Please, take '-Wmisleading-indentation' out of -Wall

[Manuel López-Ibáñez]

On 04/05/16 19:20, David Malcolm wrote:
> On Wed, 2016-05-04@18:15 +0200, Antonio Diaz Diaz wrote:
>>     - It can't be portably disabled; older versions of gcc do not
>> accept
>>       '-Wno-misleading-indentation'. (At least 4.1.2 does not accept
>> it).
>
> FWIW "-Wall -Wno-misleading-indentation" works for me with gcc 4.8.3

It should work since GCC 4.4 (7 years old). See 
https://gcc.gnu.org/wiki/FAQ#wnowarning

>>     - -Wempty-body is much simpler to test for, and in general less
>>       questionable than -Wmisleading-indentation, yet it is not
>> enabled by
>>       -Wall.
>>

Many useful warnings are outside -Wall/-Wextra because there were bugs when 
initially implemented, users complained, they were moved out and then either 
the bugs were forgotten or they got fixed but nobody bothered to move them 
again within -Wall/-Wextra. See https://gcc.gnu.org/PR52961

Nowadays it is extremely easy to disable a warning that annoys you (the name is 
written in the message and you can use #pragmas very selectively), but still 
quite hard to discover which warning you need to enable that could have found a 
certain bug. It is also much harder to find regressions in warnings not enabled 
by -Wall -Wextra because they are not tested as much.

I really commend David for being brave and putting the warning in -Wall. The 
easy way out would have been to say: "I know how to enable it, so let's hide it 
so that users do not complain to me about bugs that I don't suffer". We (myself 
included) have done this plenty of times in the past and the result is always 
the same: bugs don't get fixed, regressions appear, and users complain about 
missing warnings that are actually already implemented.

>> I think that keeping separated categories of warnings (instead of
>> warning about everything by default) is a valuable feature. Maybe
>> both
>> -Wempty-body and -Wmisleading-indentation (and any future similar
>> options) could be put in a new category (-Wcoding-style or
>> -Wstatic-analysis, for example).

I agree that GCC warnings could be better categorized, but your proposed 
categories are not clearly defined. A better classification would look at the 
possibilities of false positives, how easy is to silence it, whether it is 
"undefined/unspecified at runtime", "undefined/unspecif under some conditions 
but not others", "atypical code that is often/sometimes a bug", "typical code 
that is often/sometimes a bug", etc. Of course, this would be a lot of work 
that no one wants to do ;-)

Cheers,

	Manuel.