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Re: [patch] Add a new warning flag -Wself-assign
On 9 June 2010 20:32, Andrew Pinski <pinskia@gmail.com> wrote:
> On Wed, Jun 9, 2010 at 11:25 AM, Le-Chun Wu <lcwu@google.com> wrote:
>> It should be pretty easy to modify this patch to not warn about
>> self-initialization of local variables with this flag. However, what I
>> don't understand is why a user would want to work around (or suppress)
>> an uninitialized warning by doing self-initialization. They could have
>> just initialized a local variable to some other more meaningful value.
>> Initializing a variable with itself doesn't seem like a good way to
>> fix an uninitialized warning.
>
> Well this is the documented way of disabling the warning. ? If we want
> to change this, we should get rid of -Winit-self at the same time.
> And remove the documentation for this special case. ?I don't remember
> the full history behind my change of the documentation to mention this
> special case but from what I remember the source at one point did not
> warn about "int t = t +1;". ?And that I was fixing that case with
> keeping the special case of "int i = i;".
That is broken in C++ anyway http://gcc.gnu.org/PR34772, so who cares?
Let's get rid of this special case for Wuninitialized, get rid of
-Winit-self and let -Wself-assign warn for everything.
I would recommend that you add [C/C++] to the subject and/or CC
relevant maintainers.
The idea of the patch seems ok to me but the implementation seems
expensive. Adding yet another bit to one of the most used parts of the
whole compiler and the whole folding wrap-up are a bit scary. But I am
sure maintainers can give a more concrete answer and suggest
alternative implementations.
One thing:
+ warning_at (location, OPT_Wself_assign, G_("%qE is assigned to itself"),
+ lhs);
You do not need G_() here.
+Wself-assign
+Common Var(warn_self_assign) Init(0) Warning
+Warn when a variable is assigned to itself
This is not common but only C/C++, it should go in c.opt
Cheers,
Manuel.