Re: [boost] Bug report rejected as conformant

Subject: Re: [boost] Bug report rejected as conformant
From: Edward Diener (eldiener_at_[hidden])
Date: 2018-01-13 20:14:55

On 1/13/2018 1:55 PM, Marc Glisse via Boost wrote:
> On Sat, 13 Jan 2018, Edward Diener via Boost wrote:
> 
>> I recently reported a preprocessor bug in Oracle C++ 12.6 on their 
>> online forum when compiling a C program example. I even cited the C11 
>> standard in showing that Oracle C++ 12.6's actions were 
>> non-conformant. The answer I was given, from an Oracle C++ developer 
>> who said he was a member of the C++ standard committee, is that since 
>> Oracle C++ 12.6 gives a warning message rather than a compiler error 
>> the compiler was compliant with the C standard, since the standard 
>> only requires a diagnostic message to be considered standard compliant 
>> when it does not implement the compiler according to the standard, and 
>> that a warning was a diagnostic message. Furthermore since there was a 
>> way to force the particular warning to be considered an error, Oracle 
>> was not going to change their compiler. At that point I "lost it" so 
>> to speak.
>>
>> I cannot conceive that any C/C++ standard would specify that giving a 
>> warning rather than an error, when not complying with the C/C++ 
>> standard, would then make the compiler compliant. Comments ?
> 
> Uh, that's what all compilers do all the time when they implement 
> extensions to the standard. With gcc, you even need to specify 
> -Wpedantic to get those required diagnostics. I am really surprised that 
> this is the first compiler for which you notice this...

So a compiler is allowed to implement an extension to the standard which 
is non-compliant with the standard, and then claim compliance to the 
standard by outputting a warning message instead ? In that case what 
hope is there for the programmer to write C/C++ standard compliant code 
using such a compiler, since the compiler is "inventing" a standard 
which does not exist ?

Note that the error I reported was not when using any 
-std=some_compilers_extension mode ( as in gcc's -std=gnu++nn mode as 
opposed to -std=c++nn mode) but with -std=c11 mode, which is explained 
as being an implementation of the c11 standard. In other words if I were 
using an Oracle c11 mode, as in a hypothetical -std=oracle++c11, I would 
not have complained about their extension to the standard or their 
cavalier treatment of a bug as not being a bug because they produced a 
warning. But that was not the case and the mode being used was the 
-std=c11 mode, which evidently means to Oracle C++ whatever they feel 
like defining as the c11 standard even if it does not follow the actual 
c11 standard.