swift library with some common data types used by all targets, like the
Versionstruct. This library doesn't use C++ interoperability, and thus it can be used by other Swift libraries, that either use custom libc++, or system's C++ stdlib. -
'CoreLibCxx' : This is the C++ library that depends on using the custom libc++. It's header only for the purpose of simplifying this sample.
-
'CoreLib': This is the Swift library that uses custom libc++ and imports 'CoreLibCxx', to provide a Swift wrapper that operates on 'CoreLibCxx'. It uses two public class protocols 'Tab' and 'Program' to provide a resilient abstraction over the implementation of the 'Program' and 'Tab' functionality in this library. Such abstraction ensures that C++ dependency details from 'CoreLibCxx' do not leak to other Swift dependencies, like 'SampleMainSwiftProgram'. These two protocols are implemented using two private classes that operate on the APIs provided by the 'CoreLibCxx' C++ library.
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'SampleMainSwiftProgram': This is the Swift executable that acts as the rest of the program, and uses system's C++ stdlib. It interacts with 'CoreLib' using some Swift-only function and protocol-based APIs from 'CoreLib'.