| Index: runtime/bin/file_system_watcher.h
 | 
| diff --git a/runtime/bin/file_system_watcher.h b/runtime/bin/file_system_watcher.h
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| index 7e142d873e327bacaf6523ec2e6e23e91d99e5bf..5026da71e38ef044ca188c7b1a3b90a8edf5d928 100644
 | 
| --- a/runtime/bin/file_system_watcher.h
 | 
| +++ b/runtime/bin/file_system_watcher.h
 | 
| @@ -5,6 +5,10 @@
 | 
|  #ifndef BIN_FILE_SYSTEM_WATCHER_H_
 | 
|  #define BIN_FILE_SYSTEM_WATCHER_H_
 | 
|  
 | 
| +#if defined(DART_IO_DISABLED)
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| +#error "file_system_watcher.h can only be included on builds with IO enabled"
 | 
| +#endif
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| +
 | 
|  #include <stdio.h>
 | 
|  #include <stdlib.h>
 | 
|  #include <string.h>
 | 
| 
 |