coding-system-require-warning

coding-system-require-warning is a variable defined in `C source code'.
Its value is

nil

Documentation:
Internal use only.
If non-nil, on writing a file, `select-safe-coding-system-function' is
called even if `coding-system-for-write' is non-nil. The command
`universal-coding-system-argument' binds this variable to t temporarily.