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Re: RFC: -Wall by default


On 04/05/2012 12:30 PM, Vincent Lefevre wrote:
> On 2012-04-05 11:55:45 +0100, Andrew Haley wrote:
>> On 04/05/2012 11:50 AM, Vincent Lefevre wrote:
>>> On 2012-04-04 20:01:27 +0100, Andrew Haley wrote:
>>>> On 04/04/2012 07:11 PM, Gabriel Dos Reis wrote:
>>>>> Really?  Such as what?
>>>>
>>>> Such as "I wrote a perfectly legal C program, and gcc spewed out
>>>> a ton of messages."
>>>
>>> What's a "legal C program"?
>>
>> It's generally used to mean one that is fully defined by the
>> specifications in effect, often some combination of POSIX and ISO C,
>> with perhaps some vendor extensions.  Why do you ask?
> 
> Because: What if the specifications in effect say (as some vendor
> extension) that some construct will generate some warning?

Interesting.  I had not considered that, but I have never seen such a
specification.  Usually warnings are for things that are permitted by
a specification, but not "good" in some way.  That's why warnings are
usually optional, AFAIK; the program is well-defined, but has some
properties that are, in the opinion of the compiler writer,
undesirable.

> Note that warnings in general are not forbidden by ISO C, so that
> there is nothing wrong as far as ISO C is concerned.

No, but ISO C only talks about diagnostics anyway: there is no real
distinction between warnings and errors.

Andrew.


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