Re: [PATCH 4/4] Add -Wmisleading-indentation to -Wall

[Jeff Law <law at redhat dot com>]

On 10/29/2015 10:49 AM, David Malcolm wrote:
> Our documentation describes -Wall as enabling "all the warnings about
> constructions that some users consider questionable, and that are easy to avoid
> (or modify to prevent the warning), even in conjunction with macros."
>
> I believe that -Wmisleading-indentation meets these criteria, and is
> likely to be of benefit to users who may not read release notes; it
> warns for indentation that's misleading, but not for indentation
> that's merely bad: the former are places where a user will likely
> want to fix the code.
>
> The fix is usually easy and obvious: fix the misleadingly-indented
> code.  If that isn't an option for some reason, pragmas can be used to
> turn off the warning for a particular fragment of code:
>
>    #pragma GCC diagnostic push
>    #pragma GCC diagnostic ignored "-Wmisleading-indentation"
>      if (flag)
>        x = 3;
>        y = 2;
>    #pragma GCC diagnostic pop
>
> -Wmisleading-indentation has been tested with a variety of indentation
> styles (see gcc/testsuite/c-c++-common/Wmisleading-indentation.c)
> and on a variety of real-world projects.  For example, in:
>    https://www.mail-archive.com/gcc-patches@gcc.gnu.org/msg119790.html
> Patrick reports:
> "Tested by building the linux, git, vim, sqlite and gdb-binutils sources
>   with -Wmisleading-indentation."
>
> With the tweak earlier in this kit I believe we now have a good
> enough signal:noise ratio for this warning to be widely used; hence this
> patch adds the warning to -Wall.
>
> Bootstrapped&regrtested with x86_64-pc-linux-gnu.
>
> OK for trunk?
>
> gcc/c-family/ChangeLog:
> 	* c.opt (Wmisleading-indentation): Add to -Wall for C and C++.
>
> gcc/ChangeLog:
> 	* doc/invoke.texi (-Wall): Add -Wmisleading-indentation to the
> 	list.
> 	(-Wmisleading-indentation): Update documentation to reflect
> 	being enabled by -Wall in C/C++.
I'm sure we'll get some grief for this :-)

Approved once we're clean in GCC.  I'm going to explicitly say that 
we'll have to watch for fallout, particularly as we start getting 
feedback from Debian & Fedora mass-rebuilds as we approach release time. 
 If the fallout is too bad, we'll have to reconsider.

I'll pre-approve patches which fix anything caught by this option in GCC 
as long as the fix just adjusts whitespace :-)

jeff