Pass sanitizer flags to swift on Unix-y systems

This patch fixes the part of the build system where we aren't passing
the sanitizer flags to swift, so the linker isn't linking against the
sanitizer libraries.

Author: etcwilde

cmake/modules/AddSwift.cmake

@@ -75,6 +75,41 @@ function(_set_target_prefix_and_suffix target kind sdk)
   endif()
 endfunction()
 
+function(_add_host_variant_swift_sanitizer_flags target)
+  if (LLVM_USE_SANITIZER)
+    if (LLVM_ON_UNIX)
+
+      if (LLVM_USE_SANITIZER STREQUAL "Address")
+        set(_Swift_SANITIZER_FLAGS "-sanitize=address")
+      elseif (LLVM_USE_SANITIZER STREQUAL "HWAddress")
+        # Not supported?
+      elseif (LLVM_USE_SANITIZER MATCHES "Memory(WithOrigins)?")
+        # Not supported
+        if(LLVM_USE_SANITIZER STREQUAL "MemoryWithOrigins")
+          # Not supported
+        endif()
+      elseif (LLVM_USE_SANITIZER STREQUAL "Undefined")
+        set(_Swift_SANITIZER_FLAGS "-sanitize=undefined")
+      elseif (LLVM_USE_SANITIZER STREQUAL "Thread")
+        set(_Swift_SANITIZER_FLAGS "-sanitize=thread")
+      elseif (LLVM_USE_SANITIZER STREQUAL "DataFlow")
+        # Not supported
+      elseif (LLVM_USE_SANITIZER STREQUAL "Address;Undefined" OR
+              LLVM_USE_SANITIZER STREQUAL "Undefined;Address")
+        set(_Swift_SANITIZER_FLAGS "-sanitize=address -sanitize=undefined")
+      elseif (LLVM_USE_SANITIZER STREQUAL "Leaks")
+        # Not supported
+      else()
+        message(FATAL_ERROR "Unsupported value of LLVM_USE_SANITIZER: ${LLVM_USE_SANITIZER}")
+      endif()
+
+      target_compile_options(${name} PRIVATE $<$<COMPILE_LANGUAGE:Swift>:${_Swift_SANITIZER_FLAGS}>)
+    else ()
+      # TODO (etcwilde): Pass sanitizer flags to swiftc on windows
+    endif ()
+  endif ()
+endfunction()
+
 # Usage:
 # _add_host_variant_c_compile_link_flags(name)
 function(_add_host_variant_c_compile_link_flags name)
@@ -100,6 +135,8 @@ function(_add_host_variant_c_compile_link_flags name)
       MACCATALYST_BUILD_FLAVOR ""
       DEPLOYMENT_VERSION "${DEPLOYMENT_VERSION}")
     target_compile_options(${name} PRIVATE $<$<COMPILE_LANGUAGE:Swift>:-target;${target}>)
+
+   _add_host_variant_swift_sanitizer_flags(${name})
   endif()
 
   set(_sysroot