[cfe-commits] [Patch] Add new warning for logical not on LHS of comparison

[Sean Silva]

How many lines of code have you compiled with this warning enabled?
How many bugs did it catch?
How many false positives did it have?

-- Sean Silva

On Fri, Oct 12, 2012 at 12:38 PM, Richard Trieu <rtrieu at google.com> wrote:
> This patch is for a new warning to Clang, called -Wlogical-not-compare.  It
> is designed to catch the case where the user is attempting to negate a
> comparison, but only manages to negate the LHS because of missing parens.
> For instance, warn here:
>
>      if (!x < 5)
>
> The user probably meant:
>
>      if (!(x < 5))
>
> or
>
>      if (x >= 5)
>
> When emitted, the warning will have a note suggesting this as a fix-it (drop
> the not and inverting the comparison operator).
>
> Also, a second note will be offer parenthesis around the LHS to silence this
> warning.
>
>      if ((!x) < 5)
>
> This will not warn.
>
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