#[ffi_export]

Attributes

• Non-"C" ABIs

  Currently #[ffi_export] defaults to a #[no_mangle] pub extern "C" function definition, i.e., it exports a function using the default C ABI of the platform it is compiled against (target platform).

  Sometimes a special ABI is required, in which case specifying the ABI is desirable.

  Imagined syntax: an optional ABI = "<abi>" attribute parameter:

  #[ffi_export(ABI = "system")]
  fn ...
  

• Custom export_name.

  To override the name (the symbol) the item is exported with (by virtue of the default #[no_mangle], the item is exported with a symbol equal to the identifier used for its name), one could imagine someone wanting to develop their own namespacing tool / name mangling convention when controling both ends of the FFI, so they may want to provide an export_name override too.

  Imagined syntax: an optional export_name = ... attribute parameter.

• unsafe-ly disabling the runtime sanity checks.

  As mentioned in the sanity checks section, it is intended that all #[ffi_export]-ed functions perform some sanity checks on the raw inputs they receive, before transmuting those to the actual ReprC types. Still, for some functions where performance is critical and the caller of the #[ffi_export]-ed function is trusted not give invalid values, it will be possible to opt-out of such check when debug_assertions are disabled by marking each function where one wants to disable the checks with an unsafe parameter, such as:

  #[ffi_export]
  #[safer_ffi(unsafe { skip_sanity_checks() })]
  fn ...
  

  or on specific params:

  #[ffi_export]
  fn set_log_level (
      #[safer_ffi(unsafe { skip_sanity_checks() })]
      level: LogLevel,
      ...
  ) -> ...