-gnatuPrint a list of units required by this compilation on stdout.
The listing includes all units on which the unit being compiled depends
either directly or indirectly.
-pass-exit-codesIf this switch is not used, the exit code returned by gcc when
compiling multiple files indicates whether all source files have
been successfully used to generate object files or not.
When -pass-exit-codes is used, gcc exits with an extended
exit status and allows an integrated development environment to better
react to a compilation failure. Those exit status are:
| `5' | There was an error in at least one source file. |
| `3' | At least one source file did not generate an object file. |
| `2' | The compiler died unexpectedly (internal error for example). |
| `0' | An object file has been generated for every source file. |