openposix/strncpy1-1: Fix compiler errors/warnings

pragma diagnostic can support push/pop and be allowed inside functions
by commit 0955be65 on gcc-4.6, and it can support -Wstringop-truncation
by commit d8aad78 on gcc-8.1.  We try to avoid some compiler errors or
warnings by just using pragma diagnostic for test on newer gcc(i.e. >= gcc-8.1)
because compiling and running test don't get any failure after removing
pragma diagnostic on older gcc.

For example:
1)compiling test gets the following error on gcc-4.4:
  ------------------------------------------------------
  error: #pragma GCC diagnostic not allowed inside functions
  ------------------------------------------------------
2)compiling test gets the following warning on gcc-4.8:
  -----------------------------------------------------
  warning: unknown option after ‘#pragma GCC diagnostic’ kind [-Wpragmas]
  ------------------------------------------------------

Signed-off-by: Xiao Yang <yangx.jy@cn.fujitsu.com>
---
 .../conformance/interfaces/strncpy/1-1.c           |   10 +++++++---
 testcases/open_posix_testsuite/include/posixtest.h |    2 ++
 2 files changed, 9 insertions(+), 3 deletions(-)

Hi!
> Signed-off-by: Xiao Yang <yangx.jy@cn.fujitsu.com>
> ---
>  .../conformance/interfaces/strncpy/1-1.c           |   10 +++++++---
>  testcases/open_posix_testsuite/include/posixtest.h |    2 ++
>  2 files changed, 9 insertions(+), 3 deletions(-)
> 
> diff --git a/testcases/open_posix_testsuite/conformance/interfaces/strncpy/1-1.c b/testcases/open_posix_testsuite/conformance/interfaces/strncpy/1-1.c
> index 396bd60..7006b5f 100644
> --- a/testcases/open_posix_testsuite/conformance/interfaces/strncpy/1-1.c
> +++ b/testcases/open_posix_testsuite/conformance/interfaces/strncpy/1-1.c
> @@ -61,10 +61,14 @@ int main(void)
>          sample_str_1 = random_string(i);
>          num_bytes = rand() % i;
>  
> -        #pragma GCC diagnostic push
> -        #pragma GCC diagnostic ignored "-Wstringop-truncation"
> +	#if GCC_VERSION >= 80100
> +	# pragma GCC diagnostic push
> +	# pragma GCC diagnostic ignored "-Wstringop-truncation"
> +	#endif
>          ret_str = strncpy(sample_str_2, sample_str_1, num_bytes);
> -        #pragma GCC diagnostic pop
> +	#if GCC_VERSION >= 80100
> +	# pragma GCC diagnostic pop
> +	#endif

That looks even more silly than the original. I do not think that it's
reasonable to mess up the code that bad only to surpress a single
warning.

So what abour removing the pragmas entirely?

On 2018/12/14 16:33, Cyril Hrubis wrote:
> Hi!
>> Signed-off-by: Xiao Yang<yangx.jy@cn.fujitsu.com>
>> ---
>>   .../conformance/interfaces/strncpy/1-1.c           |   10 +++++++---
>>   testcases/open_posix_testsuite/include/posixtest.h |    2 ++
>>   2 files changed, 9 insertions(+), 3 deletions(-)
>>
>> diff --git a/testcases/open_posix_testsuite/conformance/interfaces/strncpy/1-1.c b/testcases/open_posix_testsuite/conformance/interfaces/strncpy/1-1.c
>> index 396bd60..7006b5f 100644
>> --- a/testcases/open_posix_testsuite/conformance/interfaces/strncpy/1-1.c
>> +++ b/testcases/open_posix_testsuite/conformance/interfaces/strncpy/1-1.c
>> @@ -61,10 +61,14 @@ int main(void)
>>           sample_str_1 = random_string(i);
>>           num_bytes = rand() % i;
>>
>> -        #pragma GCC diagnostic push
>> -        #pragma GCC diagnostic ignored "-Wstringop-truncation"
>> +	#if GCC_VERSION>= 80100
>> +	# pragma GCC diagnostic push
>> +	# pragma GCC diagnostic ignored "-Wstringop-truncation"
>> +	#endif
>>           ret_str = strncpy(sample_str_2, sample_str_1, num_bytes);
>> -        #pragma GCC diagnostic pop
>> +	#if GCC_VERSION>= 80100
>> +	# pragma GCC diagnostic pop
>> +	#endif
> That looks even more silly than the original. I do not think that it's
> reasonable to mess up the code that bad only to surpress a single
> warning.
>
> So what abour removing the pragmas entirely?
>
Hi Cyril,

I didn't get any failure after removing the pragmas on older/newer gcc, 
so i think

we can remove it directly.


Best Regards,
Xiao Yang