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Re: [Consult] g++: About "-Wunused-variable" for constant variable initialized by function


On 10/13/14 21:18, Chen Gang wrote:
> On 10/13/14 18:53, Jason Merrill wrote:
>> On 10/12/2014 10:32 AM, Chen Gang wrote:
>>>    [root@localhost qemu_cc]# cat test.cc
>>>    const char n() { return 1; }
>>>    const char c =  n();
>>>    [root@localhost qemu_cc]# /usr/local/bin/g++ -Wall -O0 -c -o test.o test.cc
>>>    [root@localhost qemu_cc]# /usr/local/bin/g++ -Wall -O2 -c -o test.o test.cc
>>>    test.cc:2:12: warning: 'c' defined but not used [-Wunused-variable]
>>>     const char c =  n();
>>>                ^
>>
>> The warning is correct (and new).  Please submit bug reports via the website; see https://gcc.gnu.org/bugs/
>>

Thank Jason Merrill, again. At present, I have got enough confirmation
from you and other members (excuse me, I am not quite familiar with C++,
for me, it is a complex language, so need several members confirmation).

And if no additional reply within this week, I shall submit bug reports,
and try to fix it within this month (although I am really not quite
sure).

I am not quite familiar with C++, so if any members worry about me: feel
that I am not quite suitable to report bug and fix it, please let me
know within this week.

Thanks.

> 
> OK, thanks. After finish this consult, I shall report bugs, and shall
> try to fix it (I got it from Qemu which in my current focus border).
> Hope I can finish within this month.
> 
> And one another consult: if the constant variable is defined in header
> file, and never be used, need our g++ still report warning about
> [-Wunused-variable] too (for me, I guess, not)?
> 
> 
> Thanks.
> 

-- 
Chen Gang

Open, share, and attitude like air, water, and life which God blessed


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