[stdlib] Add an option SWIFT_STDLIB_ENABLE_STRICT_CONCURRENCY_COMPLETE to enable building the stdlib with strict-concurrency=complete.

It is currently by default off.

Author: gottesmm

CMakeLists.txt

@@ -655,6 +655,10 @@ option(SWIFT_ENABLE_EXPERIMENTAL_OBSERVATION
   "Enable build of the Swift observation module"
   FALSE)
 
+option(SWIFT_STDLIB_ENABLE_STRICT_CONCURRENCY_COMPLETE
+  "Build the stdlib with -strict-concurrency=complete"
+  FALSE)
+
 option(SWIFT_ENABLE_SYNCHRONIZATION
   "Enable build of the Swift Synchronization module"
   FALSE)

stdlib/cmake/modules/SwiftSource.cmake

@@ -613,6 +613,10 @@ function(_compile_swift_files
     list(APPEND swift_flags "-Xfrontend" "-disable-round-trip-debug-types") # NOTE: temporary until we fix mangling!
   endif()
 
+  if (SWIFT_STDLIB_ENABLE_STRICT_CONCURRENCY_COMPLETE)
+    list(APPEND swift_flags "-strict-concurrency=complete")
+  endif()
+
   if (SWIFT_STDLIB_USE_RELATIVE_PROTOCOL_WITNESS_TABLES)
     list(APPEND swift_flags "-Xfrontend" "-enable-relative-protocol-witness-tables")
     list(APPEND swift_flags "-Xfrontend" "-swift-async-frame-pointer=never")