libswiftDemangle.so on Linux - swift

Question

While compiling Swift on Mac machine, there is a dynamic library libswiftDemangle.dylib created. I need the dynamic library created on Linux machine as well, however, the dynamic library isn't created after a compilation of a source code.
The file CMakeLists.txt at lib/SwiftDemangle/CMakeLists.txt contains:
add_swift_library(swiftDemangle SHARED
SwiftDemangle.cpp
MangleHack.cpp
LINK_LIBRARIES swiftBasic)
directive, however the library isn't created.
I use this command ./swift/utils/build-script -R -c --build-subdir build --install-prefix /mnt/servers/swift/install -j4 to build the project, eventually it runs cmake and ninja to build the project.
Any ideas?

Answer 1

I can take a shot at explaining why the library is not getting built on Linux, even if it's late probably.
The main subdirectory containing the library you mention is:
https://github.com/apple/swift/tree/master/lib
To build the libs in that directory, which are organized in subdirectories, the following CMakeLists.txt is used:
https://github.com/apple/swift/blob/master/lib/CMakeLists.txt.
As can be clearly seen in this file, the library that you mention is only built if the system is OSX/Darwin and not in the Linux case. The relevant code in the aforementioned CMakeLists.txt is:
add_subdirectory(RemoteAST)
add_subdirectory(Sema)
add_subdirectory(Serialization)
if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
add_subdirectory(SwiftDemangle)
endif()
add_subdirectory(SIL)
add_subdirectory(SILGen)
As you can see it,
if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
add_subdirectory(SwiftDemangle)
endif()
prevents SwiftDemangle to be built on Linux.
A superficial double check can be to look at:
https://github.com/apple/swift/blob/master/lib/SwiftDemangle/CMakeLists.txt
which will install or simlynk only *.dylib files.
It it worth mentioning that the swift-demangle tool (different from what you asked)
https://github.com/apple/swift/tree/master/tools/swift-demangle
is built on Linux.