Re: [OB PATCH] Avoid testcase build failures with -Wunused-value

[Pedro Alves <palves@redhat.com>]

On 6/23/20 12:45 PM, Gary Benson wrote:
> Pedro Alves wrote:
>> On 6/23/20 12:26 PM, Gary Benson via Gdb-patches wrote:
>>> --- a/gdb/testsuite/gdb.cp/namespace.cc
>>> +++ b/gdb/testsuite/gdb.cp/namespace.cc
>>> @@ -150,22 +150,22 @@ namespace C
>>>        // plan to have GDB try to print out, just to make sure that the
>>>        // compiler and I agree which ones should be legal!  It's easy
>>>        // to screw up when testing the boundaries of namespace stuff.
>>> -      c;
>>> +      int unused1 = c;
>>
>> It looks like such a fix will only work until the compiler decides
>> to enable -Wunused-variable by default too:
>>
>> testsuite/gdb.cp/namespace.cc:153:11: warning: unused variable 'unused' [-Wunused-variable]
>>       int unused = c;
>>           ^
>>
>> Try compiling the testcase with -Wall, with both g++ and clang++:
>>
>>  $ clang++ testsuite/gdb.cp/namespace.cc -Wall
>>
>> I think we should fix this with the more usual cast-to-void way:
>>
>>  (void) c;
> 
> Ok, but, out of interest, what stops the compiler ignoring that?

I don't know.  That's a pattern people have been using ages,
it may be special cased.

Thanks,
Pedro Alves