This should work on Windows

After talking with compnerd, because we're passing this directly to the
swift driver, we shouldn't have to do anything weird with the flags and
it should "just work". I'm frustrated enough with Windows that I'm just
going to go with that and go to bed. If I broke something, I'm sorry. I
tried as far as my sanity would allow.

Author: etcwilde

cmake/modules/AddSwift.cmake

@@ -77,36 +77,31 @@ 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")
+    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
-      else()
-        message(FATAL_ERROR "Unsupported value of LLVM_USE_SANITIZER: ${LLVM_USE_SANITIZER}")
       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>:${_Swift_SANITIZER_FLAGS}>)
-    else ()
-      # TODO (etcwilde): Pass sanitizer flags to swiftc on windows
-    endif ()
+    target_compile_options(${name} PRIVATE $<$<COMPILE_LANGUAGE:Swift>:${_Swift_SANITIZER_FLAGS}>)
   endif ()
 endfunction()