Re: [PATCH 1/4] environ-selftests: Ignore -Wself-move warning

[Simon Marchi <simon.marchi@polymtl.ca>]

On 2017-06-21 23:28, Pedro Alves wrote:
> On 06/21/2017 10:05 PM, Simon Marchi wrote:
> 
>> Yeah, I didn't expect to have to put the #ifdefs for __clang__ though.
>> Without them, gcc emits a warning [-Wunknown-pragma].  We always have
>> the option to turn -Wunknown-pragma off globally, what do you prefer?
>> 
> 
> Don't both GCC and Clang understand "#pragma GCC diagnostic" instead?

Yes, but then it's GCC that complains that it doesn't know the warning:

/home/emaisin/src/binutils-gdb/gdb/unittests/environ-selftests.c:141:32: 
error: unknown option after ‘#pragma GCC diagnostic’ kind 
[-Werror=pragmas]
  #pragma GCC diagnostic ignored "-Wself-move"
                                 ^

> Or better even, wrap it in some macros (and use _Pragma):
> 
>  #define DIAGNOSTIC_PUSH _Pragma ("GCC diagnostic push")
>  #define DIAGNOSTIC_POP _Pragma ("GCC diagnostic pop")
>  #define DIAGNOSTIC_IGNORE(option) \
>    _Pragma (STRINGIFY (GCC diagnostic ignored option))

Oh that's interesting.  The gcc doc said that _Pragma was added exactly 
for this purpose (to be usable in macros).  I'll try that.

> Alternatively, you could replace the std::move with a cast
> to rvalue ref, which is just what std::move really is:
> 
>  -env = std::move (env);
>  +env = static_cast<gdb_environ &&> (env);

I guess that with a comment explaining why we use that it would be ok, 
but that would not be my first choice either.

Thanks,

Simon