Merge pull request #33966 from compnerd/extension

build: repair cross-compilation for Windows after #33908

Author: compnerd

stdlib/cmake/modules/SwiftSource.cmake

@@ -610,12 +610,12 @@ function(_compile_swift_files
   endif()
 
   set(line_directive_tool "${SWIFT_SOURCE_DIR}/utils/line-directive")
-  # line-directive needs full path on Windows.
-  if (CMAKE_SYSTEM_NAME STREQUAL Windows)
-    set(swift_compiler_tool "${SWIFT_NATIVE_SWIFT_TOOLS_PATH}/swiftc.exe")
-  else()
-    set(swift_compiler_tool "${SWIFT_NATIVE_SWIFT_TOOLS_PATH}/swiftc")
+
+  if(CMAKE_HOST_SYSTEM_NAME STREQUAL Windows)
+    set(HOST_EXECUTABLE_SUFFIX .exe)
   endif()
+  set(swift_compiler_tool "${SWIFT_NATIVE_SWIFT_TOOLS_PATH}/swiftc${HOST_EXECUTABLE_SUFFIX}")
+
   set(swift_compiler_tool_dep)
   if(SWIFT_INCLUDE_TOOLS)
     # Depend on the binary itself, in addition to the symlink.