build: enable control over the C++ interop modules

Treat the C++ interop modules similar to the Concurrency and
StringProcessing modules, enabled through a top-level global flag.  The
flag now enables disabling the C++ interop modules when the standard
library is built.

Based on the original work by Egor Zhdan!

Author: compnerd

CMakeLists.txt

@@ -605,6 +605,10 @@ option(SWIFT_ENABLE_EXPERIMENTAL_CONCURRENCY
   "Enable build of the Swift concurrency module"
   FALSE)
 
+option(SWIFT_ENABLE_EXPERIMENTAL_CXX_INTEROP
+  "Enable experimental C++ interop modules"
+  FALSE)
+
 option(SWIFT_ENABLE_EXPERIMENTAL_DISTRIBUTED
   "Enable experimental distributed actors and functions"
   FALSE)

stdlib/public/CMakeLists.txt

@@ -65,7 +65,9 @@ endif()
 
 add_subdirectory(SwiftShims/swift/shims)
 add_subdirectory(CommandLineSupport)
-add_subdirectory(Cxx)
+if(SWIFT_ENABLE_EXPERIMENTAL_CXX_INTEROP)
+  add_subdirectory(Cxx)
+endif()
 add_subdirectory(Threading)
 
 # This static library is shared across swiftCore and swiftRemoteInspection

utils/build-windows-toolchain.bat

@@ -212,6 +212,7 @@ cmake ^
   -D LLVM_VERSION_SUFFIX="" ^
 
   -D SWIFT_ENABLE_EXPERIMENTAL_CONCURRENCY=YES ^
+  -D SWIFT_ENABLE_EXPERIMENTAL_CXX_INTEROP=YES ^
   -D SWIFT_ENABLE_EXPERIMENTAL_DISTRIBUTED=YES ^
   -D SWIFT_ENABLE_EXPERIMENTAL_DIFFERENTIABLE_PROGRAMMING=YES ^
   -D SWIFT_ENABLE_EXPERIMENTAL_STRING_PROCESSING=YES ^
@@ -254,6 +255,7 @@ cmake ^
   -D SWIFT_PATH_TO_STRING_PROCESSING_SOURCE=%SourceRoot%\swift-experimental-string-processing ^
 
   -D SWIFT_ENABLE_EXPERIMENTAL_CONCURRENCY=YES ^
+  -D SWIFT_ENABLE_EXPERIMENTAL_CXX_INTEROP=YES ^
   -D SWIFT_ENABLE_EXPERIMENTAL_DISTRIBUTED=YES ^
   -D SWIFT_ENABLE_EXPERIMENTAL_DIFFERENTIABLE_PROGRAMMING=YES ^
   -D SWIFT_ENABLE_EXPERIMENTAL_STRING_PROCESSING=YES ^

utils/build-windows.bat

@@ -262,6 +262,7 @@ cmake^
     -DSWIFT_BUILD_SOURCEKIT:BOOL=YES^
     -DSWIFT_ENABLE_SOURCEKIT_TESTS:BOOL=YES^
     -DSWIFT_ENABLE_EXPERIMENTAL_CONCURRENCY=YES^
+    -DSWIFT_ENABLE_EXPERIMENTAL_CXX_INTEROP=YES^
     -DSWIFT_ENABLE_EXPERIMENTAL_DISTRIBUTED=YES^
     -DSWIFT_ENABLE_EXPERIMENTAL_DIFFERENTIABLE_PROGRAMMING=YES^
     -DSWIFT_ENABLE_EXPERIMENTAL_STRING_PROCESSING=YES^