[m-rev.] for post-commit review: shut up some C# warnings

[Julien Fischer]

On Fri, 11 Mar 2022, Peter Wang wrote:

> On Fri, 11 Mar 2022 10:20:29 +1100 "Zoltan Somogyi" <zoltan.somogyi at runbox.com> wrote:

>> diff --git a/library/io.file.m b/library/io.file.m
>> index a722fcc44..7f70d1ef3 100644
>> --- a/library/io.file.m
>> +++ b/library/io.file.m
>> @@ -1603,6 +1603,7 @@ get_temp_directory(Dir, !IO) :-
>>      [will_not_call_mercury, promise_pure, tabled_for_io, thread_safe,
>>          may_not_duplicate],
>>  "
>> +#pragma warning disable 162, 168, 169, 219, 1717
>>      try {
>>          Dir = System.IO.Path.GetTempPath();
>>          OK = (Dir != null) ? 1 : 0;
>> @@ -1610,6 +1611,7 @@ get_temp_directory(Dir, !IO) :-
>>          Dir = null;
>>          OK = 0;
>>      }
>> +#pragma warning restore
>>  ").
>
> I pushed a more direct fix for the unused variable warning (168).
> If it breaks some older C# compiler that we supposedly support then it
> can be reverted easily.

The oldest C# compiler we need to support is the Mono CS compiler
version 6.8.0.X (i.e. the one on RHEL 7 based systems), since that's
the one installed on the server that builds the ROTDs.

Julien.