[cfe-dev] [clang-tidy] Excluding individual files/lines from clang-tidy checks

[Nikita via cfe-dev]

I think I'll explain why I need this functionality and why I think it
would be useful for others.

Currently clang-tidy doesn't provide a practical way to suppress
diagnostics from headers you don't have control over. If using a
function defined in such header causes a false positive, there is no
easy way to deal with this issue. Since you cannot modify a header,
you cannot add NOLINT to it. And adding NOLINT to each invocation of
such function is either impossible or hugely impractical if
invocations are ubiquitous.

Using the '-header-filter' doesn't help to address this issue as well.
Unless your own headers are strategically named, it is virtually
impossible to craft a regex that will filter out only the third-party
ones.

The '-line-filter' can be used to suppress such warnings, but it's not
very convenient. Instead of excluding a line that produces a warning
you have to include all other lines. Plus, it provides no way to
suppress only certain warnings from a file.

With all this mentioned, I think that clang-tidy would benefit from a
mechanism that is specifically designed to suppress certain warnings
from certain lines in a convenient way.

I don't see how existing options can be changed to provide this
functionality, so I propose adding a new option -
'--exclude-from-checks' - that will take a list of locations to
suppress warnings from. It can additionally take a list of checks to
suppress. The format of its' argument can be a JSON array similar to
the one '-line-filter' takes:
[{"name":"header.h","lines":[[1,5]],"checks":"cert-*"}].

I would gladly appreciate any feedback on this idea and look forward
to the discussion.

Regards,
Nikita

On Sat, Oct 29, 2016 at 12:11 AM, Nikita <nikita.kakuev at gmail.com> wrote:
> Well, I'm trying to mimic the behavior of '-line-filter'. But I also
> think that JSON is cumbersome. It requires putting arguments in
> quotes, plus the format itself seems a bit redundant. Specifying
> '[{"name":"file.h"}]' without the line range seemingly does nothing.
> Diagnostics for "file.h" will be emitted even without this filter.
>
> On Fri, Oct 28, 2016 at 11:52 PM, Richard via cfe-dev
> <cfe-dev at lists.llvm.org> wrote:
>>
>> [Please reply *only* to the list and do not include my email directly
>> in the To: or Cc: of your reply; otherwise I will not see your reply.
>> Thanks.]
>>
>> In article <CAGJfN2yb=3D-oCyTycsULN7F=Gn=KxFW_O4r4ndzCd8bFZ2muw at mail.gmail.com>,
>>     Nikita via cfe-dev <cfe-dev at lists.llvm.org> writes:
>>
>>> > clang-tidy '-exclude-from-checks=[{"name":"exclude.c","lines":[[5,7]]}]'
>>
>> Why are we specifying command-line arguments as JSON?
>>
>> It seems unnecessarily cumbersome to me.
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