Swift: Support module libraries with command-line build systems

Wire up the flags needed to support module libraries built and used with
Swift. We need to pass `-bundle` to the linker when linking module
libraries on Darwin, and we need to pass `-export-dynamic` to the linker
when emitting an executable that exports symbols on Linux. This patch
wires up `CMAKE_SHARED_MODULE_CREATE_Swift_FLAGS` and
`CMAKE_SHARED_MODULE_LOADER_Swift_FLAG` on Darwin, and hooks up
`CMAKE_EXE_EXPORTS_Swift_FLAG` on Linux in order to support passing
things correctly.

We can't expose `CMAKE_EXE_LINKER_FLAGS` to Swift, as it contains flags
that the Swift compiler doesn't recognize, but the other
language-specific variables are safe to expose.

1 files changed, 1 insertions, 10 deletions

diff --git a/Tests/SwiftOnly/CMakeLists.txt b/Tests/SwiftOnly/CMakeLists.txt
index 3d2fe73..4754711 100644
--- a/Tests/SwiftOnly/CMakeLists.txt
+++ b/Tests/SwiftOnly/CMakeLists.txt
@@ -54,16 +54,7 @@ endif()
 add_library(SwiftIface INTERFACE)
 target_link_libraries(SwiftOnly PRIVATE SwiftIface)
 
-# @_alwaysEmitIntoClient ensures that the function body is inserted into the
-# swiftmodule instead of as a symbol in the binary itself. I'm doing this to
-# avoid having to link the executable. There are some flags required in order to
-# link an executable into a library that I didn't see CMake emitting for Swift
-# on macOS. AEIC is the easiest workaround that still tests this functionality.
-# Unfortunately, AEIC was only added recently (~Swift 5.2), so we need to check
-# that it is available before using it.
-if(CMAKE_Swift_COMPILER_VERSION VERSION_GREATER_EQUAL 5.2)
-  add_subdirectory("SwiftPlugin")
-endif()
+add_subdirectory("SwiftPlugin")
 
 function(test_cmp0157_default mode)
   if(POLICY CMP0157)